Merge commit 'b71f3405606d49b9735606b479c3415a0ca9810f' into clippyup

src/tools/clippy/.gitignore

@@ -29,6 +29,7 @@ out
 
 # gh pages docs
 util/gh-pages/lints.json
+**/metadata_collection.json
 
 # rustfmt backups
 *.rs.bk

src/tools/clippy/CONTRIBUTING.md

@@ -118,7 +118,7 @@ which `IntelliJ Rust` will be able to understand.
 Run `cargo dev ide_setup --repo-path <repo-path>` where `<repo-path>` is a path to the rustc repo
 you just cloned.
 The command will add path-dependencies pointing towards rustc-crates inside the rustc repo to
-Clippys `Cargo.toml`s and should allow rust-analyzer to understand most of the types that Clippy uses.
+Clippys `Cargo.toml`s and should allow `IntelliJ Rust` to understand most of the types that Clippy uses.
 Just make sure to remove the dependencies again before finally making a pull request!
 
 [rustc_repo]: https://github.com/rust-lang/rust/

src/tools/clippy/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "clippy"
-version = "0.1.53"
+version = "0.1.54"
 authors = ["The Rust Clippy Developers"]
 description = "A bunch of helpful lints to avoid common pitfalls in Rust"
 repository = "https://github.com/rust-lang/rust-clippy"
@@ -52,6 +52,7 @@ rustc_tools_util = { version = "0.2.0", path = "rustc_tools_util" }
 deny-warnings = []
 integration = ["tempfile"]
 internal-lints = ["clippy_lints/internal-lints"]
+metadata-collector-lint = ["internal-lints", "clippy_lints/metadata-collector-lint"]
 
 [package.metadata.rust-analyzer]
 # This package uses #[feature(rustc_private)]

src/tools/clippy/clippy_lints/Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "clippy_lints"
 # begin automatic update
-version = "0.1.53"
+version = "0.1.54"
 # end automatic update
 authors = ["The Rust Clippy Developers"]
 description = "A bunch of helpful lints to avoid common pitfalls in Rust"
@@ -20,6 +20,7 @@ pulldown-cmark = { version = "0.8", default-features = false }
 quine-mc_cluskey = "0.2.2"
 regex-syntax = "0.6"
 serde = { version = "1.0", features = ["derive"] }
+serde_json = { version = "1.0", optional = true }
 toml = "0.5.3"
 unicode-normalization = "0.1"
 semver = "0.11"
@@ -32,6 +33,7 @@ url = { version = "2.1.0", features = ["serde"] }
 deny-warnings = []
 # build clippy with internal lints enabled, off by default
 internal-lints = ["clippy_utils/internal-lints"]
+metadata-collector-lint = ["serde_json", "clippy_utils/metadata-collector-lint"]
 
 [package.metadata.rust-analyzer]
 # This crate uses #[feature(rustc_private)]

src/tools/clippy/clippy_lints/src/comparison_chain.rs

@@ -1,6 +1,6 @@
 use clippy_utils::diagnostics::span_lint_and_help;
 use clippy_utils::ty::implements_trait;
-use clippy_utils::{get_trait_def_id, if_sequence, is_else_clause, paths, SpanlessEq};
+use clippy_utils::{get_trait_def_id, if_sequence, in_constant, is_else_clause, paths, SpanlessEq};
 use rustc_hir::{BinOpKind, Expr, ExprKind};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
@@ -64,6 +64,10 @@ impl<'tcx> LateLintPass<'tcx> for ComparisonChain {
             return;
         }
 
+        if in_constant(cx, expr.hir_id) {
+            return;
+        }
+
         // Check that there exists at least one explicit else condition
         let (conds, _) = if_sequence(expr);
         if conds.len() < 2 {

src/tools/clippy/clippy_lints/src/default.rs

@@ -1,6 +1,6 @@
 use clippy_utils::diagnostics::{span_lint_and_note, span_lint_and_sugg};
 use clippy_utils::source::snippet_with_macro_callsite;
-use clippy_utils::{any_parent_is_automatically_derived, contains_name, match_def_path, paths};
+use clippy_utils::{any_parent_is_automatically_derived, contains_name, in_macro, match_def_path, paths};
 use if_chain::if_chain;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_errors::Applicability;
@@ -75,6 +75,7 @@ impl_lint_pass!(Default => [DEFAULT_TRAIT_ACCESS, FIELD_REASSIGN_WITH_DEFAULT]);
 impl LateLintPass<'_> for Default {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
         if_chain! {
+            if !in_macro(expr.span);
             // Avoid cases already linted by `field_reassign_with_default`
             if !self.reassigned_linted.contains(&expr.span);
             if let ExprKind::Call(path, ..) = expr.kind;

src/tools/clippy/clippy_lints/src/eval_order_dependence.rs

@@ -1,5 +1,6 @@
 use clippy_utils::diagnostics::{span_lint, span_lint_and_note};
 use clippy_utils::{get_parent_expr, path_to_local, path_to_local_id};
+use if_chain::if_chain;
 use rustc_hir::intravisit::{walk_expr, NestedVisitorMap, Visitor};
 use rustc_hir::{BinOpKind, Block, Expr, ExprKind, Guard, HirId, Local, Node, Stmt, StmtKind};
 use rustc_lint::{LateContext, LateLintPass};
@@ -70,20 +71,19 @@ declare_lint_pass!(EvalOrderDependence => [EVAL_ORDER_DEPENDENCE, DIVERGING_SUB_
 impl<'tcx> LateLintPass<'tcx> for EvalOrderDependence {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
         // Find a write to a local variable.
-        match expr.kind {
+        let var = if_chain! {
-            ExprKind::Assign(lhs, ..) | ExprKind::AssignOp(_, lhs, _) => {
+            if let ExprKind::Assign(lhs, ..) | ExprKind::AssignOp(_, lhs, _) = expr.kind;
-                if let Some(var) = path_to_local(lhs) {
+            if let Some(var) = path_to_local(lhs);
-                    let mut visitor = ReadVisitor {
+            if expr.span.desugaring_kind().is_none();
-                        cx,
+            then { var } else { return; }
-                        var,
+        };
-                        write_expr: expr,
+        let mut visitor = ReadVisitor {
-                        last_expr: expr,
+            cx,
-                    };
+            var,
-                    check_for_unsequenced_reads(&mut visitor);
+            write_expr: expr,
-                }
+            last_expr: expr,
-            },
+        };
-            _ => {},
+        check_for_unsequenced_reads(&mut visitor);
-        }
     }
     fn check_stmt(&mut self, cx: &LateContext<'tcx>, stmt: &'tcx Stmt<'_>) {
         match stmt.kind {
@@ -305,7 +305,7 @@ impl<'a, 'tcx> Visitor<'tcx> for ReadVisitor<'a, 'tcx> {
                     self.cx,
                     EVAL_ORDER_DEPENDENCE,
                     expr.span,
-                    "unsequenced read of a variable",
+                    &format!("unsequenced read of `{}`", self.cx.tcx.hir().name(self.var)),
                     Some(self.write_expr.span),
                     "whether read occurs before this write depends on evaluation order",
                 );

src/tools/clippy/clippy_lints/src/implicit_return.rs

@@ -1,13 +1,16 @@
-use clippy_utils::diagnostics::span_lint_and_then;
+use clippy_utils::{
-use clippy_utils::match_panic_def_id;
+    diagnostics::span_lint_and_sugg,
-use clippy_utils::source::snippet_opt;
+    get_async_fn_body, is_async_fn,
-use if_chain::if_chain;
+    source::{snippet_with_applicability, snippet_with_context, walk_span_to_context},
+    visitors::visit_break_exprs,
+};
 use rustc_errors::Applicability;
 use rustc_hir::intravisit::FnKind;
-use rustc_hir::{Body, Expr, ExprKind, FnDecl, HirId, MatchSource, StmtKind};
+use rustc_hir::{Block, Body, Expr, ExprKind, FnDecl, FnRetTy, HirId};
-use rustc_lint::{LateContext, LateLintPass};
+use rustc_lint::{LateContext, LateLintPass, LintContext};
+use rustc_middle::lint::in_external_macro;
 use rustc_session::{declare_lint_pass, declare_tool_lint};
-use rustc_span::source_map::Span;
+use rustc_span::{Span, SyntaxContext};
 
 declare_clippy_lint! {
     /// **What it does:** Checks for missing return statements at the end of a block.
@@ -39,89 +42,160 @@ declare_clippy_lint! {
 
 declare_lint_pass!(ImplicitReturn => [IMPLICIT_RETURN]);
 
-static LINT_BREAK: &str = "change `break` to `return` as shown";
+fn lint_return(cx: &LateContext<'_>, span: Span) {
-static LINT_RETURN: &str = "add `return` as shown";
+    let mut app = Applicability::MachineApplicable;
-
+    let snip = snippet_with_applicability(cx, span, "..", &mut app);
-fn lint(cx: &LateContext<'_>, outer_span: Span, inner_span: Span, msg: &str) {
+    span_lint_and_sugg(
-    let outer_span = outer_span.source_callsite();
+        cx,
-    let inner_span = inner_span.source_callsite();
+        IMPLICIT_RETURN,
-
+        span,
-    span_lint_and_then(cx, IMPLICIT_RETURN, outer_span, "missing `return` statement", |diag| {
+        "missing `return` statement",
-        if let Some(snippet) = snippet_opt(cx, inner_span) {
+        "add `return` as shown",
-            diag.span_suggestion(
+        format!("return {}", snip),
-                outer_span,
+        app,
-                msg,
+    );
-                format!("return {}", snippet),
-                Applicability::MachineApplicable,
-            );
-        }
-    });
 }
 
-fn expr_match(cx: &LateContext<'_>, expr: &Expr<'_>) {
+fn lint_break(cx: &LateContext<'_>, break_span: Span, expr_span: Span) {
+    let mut app = Applicability::MachineApplicable;
+    let snip = snippet_with_context(cx, expr_span, break_span.ctxt(), "..", &mut app).0;
+    span_lint_and_sugg(
+        cx,
+        IMPLICIT_RETURN,
+        break_span,
+        "missing `return` statement",
+        "change `break` to `return` as shown",
+        format!("return {}", snip),
+        app,
+    )
+}
+
+#[derive(Clone, Copy, PartialEq, Eq)]
+enum LintLocation {
+    /// The lint was applied to a parent expression.
+    Parent,
+    /// The lint was applied to this expression, a child, or not applied.
+    Inner,
+}
+impl LintLocation {
+    fn still_parent(self, b: bool) -> Self {
+        if b { self } else { Self::Inner }
+    }
+
+    fn is_parent(self) -> bool {
+        self == Self::Parent
+    }
+}
+
+// Gets the call site if the span is in a child context. Otherwise returns `None`.
+fn get_call_site(span: Span, ctxt: SyntaxContext) -> Option<Span> {
+    (span.ctxt() != ctxt).then(|| walk_span_to_context(span, ctxt).unwrap_or(span))
+}
+
+fn lint_implicit_returns(
+    cx: &LateContext<'tcx>,
+    expr: &'tcx Expr<'_>,
+    // The context of the function body.
+    ctxt: SyntaxContext,
+    // Whether the expression is from a macro expansion.
+    call_site_span: Option<Span>,
+) -> LintLocation {
     match expr.kind {
-        // loops could be using `break` instead of `return`
+        ExprKind::Block(
-        ExprKind::Block(block, ..) | ExprKind::Loop(block, ..) => {
+            Block {
-            if let Some(expr) = &block.expr {
+                expr: Some(block_expr), ..
-                expr_match(cx, expr);
+            },
+            _,
+        ) => lint_implicit_returns(
+            cx,
+            block_expr,
+            ctxt,
+            call_site_span.or_else(|| get_call_site(block_expr.span, ctxt)),
+        )
+        .still_parent(call_site_span.is_some()),
+
+        ExprKind::If(_, then_expr, Some(else_expr)) => {
+            // Both `then_expr` or `else_expr` are required to be blocks in the same context as the `if`. Don't
+            // bother checking.
+            let res = lint_implicit_returns(cx, then_expr, ctxt, call_site_span).still_parent(call_site_span.is_some());
+            if res.is_parent() {
+                // The return was added as a parent of this if expression.
+                return res;
             }
-            // only needed in the case of `break` with `;` at the end
+            lint_implicit_returns(cx, else_expr, ctxt, call_site_span).still_parent(call_site_span.is_some())
-            else if let Some(stmt) = block.stmts.last() {
+        },
-                if_chain! {
+
-                    if let StmtKind::Semi(expr, ..) = &stmt.kind;
+        ExprKind::Match(_, arms, _) => {
-                    // make sure it's a break, otherwise we want to skip
+            for arm in arms {
-                    if let ExprKind::Break(.., Some(break_expr)) = &expr.kind;
+                let res = lint_implicit_returns(
-                    then {
+                    cx,
-                            lint(cx, expr.span, break_expr.span, LINT_BREAK);
+                    arm.body,
+                    ctxt,
+                    call_site_span.or_else(|| get_call_site(arm.body.span, ctxt)),
+                )
+                .still_parent(call_site_span.is_some());
+                if res.is_parent() {
+                    // The return was added as a parent of this match expression.
+                    return res;
+                }
+            }
+            LintLocation::Inner
+        },
+
+        ExprKind::Loop(block, ..) => {
+            let mut add_return = false;
+            visit_break_exprs(block, |break_expr, dest, sub_expr| {
+                if dest.target_id.ok() == Some(expr.hir_id) {
+                    if call_site_span.is_none() && break_expr.span.ctxt() == ctxt {
+                        lint_break(cx, break_expr.span, sub_expr.unwrap().span);
+                    } else {
+                        // the break expression is from a macro call, add a return to the loop
+                        add_return = true;
                     }
                 }
-            }
+            });
-        },
+            if add_return {
-        // use `return` instead of `break`
+                #[allow(clippy::option_if_let_else)]
-        ExprKind::Break(.., break_expr) => {
+                if let Some(span) = call_site_span {
-            if let Some(break_expr) = break_expr {
+                    lint_return(cx, span);
-                lint(cx, expr.span, break_expr.span, LINT_BREAK);
+                    LintLocation::Parent
-            }
+                } else {
-        },
+                    lint_return(cx, expr.span);
-        ExprKind::If(.., if_expr, else_expr) => {
+                    LintLocation::Inner
-            expr_match(cx, if_expr);
-
-            if let Some(else_expr) = else_expr {
-                expr_match(cx, else_expr);
-            }
-        },
-        ExprKind::Match(.., arms, source) => {
-            let check_all_arms = match source {
-                MatchSource::IfLetDesugar {
-                    contains_else_clause: has_else,
-                } => has_else,
-                _ => true,
-            };
-
-            if check_all_arms {
-                for arm in arms {
-                    expr_match(cx, arm.body);
                 }
             } else {
-                expr_match(cx, arms.first().expect("`if let` doesn't have a single arm").body);
+                LintLocation::Inner
             }
         },
-        // skip if it already has a return statement
+
-        ExprKind::Ret(..) => (),
+        // If expressions without an else clause, and blocks without a final expression can only be the final expression
-        // make sure it's not a call that panics
+        // if they are divergent, or return the unit type.
-        ExprKind::Call(expr, ..) => {
+        ExprKind::If(_, _, None) | ExprKind::Block(Block { expr: None, .. }, _) | ExprKind::Ret(_) => {
-            if_chain! {
+            LintLocation::Inner
-                if let ExprKind::Path(qpath) = &expr.kind;
+        },
-                if let Some(path_def_id) = cx.qpath_res(qpath, expr.hir_id).opt_def_id();
+
-                if match_panic_def_id(cx, path_def_id);
+        // Any divergent expression doesn't need a return statement.
-                then { }
+        ExprKind::MethodCall(..)
-                else {
+        | ExprKind::Call(..)
-                    lint(cx, expr.span, expr.span, LINT_RETURN)
+        | ExprKind::Binary(..)
-                }
+        | ExprKind::Unary(..)
+        | ExprKind::Index(..)
+            if cx.typeck_results().expr_ty(expr).is_never() =>
+        {
+            LintLocation::Inner
+        },
+
+        _ =>
+        {
+            #[allow(clippy::option_if_let_else)]
+            if let Some(span) = call_site_span {
+                lint_return(cx, span);
+                LintLocation::Parent
+            } else {
+                lint_return(cx, expr.span);
+                LintLocation::Inner
             }
         },
-        // everything else is missing `return`
-        _ => lint(cx, expr.span, expr.span, LINT_RETURN),
     }
 }
 
@@ -129,19 +203,32 @@ impl<'tcx> LateLintPass<'tcx> for ImplicitReturn {
     fn check_fn(
         &mut self,
         cx: &LateContext<'tcx>,
-        _: FnKind<'tcx>,
+        kind: FnKind<'tcx>,
-        _: &'tcx FnDecl<'_>,
+        decl: &'tcx FnDecl<'_>,
         body: &'tcx Body<'_>,
         span: Span,
         _: HirId,
     ) {
-        if span.from_expansion() {
+        if (!matches!(kind, FnKind::Closure) && matches!(decl.output, FnRetTy::DefaultReturn(_)))
+            || span.ctxt() != body.value.span.ctxt()
+            || in_external_macro(cx.sess(), span)
+        {
             return;
         }
-        let body = cx.tcx.hir().body(body.id());
+
-        if cx.typeck_results().expr_ty(&body.value).is_unit() {
+        let res_ty = cx.typeck_results().expr_ty(&body.value);
+        if res_ty.is_unit() || res_ty.is_never() {
             return;
         }
-        expr_match(cx, &body.value);
+
+        let expr = if is_async_fn(kind) {
+            match get_async_fn_body(cx.tcx, body) {
+                Some(e) => e,
+                None => return,
+            }
+        } else {
+            &body.value
+        };
+        lint_implicit_returns(cx, expr, expr.span.ctxt(), None);
     }
 }

src/tools/clippy/clippy_lints/src/lib.rs

@@ -383,6 +383,7 @@ mod zero_sized_map_values;
 // end lints modules, do not remove this comment, it’s used in `update_lints`
 
 pub use crate::utils::conf::Conf;
+use crate::utils::conf::TryConf;
 
 /// Register all pre expansion lints
 ///
@@ -400,56 +401,40 @@ pub fn register_pre_expansion_lints(store: &mut rustc_lint::LintStore) {
 }
 
 #[doc(hidden)]
-pub fn read_conf(args: &[rustc_ast::NestedMetaItem], sess: &Session) -> Conf {
+pub fn read_conf(sess: &Session) -> Conf {
     use std::path::Path;
-    match utils::conf::file_from_args(args) {
+    let file_name = match utils::conf::lookup_conf_file() {
-        Ok(file_name) => {
+        Ok(Some(path)) => path,
-            // if the user specified a file, it must exist, otherwise default to `clippy.toml` but
+        Ok(None) => return Conf::default(),
-            // do not require the file to exist
+        Err(error) => {
-            let file_name = match file_name {
+            sess.struct_err(&format!("error finding Clippy's configuration file: {}", error))
-                Some(file_name) => file_name,
-                None => match utils::conf::lookup_conf_file() {
-                    Ok(Some(path)) => path,
-                    Ok(None) => return Conf::default(),
-                    Err(error) => {
-                        sess.struct_err(&format!("error finding Clippy's configuration file: {}", error))
-                            .emit();
-                        return Conf::default();
-                    },
-                },
-            };
-
-            let file_name = if file_name.is_relative() {
-                sess.local_crate_source_file
-                    .as_deref()
-                    .and_then(Path::parent)
-                    .unwrap_or_else(|| Path::new(""))
-                    .join(file_name)
-            } else {
-                file_name
-            };
-
-            let (conf, errors) = utils::conf::read(&file_name);
-
-            // all conf errors are non-fatal, we just use the default conf in case of error
-            for error in errors {
-                sess.struct_err(&format!(
-                    "error reading Clippy's configuration file `{}`: {}",
-                    file_name.display(),
-                    error
-                ))
                 .emit();
-            }
+            return Conf::default();
+        },
+    };
 
-            conf
+    let file_name = if file_name.is_relative() {
-        },
+        sess.local_crate_source_file
-        Err((err, span)) => {
+            .as_deref()
-            sess.struct_span_err(span, err)
+            .and_then(Path::parent)
-                .span_note(span, "Clippy will use default configuration")
+            .unwrap_or_else(|| Path::new(""))
-                .emit();
+            .join(file_name)
-            Conf::default()
+    } else {
-        },
+        file_name
+    };
+
+    let TryConf { conf, errors } = utils::conf::read(&file_name);
+    // all conf errors are non-fatal, we just use the default conf in case of error
+    for error in errors {
+        sess.struct_err(&format!(
+            "error reading Clippy's configuration file `{}`: {}",
+            file_name.display(),
+            error
+        ))
+        .emit();
     }
+
+    conf
 }
 
 /// Register all lints and lint groups with the rustc plugin registry
@@ -1020,6 +1005,13 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         store.register_late_pass(|| box utils::internal_lints::MatchTypeOnDiagItem);
         store.register_late_pass(|| box utils::internal_lints::OuterExpnDataPass);
     }
+    #[cfg(feature = "metadata-collector-lint")]
+    {
+        if std::env::var("ENABLE_METADATA_COLLECTION").eq(&Ok("1".to_string())) {
+            store.register_late_pass(|| box utils::internal_lints::metadata_collector::MetadataCollector::default());
+        }
+    }
+
     store.register_late_pass(|| box utils::author::Author);
     store.register_late_pass(|| box await_holding_invalid::AwaitHolding);
     store.register_late_pass(|| box serde_api::SerdeApi);

src/tools/clippy/clippy_lints/src/loops/needless_collect.rs

@@ -7,9 +7,10 @@ use clippy_utils::{is_trait_method, path_to_local_id, paths};
 use if_chain::if_chain;
 use rustc_errors::Applicability;
 use rustc_hir::intravisit::{walk_block, walk_expr, NestedVisitorMap, Visitor};
-use rustc_hir::{Block, Expr, ExprKind, GenericArg, HirId, Local, Pat, PatKind, QPath, StmtKind};
+use rustc_hir::{Block, Expr, ExprKind, GenericArg, GenericArgs, HirId, Local, Pat, PatKind, QPath, StmtKind, Ty};
 use rustc_lint::LateContext;
 use rustc_middle::hir::map::Map;
+
 use rustc_span::symbol::{sym, Ident};
 use rustc_span::{MultiSpan, Span};
 
@@ -26,7 +27,7 @@ fn check_needless_collect_direct_usage<'tcx>(expr: &'tcx Expr<'_>, cx: &LateCont
         if chain_method.ident.name == sym!(collect) && is_trait_method(cx, &args[0], sym::Iterator);
         if let Some(generic_args) = chain_method.args;
         if let Some(GenericArg::Type(ref ty)) = generic_args.args.get(0);
-        let ty = cx.typeck_results().node_type(ty.hir_id);
+        if let Some(ty) = cx.typeck_results().node_type_opt(ty.hir_id);
         if is_type_diagnostic_item(cx, ty, sym::vec_type)
             || is_type_diagnostic_item(cx, ty, sym::vecdeque_type)
             || match_type(cx, ty, &paths::BTREEMAP)
@@ -58,20 +59,33 @@ fn check_needless_collect_direct_usage<'tcx>(expr: &'tcx Expr<'_>, cx: &LateCont
 }
 
 fn check_needless_collect_indirect_usage<'tcx>(expr: &'tcx Expr<'_>, cx: &LateContext<'tcx>) {
+    fn get_hir_id<'tcx>(ty: Option<&Ty<'tcx>>, method_args: Option<&GenericArgs<'tcx>>) -> Option<HirId> {
+        if let Some(ty) = ty {
+            return Some(ty.hir_id);
+        }
+
+        if let Some(generic_args) = method_args {
+            if let Some(GenericArg::Type(ref ty)) = generic_args.args.get(0) {
+                return Some(ty.hir_id);
+            }
+        }
+
+        None
+    }
     if let ExprKind::Block(block, _) = expr.kind {
         for stmt in block.stmts {
             if_chain! {
                 if let StmtKind::Local(
                     Local { pat: Pat { hir_id: pat_id, kind: PatKind::Binding(_, _, ident, .. ), .. },
-                    init: Some(init_expr), .. }
+                    init: Some(init_expr), ty, .. }
                 ) = stmt.kind;
                 if let ExprKind::MethodCall(method_name, collect_span, &[ref iter_source], ..) = init_expr.kind;
                 if method_name.ident.name == sym!(collect) && is_trait_method(cx, init_expr, sym::Iterator);
-                if let Some(generic_args) = method_name.args;
+                if let Some(hir_id) = get_hir_id(*ty, method_name.args);
-                if let Some(GenericArg::Type(ref ty)) = generic_args.args.get(0);
+                if let Some(ty) = cx.typeck_results().node_type_opt(hir_id);
-                if let ty = cx.typeck_results().node_type(ty.hir_id);
                 if is_type_diagnostic_item(cx, ty, sym::vec_type) ||
                     is_type_diagnostic_item(cx, ty, sym::vecdeque_type) ||
+                    is_type_diagnostic_item(cx, ty, sym::BinaryHeap) ||
                     match_type(cx, ty, &paths::LINKED_LIST);
                 if let Some(iter_calls) = detect_iter_and_into_iters(block, *ident);
                 if let [iter_call] = &*iter_calls;

src/tools/clippy/clippy_lints/src/loops/while_immutable_condition.rs

@@ -28,11 +28,14 @@ pub(super) fn check<'tcx>(cx: &LateContext<'tcx>, cond: &'tcx Expr<'_>, expr: &'
         return;
     }
     let used_in_condition = &var_visitor.ids;
-    let no_cond_variable_mutated = if let Some(used_mutably) = mutated_variables(expr, cx) {
+    let mutated_in_body = mutated_variables(expr, cx);
-        used_in_condition.is_disjoint(&used_mutably)
+    let mutated_in_condition = mutated_variables(cond, cx);
-    } else {
+    let no_cond_variable_mutated =
-        return;
+        if let (Some(used_mutably_body), Some(used_mutably_cond)) = (mutated_in_body, mutated_in_condition) {
-    };
+            used_in_condition.is_disjoint(&used_mutably_body) && used_in_condition.is_disjoint(&used_mutably_cond)
+        } else {
+            return;
+        };
     let mutable_static_in_cond = var_visitor.def_ids.iter().any(|(_, v)| *v);
 
     let mut has_break_or_return_visitor = HasBreakOrReturnVisitor {

src/tools/clippy/clippy_lints/src/matches.rs

@@ -1590,9 +1590,9 @@ fn is_none_arm(cx: &LateContext<'_>, arm: &Arm<'_>) -> bool {
 // Checks if arm has the form `Some(ref v) => Some(v)` (checks for `ref` and `ref mut`)
 fn is_ref_some_arm(cx: &LateContext<'_>, arm: &Arm<'_>) -> Option<BindingAnnotation> {
     if_chain! {
-        if let PatKind::TupleStruct(ref qpath, pats, _) = arm.pat.kind;
+        if let PatKind::TupleStruct(ref qpath, [first_pat, ..], _) = arm.pat.kind;
         if is_lang_ctor(cx, qpath, OptionSome);
-        if let PatKind::Binding(rb, .., ident, _) = pats[0].kind;
+        if let PatKind::Binding(rb, .., ident, _) = first_pat.kind;
         if rb == BindingAnnotation::Ref || rb == BindingAnnotation::RefMut;
         if let ExprKind::Call(e, args) = remove_blocks(arm.body).kind;
         if let ExprKind::Path(ref some_path) = e.kind;
@@ -1712,6 +1712,7 @@ mod redundant_pattern_match {
     use clippy_utils::{is_lang_ctor, is_qpath_def_path, is_trait_method, paths};
     use if_chain::if_chain;
     use rustc_ast::ast::LitKind;
+    use rustc_data_structures::fx::FxHashSet;
     use rustc_errors::Applicability;
     use rustc_hir::LangItem::{OptionNone, OptionSome, PollPending, PollReady, ResultErr, ResultOk};
     use rustc_hir::{
@@ -1739,6 +1740,13 @@ mod redundant_pattern_match {
     /// deallocate memory. For these types, and composites containing them, changing the drop order
     /// won't result in any observable side effects.
     fn type_needs_ordered_drop(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
+        type_needs_ordered_drop_inner(cx, ty, &mut FxHashSet::default())
+    }
+
+    fn type_needs_ordered_drop_inner(cx: &LateContext<'tcx>, ty: Ty<'tcx>, seen: &mut FxHashSet<Ty<'tcx>>) -> bool {
+        if !seen.insert(ty) {
+            return false;
+        }
         if !ty.needs_drop(cx.tcx, cx.param_env) {
             false
         } else if !cx
@@ -1750,12 +1758,12 @@ mod redundant_pattern_match {
             // This type doesn't implement drop, so no side effects here.
             // Check if any component type has any.
             match ty.kind() {
-                ty::Tuple(_) => ty.tuple_fields().any(|ty| type_needs_ordered_drop(cx, ty)),
+                ty::Tuple(_) => ty.tuple_fields().any(|ty| type_needs_ordered_drop_inner(cx, ty, seen)),
-                ty::Array(ty, _) => type_needs_ordered_drop(cx, ty),
+                ty::Array(ty, _) => type_needs_ordered_drop_inner(cx, ty, seen),
                 ty::Adt(adt, subs) => adt
                     .all_fields()
                     .map(|f| f.ty(cx.tcx, subs))
-                    .any(|ty| type_needs_ordered_drop(cx, ty)),
+                    .any(|ty| type_needs_ordered_drop_inner(cx, ty, seen)),
                 _ => true,
             }
         }
@@ -1772,7 +1780,7 @@ mod redundant_pattern_match {
         {
             // Check all of the generic arguments.
             if let ty::Adt(_, subs) = ty.kind() {
-                subs.types().any(|ty| type_needs_ordered_drop(cx, ty))
+                subs.types().any(|ty| type_needs_ordered_drop_inner(cx, ty, seen))
             } else {
                 true
             }

src/tools/clippy/clippy_lints/src/methods/mod.rs

@@ -2189,27 +2189,6 @@ const TRAIT_METHODS: [ShouldImplTraitCase; 30] = [
     ShouldImplTraitCase::new("std::ops::Sub", "sub",  2,  FN_HEADER,  SelfKind::Value,  OutType::Any, true),
 ];
 
-#[rustfmt::skip]
-const PATTERN_METHODS: [(&str, usize); 17] = [
-    ("contains", 1),
-    ("starts_with", 1),
-    ("ends_with", 1),
-    ("find", 1),
-    ("rfind", 1),
-    ("split", 1),
-    ("rsplit", 1),
-    ("split_terminator", 1),
-    ("rsplit_terminator", 1),
-    ("splitn", 2),
-    ("rsplitn", 2),
-    ("matches", 1),
-    ("rmatches", 1),
-    ("match_indices", 1),
-    ("rmatch_indices", 1),
-    ("trim_start_matches", 1),
-    ("trim_end_matches", 1),
-];
-
 #[derive(Clone, Copy, PartialEq, Debug)]
 enum SelfKind {
     Value,

src/tools/clippy/clippy_lints/src/methods/single_char_pattern.rs

@@ -9,9 +9,31 @@ use rustc_span::symbol::Symbol;
 
 use super::SINGLE_CHAR_PATTERN;
 
+const PATTERN_METHODS: [(&str, usize); 19] = [
+    ("contains", 1),
+    ("starts_with", 1),
+    ("ends_with", 1),
+    ("find", 1),
+    ("rfind", 1),
+    ("split", 1),
+    ("rsplit", 1),
+    ("split_terminator", 1),
+    ("rsplit_terminator", 1),
+    ("splitn", 2),
+    ("rsplitn", 2),
+    ("matches", 1),
+    ("rmatches", 1),
+    ("match_indices", 1),
+    ("rmatch_indices", 1),
+    ("strip_prefix", 1),
+    ("strip_suffix", 1),
+    ("trim_start_matches", 1),
+    ("trim_end_matches", 1),
+];
+
 /// lint for length-1 `str`s for methods in `PATTERN_METHODS`
 pub(super) fn check(cx: &LateContext<'_>, _expr: &hir::Expr<'_>, method_name: Symbol, args: &[hir::Expr<'_>]) {
-    for &(method, pos) in &crate::methods::PATTERN_METHODS {
+    for &(method, pos) in &PATTERN_METHODS {
         if_chain! {
             if let ty::Ref(_, ty, _) = cx.typeck_results().expr_ty_adjusted(&args[0]).kind();
             if *ty.kind() == ty::Str;

src/tools/clippy/clippy_lints/src/methods/unnecessary_filter_map.rs

@@ -6,6 +6,7 @@ use rustc_hir::intravisit::{walk_expr, NestedVisitorMap, Visitor};
 use rustc_hir::LangItem::{OptionNone, OptionSome};
 use rustc_lint::LateContext;
 use rustc_middle::hir::map::Map;
+use rustc_middle::ty::{self, TyS};
 use rustc_span::sym;
 
 use super::UNNECESSARY_FILTER_MAP;
@@ -28,25 +29,28 @@ pub(super) fn check(cx: &LateContext<'_>, expr: &hir::Expr<'_>, arg: &hir::Expr<
         found_mapping |= return_visitor.found_mapping;
         found_filtering |= return_visitor.found_filtering;
 
-        if !found_filtering {
+        let sugg = if !found_filtering {
-            span_lint(
+            "map"
-                cx,
+        } else if !found_mapping && !mutates_arg {
-                UNNECESSARY_FILTER_MAP,
+            let in_ty = cx.typeck_results().node_type(body.params[0].hir_id);
-                expr.span,
+            match cx.typeck_results().expr_ty(&body.value).kind() {
-                "this `.filter_map` can be written more simply using `.map`",
+                ty::Adt(adt, subst)
-            );
+                    if cx.tcx.is_diagnostic_item(sym::option_type, adt.did)
+                        && TyS::same_type(in_ty, subst.type_at(0)) =>
+                {
+                    "filter"
+                },
+                _ => return,
+            }
+        } else {
             return;
-        }
+        };
-
+        span_lint(
-        if !found_mapping && !mutates_arg {
+            cx,
-            span_lint(
+            UNNECESSARY_FILTER_MAP,
-                cx,
+            expr.span,
-                UNNECESSARY_FILTER_MAP,
+            &format!("this `.filter_map` can be written more simply using `.{}`", sugg),
-                expr.span,
+        );
-                "this `.filter_map` can be written more simply using `.filter`",
-            );
-            return;
-        }
     }
 }
 

src/tools/clippy/clippy_lints/src/misc_early.rs

@@ -1,569 +0,0 @@
-use clippy_utils::diagnostics::{span_lint, span_lint_and_help, span_lint_and_sugg, span_lint_and_then};
-use clippy_utils::source::snippet_opt;
-use rustc_ast::ast::{
-    BindingMode, Expr, ExprKind, GenericParamKind, Generics, Lit, LitFloatType, LitIntType, LitKind, Mutability,
-    NodeId, Pat, PatKind, UnOp,
-};
-use rustc_ast::visit::FnKind;
-use rustc_data_structures::fx::FxHashMap;
-use rustc_errors::Applicability;
-use rustc_hir::PrimTy;
-use rustc_lint::{EarlyContext, EarlyLintPass, LintContext};
-use rustc_middle::lint::in_external_macro;
-use rustc_session::{declare_lint_pass, declare_tool_lint};
-use rustc_span::source_map::Span;
-
-declare_clippy_lint! {
-    /// **What it does:** Checks for structure field patterns bound to wildcards.
-    ///
-    /// **Why is this bad?** Using `..` instead is shorter and leaves the focus on
-    /// the fields that are actually bound.
-    ///
-    /// **Known problems:** None.
-    ///
-    /// **Example:**
-    /// ```rust
-    /// # struct Foo {
-    /// #     a: i32,
-    /// #     b: i32,
-    /// #     c: i32,
-    /// # }
-    /// let f = Foo { a: 0, b: 0, c: 0 };
-    ///
-    /// // Bad
-    /// match f {
-    ///     Foo { a: _, b: 0, .. } => {},
-    ///     Foo { a: _, b: _, c: _ } => {},
-    /// }
-    ///
-    /// // Good
-    /// match f {
-    ///     Foo { b: 0, .. } => {},
-    ///     Foo { .. } => {},
-    /// }
-    /// ```
-    pub UNNEEDED_FIELD_PATTERN,
-    restriction,
-    "struct fields bound to a wildcard instead of using `..`"
-}
-
-declare_clippy_lint! {
-    /// **What it does:** Checks for function arguments having the similar names
-    /// differing by an underscore.
-    ///
-    /// **Why is this bad?** It affects code readability.
-    ///
-    /// **Known problems:** None.
-    ///
-    /// **Example:**
-    /// ```rust
-    /// // Bad
-    /// fn foo(a: i32, _a: i32) {}
-    ///
-    /// // Good
-    /// fn bar(a: i32, _b: i32) {}
-    /// ```
-    pub DUPLICATE_UNDERSCORE_ARGUMENT,
-    style,
-    "function arguments having names which only differ by an underscore"
-}
-
-declare_clippy_lint! {
-    /// **What it does:** Detects expressions of the form `--x`.
-    ///
-    /// **Why is this bad?** It can mislead C/C++ programmers to think `x` was
-    /// decremented.
-    ///
-    /// **Known problems:** None.
-    ///
-    /// **Example:**
-    /// ```rust
-    /// let mut x = 3;
-    /// --x;
-    /// ```
-    pub DOUBLE_NEG,
-    style,
-    "`--x`, which is a double negation of `x` and not a pre-decrement as in C/C++"
-}
-
-declare_clippy_lint! {
-    /// **What it does:** Warns on hexadecimal literals with mixed-case letter
-    /// digits.
-    ///
-    /// **Why is this bad?** It looks confusing.
-    ///
-    /// **Known problems:** None.
-    ///
-    /// **Example:**
-    /// ```rust
-    /// // Bad
-    /// let y = 0x1a9BAcD;
-    ///
-    /// // Good
-    /// let y = 0x1A9BACD;
-    /// ```
-    pub MIXED_CASE_HEX_LITERALS,
-    style,
-    "hex literals whose letter digits are not consistently upper- or lowercased"
-}
-
-declare_clippy_lint! {
-    /// **What it does:** Warns if literal suffixes are not separated by an
-    /// underscore.
-    ///
-    /// **Why is this bad?** It is much less readable.
-    ///
-    /// **Known problems:** None.
-    ///
-    /// **Example:**
-    /// ```rust
-    /// // Bad
-    /// let y = 123832i32;
-    ///
-    /// // Good
-    /// let y = 123832_i32;
-    /// ```
-    pub UNSEPARATED_LITERAL_SUFFIX,
-    pedantic,
-    "literals whose suffix is not separated by an underscore"
-}
-
-declare_clippy_lint! {
-    /// **What it does:** Warns if an integral constant literal starts with `0`.
-    ///
-    /// **Why is this bad?** In some languages (including the infamous C language
-    /// and most of its
-    /// family), this marks an octal constant. In Rust however, this is a decimal
-    /// constant. This could
-    /// be confusing for both the writer and a reader of the constant.
-    ///
-    /// **Known problems:** None.
-    ///
-    /// **Example:**
-    ///
-    /// In Rust:
-    /// ```rust
-    /// fn main() {
-    ///     let a = 0123;
-    ///     println!("{}", a);
-    /// }
-    /// ```
-    ///
-    /// prints `123`, while in C:
-    ///
-    /// ```c
-    /// #include <stdio.h>
-    ///
-    /// int main() {
-    ///     int a = 0123;
-    ///     printf("%d\n", a);
-    /// }
-    /// ```
-    ///
-    /// prints `83` (as `83 == 0o123` while `123 == 0o173`).
-    pub ZERO_PREFIXED_LITERAL,
-    complexity,
-    "integer literals starting with `0`"
-}
-
-declare_clippy_lint! {
-    /// **What it does:** Warns if a generic shadows a built-in type.
-    ///
-    /// **Why is this bad?** This gives surprising type errors.
-    ///
-    /// **Known problems:** None.
-    ///
-    /// **Example:**
-    ///
-    /// ```ignore
-    /// impl<u32> Foo<u32> {
-    ///     fn impl_func(&self) -> u32 {
-    ///         42
-    ///     }
-    /// }
-    /// ```
-    pub BUILTIN_TYPE_SHADOW,
-    style,
-    "shadowing a builtin type"
-}
-
-declare_clippy_lint! {
-    /// **What it does:** Checks for patterns in the form `name @ _`.
-    ///
-    /// **Why is this bad?** It's almost always more readable to just use direct
-    /// bindings.
-    ///
-    /// **Known problems:** None.
-    ///
-    /// **Example:**
-    /// ```rust
-    /// # let v = Some("abc");
-    ///
-    /// // Bad
-    /// match v {
-    ///     Some(x) => (),
-    ///     y @ _ => (),
-    /// }
-    ///
-    /// // Good
-    /// match v {
-    ///     Some(x) => (),
-    ///     y => (),
-    /// }
-    /// ```
-    pub REDUNDANT_PATTERN,
-    style,
-    "using `name @ _` in a pattern"
-}
-
-declare_clippy_lint! {
-    /// **What it does:** Checks for tuple patterns with a wildcard
-    /// pattern (`_`) is next to a rest pattern (`..`).
-    ///
-    /// _NOTE_: While `_, ..` means there is at least one element left, `..`
-    /// means there are 0 or more elements left. This can make a difference
-    /// when refactoring, but shouldn't result in errors in the refactored code,
-    /// since the wildcard pattern isn't used anyway.
-    /// **Why is this bad?** The wildcard pattern is unneeded as the rest pattern
-    /// can match that element as well.
-    ///
-    /// **Known problems:** None.
-    ///
-    /// **Example:**
-    /// ```rust
-    /// # struct TupleStruct(u32, u32, u32);
-    /// # let t = TupleStruct(1, 2, 3);
-    /// // Bad
-    /// match t {
-    ///     TupleStruct(0, .., _) => (),
-    ///     _ => (),
-    /// }
-    ///
-    /// // Good
-    /// match t {
-    ///     TupleStruct(0, ..) => (),
-    ///     _ => (),
-    /// }
-    /// ```
-    pub UNNEEDED_WILDCARD_PATTERN,
-    complexity,
-    "tuple patterns with a wildcard pattern (`_`) is next to a rest pattern (`..`)"
-}
-
-declare_lint_pass!(MiscEarlyLints => [
-    UNNEEDED_FIELD_PATTERN,
-    DUPLICATE_UNDERSCORE_ARGUMENT,
-    DOUBLE_NEG,
-    MIXED_CASE_HEX_LITERALS,
-    UNSEPARATED_LITERAL_SUFFIX,
-    ZERO_PREFIXED_LITERAL,
-    BUILTIN_TYPE_SHADOW,
-    REDUNDANT_PATTERN,
-    UNNEEDED_WILDCARD_PATTERN,
-]);
-
-impl EarlyLintPass for MiscEarlyLints {
-    fn check_generics(&mut self, cx: &EarlyContext<'_>, gen: &Generics) {
-        for param in &gen.params {
-            if let GenericParamKind::Type { .. } = param.kind {
-                if let Some(prim_ty) = PrimTy::from_name(param.ident.name) {
-                    span_lint(
-                        cx,
-                        BUILTIN_TYPE_SHADOW,
-                        param.ident.span,
-                        &format!("this generic shadows the built-in type `{}`", prim_ty.name()),
-                    );
-                }
-            }
-        }
-    }
-
-    fn check_pat(&mut self, cx: &EarlyContext<'_>, pat: &Pat) {
-        if let PatKind::Struct(ref npat, ref pfields, _) = pat.kind {
-            let mut wilds = 0;
-            let type_name = npat
-                .segments
-                .last()
-                .expect("A path must have at least one segment")
-                .ident
-                .name;
-
-            for field in pfields {
-                if let PatKind::Wild = field.pat.kind {
-                    wilds += 1;
-                }
-            }
-            if !pfields.is_empty() && wilds == pfields.len() {
-                span_lint_and_help(
-                    cx,
-                    UNNEEDED_FIELD_PATTERN,
-                    pat.span,
-                    "all the struct fields are matched to a wildcard pattern, consider using `..`",
-                    None,
-                    &format!("try with `{} {{ .. }}` instead", type_name),
-                );
-                return;
-            }
-            if wilds > 0 {
-                for field in pfields {
-                    if let PatKind::Wild = field.pat.kind {
-                        wilds -= 1;
-                        if wilds > 0 {
-                            span_lint(
-                                cx,
-                                UNNEEDED_FIELD_PATTERN,
-                                field.span,
-                                "you matched a field with a wildcard pattern, consider using `..` instead",
-                            );
-                        } else {
-                            let mut normal = vec![];
-
-                            for field in pfields {
-                                match field.pat.kind {
-                                    PatKind::Wild => {},
-                                    _ => {
-                                        if let Ok(n) = cx.sess().source_map().span_to_snippet(field.span) {
-                                            normal.push(n);
-                                        }
-                                    },
-                                }
-                            }
-
-                            span_lint_and_help(
-                                cx,
-                                UNNEEDED_FIELD_PATTERN,
-                                field.span,
-                                "you matched a field with a wildcard pattern, consider using `..` \
-                                 instead",
-                                None,
-                                &format!("try with `{} {{ {}, .. }}`", type_name, normal[..].join(", ")),
-                            );
-                        }
-                    }
-                }
-            }
-        }
-
-        if let PatKind::Ident(left, ident, Some(ref right)) = pat.kind {
-            let left_binding = match left {
-                BindingMode::ByRef(Mutability::Mut) => "ref mut ",
-                BindingMode::ByRef(Mutability::Not) => "ref ",
-                BindingMode::ByValue(..) => "",
-            };
-
-            if let PatKind::Wild = right.kind {
-                span_lint_and_sugg(
-                    cx,
-                    REDUNDANT_PATTERN,
-                    pat.span,
-                    &format!(
-                        "the `{} @ _` pattern can be written as just `{}`",
-                        ident.name, ident.name,
-                    ),
-                    "try",
-                    format!("{}{}", left_binding, ident.name),
-                    Applicability::MachineApplicable,
-                );
-            }
-        }
-
-        check_unneeded_wildcard_pattern(cx, pat);
-    }
-
-    fn check_fn(&mut self, cx: &EarlyContext<'_>, fn_kind: FnKind<'_>, _: Span, _: NodeId) {
-        let mut registered_names: FxHashMap<String, Span> = FxHashMap::default();
-
-        for arg in &fn_kind.decl().inputs {
-            if let PatKind::Ident(_, ident, None) = arg.pat.kind {
-                let arg_name = ident.to_string();
-
-                if let Some(arg_name) = arg_name.strip_prefix('_') {
-                    if let Some(correspondence) = registered_names.get(arg_name) {
-                        span_lint(
-                            cx,
-                            DUPLICATE_UNDERSCORE_ARGUMENT,
-                            *correspondence,
-                            &format!(
-                                "`{}` already exists, having another argument having almost the same \
-                                 name makes code comprehension and documentation more difficult",
-                                arg_name
-                            ),
-                        );
-                    }
-                } else {
-                    registered_names.insert(arg_name, arg.pat.span);
-                }
-            }
-        }
-    }
-
-    fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &Expr) {
-        if in_external_macro(cx.sess(), expr.span) {
-            return;
-        }
-        match expr.kind {
-            ExprKind::Unary(UnOp::Neg, ref inner) => {
-                if let ExprKind::Unary(UnOp::Neg, _) = inner.kind {
-                    span_lint(
-                        cx,
-                        DOUBLE_NEG,
-                        expr.span,
-                        "`--x` could be misinterpreted as pre-decrement by C programmers, is usually a no-op",
-                    );
-                }
-            },
-            ExprKind::Lit(ref lit) => Self::check_lit(cx, lit),
-            _ => (),
-        }
-    }
-}
-
-impl MiscEarlyLints {
-    fn check_lit(cx: &EarlyContext<'_>, lit: &Lit) {
-        // We test if first character in snippet is a number, because the snippet could be an expansion
-        // from a built-in macro like `line!()` or a proc-macro like `#[wasm_bindgen]`.
-        // Note that this check also covers special case that `line!()` is eagerly expanded by compiler.
-        // See <https://github.com/rust-lang/rust-clippy/issues/4507> for a regression.
-        // FIXME: Find a better way to detect those cases.
-        let lit_snip = match snippet_opt(cx, lit.span) {
-            Some(snip) if snip.chars().next().map_or(false, |c| c.is_digit(10)) => snip,
-            _ => return,
-        };
-
-        if let LitKind::Int(value, lit_int_type) = lit.kind {
-            let suffix = match lit_int_type {
-                LitIntType::Signed(ty) => ty.name_str(),
-                LitIntType::Unsigned(ty) => ty.name_str(),
-                LitIntType::Unsuffixed => "",
-            };
-
-            let maybe_last_sep_idx = if let Some(val) = lit_snip.len().checked_sub(suffix.len() + 1) {
-                val
-            } else {
-                return; // It's useless so shouldn't lint.
-            };
-            // Do not lint when literal is unsuffixed.
-            if !suffix.is_empty() && lit_snip.as_bytes()[maybe_last_sep_idx] != b'_' {
-                span_lint_and_sugg(
-                    cx,
-                    UNSEPARATED_LITERAL_SUFFIX,
-                    lit.span,
-                    "integer type suffix should be separated by an underscore",
-                    "add an underscore",
-                    format!("{}_{}", &lit_snip[..=maybe_last_sep_idx], suffix),
-                    Applicability::MachineApplicable,
-                );
-            }
-
-            if lit_snip.starts_with("0x") {
-                if maybe_last_sep_idx <= 2 {
-                    // It's meaningless or causes range error.
-                    return;
-                }
-                let mut seen = (false, false);
-                for ch in lit_snip.as_bytes()[2..=maybe_last_sep_idx].iter() {
-                    match ch {
-                        b'a'..=b'f' => seen.0 = true,
-                        b'A'..=b'F' => seen.1 = true,
-                        _ => {},
-                    }
-                    if seen.0 && seen.1 {
-                        span_lint(
-                            cx,
-                            MIXED_CASE_HEX_LITERALS,
-                            lit.span,
-                            "inconsistent casing in hexadecimal literal",
-                        );
-                        break;
-                    }
-                }
-            } else if lit_snip.starts_with("0b") || lit_snip.starts_with("0o") {
-                /* nothing to do */
-            } else if value != 0 && lit_snip.starts_with('0') {
-                span_lint_and_then(
-                    cx,
-                    ZERO_PREFIXED_LITERAL,
-                    lit.span,
-                    "this is a decimal constant",
-                    |diag| {
-                        diag.span_suggestion(
-                            lit.span,
-                            "if you mean to use a decimal constant, remove the `0` to avoid confusion",
-                            lit_snip.trim_start_matches(|c| c == '_' || c == '0').to_string(),
-                            Applicability::MaybeIncorrect,
-                        );
-                        diag.span_suggestion(
-                            lit.span,
-                            "if you mean to use an octal constant, use `0o`",
-                            format!("0o{}", lit_snip.trim_start_matches(|c| c == '_' || c == '0')),
-                            Applicability::MaybeIncorrect,
-                        );
-                    },
-                );
-            }
-        } else if let LitKind::Float(_, LitFloatType::Suffixed(float_ty)) = lit.kind {
-            let suffix = float_ty.name_str();
-            let maybe_last_sep_idx = if let Some(val) = lit_snip.len().checked_sub(suffix.len() + 1) {
-                val
-            } else {
-                return; // It's useless so shouldn't lint.
-            };
-            if lit_snip.as_bytes()[maybe_last_sep_idx] != b'_' {
-                span_lint_and_sugg(
-                    cx,
-                    UNSEPARATED_LITERAL_SUFFIX,
-                    lit.span,
-                    "float type suffix should be separated by an underscore",
-                    "add an underscore",
-                    format!("{}_{}", &lit_snip[..=maybe_last_sep_idx], suffix),
-                    Applicability::MachineApplicable,
-                );
-            }
-        }
-    }
-}
-
-fn check_unneeded_wildcard_pattern(cx: &EarlyContext<'_>, pat: &Pat) {
-    if let PatKind::TupleStruct(_, ref patterns) | PatKind::Tuple(ref patterns) = pat.kind {
-        fn span_lint(cx: &EarlyContext<'_>, span: Span, only_one: bool) {
-            span_lint_and_sugg(
-                cx,
-                UNNEEDED_WILDCARD_PATTERN,
-                span,
-                if only_one {
-                    "this pattern is unneeded as the `..` pattern can match that element"
-                } else {
-                    "these patterns are unneeded as the `..` pattern can match those elements"
-                },
-                if only_one { "remove it" } else { "remove them" },
-                "".to_string(),
-                Applicability::MachineApplicable,
-            );
-        }
-
-        if let Some(rest_index) = patterns.iter().position(|pat| pat.is_rest()) {
-            if let Some((left_index, left_pat)) = patterns[..rest_index]
-                .iter()
-                .rev()
-                .take_while(|pat| matches!(pat.kind, PatKind::Wild))
-                .enumerate()
-                .last()
-            {
-                span_lint(cx, left_pat.span.until(patterns[rest_index].span), left_index == 0);
-            }
-
-            if let Some((right_index, right_pat)) = patterns[rest_index + 1..]
-                .iter()
-                .take_while(|pat| matches!(pat.kind, PatKind::Wild))
-                .enumerate()
-                .last()
-            {
-                span_lint(
-                    cx,
-                    patterns[rest_index].span.shrink_to_hi().to(right_pat.span),
-                    right_index == 0,
-                );
-            }
-        }
-    }
-}

src/tools/clippy/clippy_lints/src/misc_early/builtin_type_shadow.rs

@@ -0,0 +1,19 @@
+use clippy_utils::diagnostics::span_lint;
+use rustc_ast::ast::{GenericParam, GenericParamKind};
+use rustc_hir::PrimTy;
+use rustc_lint::EarlyContext;
+
+use super::BUILTIN_TYPE_SHADOW;
+
+pub(super) fn check(cx: &EarlyContext<'_>, param: &GenericParam) {
+    if let GenericParamKind::Type { .. } = param.kind {
+        if let Some(prim_ty) = PrimTy::from_name(param.ident.name) {
+            span_lint(
+                cx,
+                BUILTIN_TYPE_SHADOW,
+                param.ident.span,
+                &format!("this generic shadows the built-in type `{}`", prim_ty.name()),
+            );
+        }
+    }
+}

src/tools/clippy/clippy_lints/src/misc_early/double_neg.rs

@@ -0,0 +1,23 @@
+use super::MiscEarlyLints;
+use clippy_utils::diagnostics::span_lint;
+use rustc_ast::ast::{Expr, ExprKind, UnOp};
+use rustc_lint::EarlyContext;
+
+use super::DOUBLE_NEG;
+
+pub(super) fn check(cx: &EarlyContext<'_>, expr: &Expr) {
+    match expr.kind {
+        ExprKind::Unary(UnOp::Neg, ref inner) => {
+            if let ExprKind::Unary(UnOp::Neg, _) = inner.kind {
+                span_lint(
+                    cx,
+                    DOUBLE_NEG,
+                    expr.span,
+                    "`--x` could be misinterpreted as pre-decrement by C programmers, is usually a no-op",
+                );
+            }
+        },
+        ExprKind::Lit(ref lit) => MiscEarlyLints::check_lit(cx, lit),
+        _ => (),
+    }
+}

src/tools/clippy/clippy_lints/src/misc_early/mixed_case_hex_literals.rs

@@ -0,0 +1,34 @@
+use clippy_utils::diagnostics::span_lint;
+use rustc_ast::ast::Lit;
+use rustc_lint::EarlyContext;
+
+use super::MIXED_CASE_HEX_LITERALS;
+
+pub(super) fn check(cx: &EarlyContext<'_>, lit: &Lit, suffix: &str, lit_snip: &str) {
+    let maybe_last_sep_idx = if let Some(val) = lit_snip.len().checked_sub(suffix.len() + 1) {
+        val
+    } else {
+        return; // It's useless so shouldn't lint.
+    };
+    if maybe_last_sep_idx <= 2 {
+        // It's meaningless or causes range error.
+        return;
+    }
+    let mut seen = (false, false);
+    for ch in lit_snip.as_bytes()[2..=maybe_last_sep_idx].iter() {
+        match ch {
+            b'a'..=b'f' => seen.0 = true,
+            b'A'..=b'F' => seen.1 = true,
+            _ => {},
+        }
+        if seen.0 && seen.1 {
+            span_lint(
+                cx,
+                MIXED_CASE_HEX_LITERALS,
+                lit.span,
+                "inconsistent casing in hexadecimal literal",
+            );
+            break;
+        }
+    }
+}

src/tools/clippy/clippy_lints/src/misc_early/mod.rs

@@ -0,0 +1,348 @@
+mod builtin_type_shadow;
+mod double_neg;
+mod mixed_case_hex_literals;
+mod redundant_pattern;
+mod unneeded_field_pattern;
+mod unneeded_wildcard_pattern;
+mod unseparated_literal_suffix;
+mod zero_prefixed_literal;
+
+use clippy_utils::diagnostics::span_lint;
+use clippy_utils::source::snippet_opt;
+use rustc_ast::ast::{Expr, Generics, Lit, LitFloatType, LitIntType, LitKind, NodeId, Pat, PatKind};
+use rustc_ast::visit::FnKind;
+use rustc_data_structures::fx::FxHashMap;
+use rustc_lint::{EarlyContext, EarlyLintPass, LintContext};
+use rustc_middle::lint::in_external_macro;
+use rustc_session::{declare_lint_pass, declare_tool_lint};
+use rustc_span::source_map::Span;
+
+declare_clippy_lint! {
+    /// **What it does:** Checks for structure field patterns bound to wildcards.
+    ///
+    /// **Why is this bad?** Using `..` instead is shorter and leaves the focus on
+    /// the fields that are actually bound.
+    ///
+    /// **Known problems:** None.
+    ///
+    /// **Example:**
+    /// ```rust
+    /// # struct Foo {
+    /// #     a: i32,
+    /// #     b: i32,
+    /// #     c: i32,
+    /// # }
+    /// let f = Foo { a: 0, b: 0, c: 0 };
+    ///
+    /// // Bad
+    /// match f {
+    ///     Foo { a: _, b: 0, .. } => {},
+    ///     Foo { a: _, b: _, c: _ } => {},
+    /// }
+    ///
+    /// // Good
+    /// match f {
+    ///     Foo { b: 0, .. } => {},
+    ///     Foo { .. } => {},
+    /// }
+    /// ```
+    pub UNNEEDED_FIELD_PATTERN,
+    restriction,
+    "struct fields bound to a wildcard instead of using `..`"
+}
+
+declare_clippy_lint! {
+    /// **What it does:** Checks for function arguments having the similar names
+    /// differing by an underscore.
+    ///
+    /// **Why is this bad?** It affects code readability.
+    ///
+    /// **Known problems:** None.
+    ///
+    /// **Example:**
+    /// ```rust
+    /// // Bad
+    /// fn foo(a: i32, _a: i32) {}
+    ///
+    /// // Good
+    /// fn bar(a: i32, _b: i32) {}
+    /// ```
+    pub DUPLICATE_UNDERSCORE_ARGUMENT,
+    style,
+    "function arguments having names which only differ by an underscore"
+}
+
+declare_clippy_lint! {
+    /// **What it does:** Detects expressions of the form `--x`.
+    ///
+    /// **Why is this bad?** It can mislead C/C++ programmers to think `x` was
+    /// decremented.
+    ///
+    /// **Known problems:** None.
+    ///
+    /// **Example:**
+    /// ```rust
+    /// let mut x = 3;
+    /// --x;
+    /// ```
+    pub DOUBLE_NEG,
+    style,
+    "`--x`, which is a double negation of `x` and not a pre-decrement as in C/C++"
+}
+
+declare_clippy_lint! {
+    /// **What it does:** Warns on hexadecimal literals with mixed-case letter
+    /// digits.
+    ///
+    /// **Why is this bad?** It looks confusing.
+    ///
+    /// **Known problems:** None.
+    ///
+    /// **Example:**
+    /// ```rust
+    /// // Bad
+    /// let y = 0x1a9BAcD;
+    ///
+    /// // Good
+    /// let y = 0x1A9BACD;
+    /// ```
+    pub MIXED_CASE_HEX_LITERALS,
+    style,
+    "hex literals whose letter digits are not consistently upper- or lowercased"
+}
+
+declare_clippy_lint! {
+    /// **What it does:** Warns if literal suffixes are not separated by an
+    /// underscore.
+    ///
+    /// **Why is this bad?** It is much less readable.
+    ///
+    /// **Known problems:** None.
+    ///
+    /// **Example:**
+    /// ```rust
+    /// // Bad
+    /// let y = 123832i32;
+    ///
+    /// // Good
+    /// let y = 123832_i32;
+    /// ```
+    pub UNSEPARATED_LITERAL_SUFFIX,
+    pedantic,
+    "literals whose suffix is not separated by an underscore"
+}
+
+declare_clippy_lint! {
+    /// **What it does:** Warns if an integral constant literal starts with `0`.
+    ///
+    /// **Why is this bad?** In some languages (including the infamous C language
+    /// and most of its
+    /// family), this marks an octal constant. In Rust however, this is a decimal
+    /// constant. This could
+    /// be confusing for both the writer and a reader of the constant.
+    ///
+    /// **Known problems:** None.
+    ///
+    /// **Example:**
+    ///
+    /// In Rust:
+    /// ```rust
+    /// fn main() {
+    ///     let a = 0123;
+    ///     println!("{}", a);
+    /// }
+    /// ```
+    ///
+    /// prints `123`, while in C:
+    ///
+    /// ```c
+    /// #include <stdio.h>
+    ///
+    /// int main() {
+    ///     int a = 0123;
+    ///     printf("%d\n", a);
+    /// }
+    /// ```
+    ///
+    /// prints `83` (as `83 == 0o123` while `123 == 0o173`).
+    pub ZERO_PREFIXED_LITERAL,
+    complexity,
+    "integer literals starting with `0`"
+}
+
+declare_clippy_lint! {
+    /// **What it does:** Warns if a generic shadows a built-in type.
+    ///
+    /// **Why is this bad?** This gives surprising type errors.
+    ///
+    /// **Known problems:** None.
+    ///
+    /// **Example:**
+    ///
+    /// ```ignore
+    /// impl<u32> Foo<u32> {
+    ///     fn impl_func(&self) -> u32 {
+    ///         42
+    ///     }
+    /// }
+    /// ```
+    pub BUILTIN_TYPE_SHADOW,
+    style,
+    "shadowing a builtin type"
+}
+
+declare_clippy_lint! {
+    /// **What it does:** Checks for patterns in the form `name @ _`.
+    ///
+    /// **Why is this bad?** It's almost always more readable to just use direct
+    /// bindings.
+    ///
+    /// **Known problems:** None.
+    ///
+    /// **Example:**
+    /// ```rust
+    /// # let v = Some("abc");
+    ///
+    /// // Bad
+    /// match v {
+    ///     Some(x) => (),
+    ///     y @ _ => (),
+    /// }
+    ///
+    /// // Good
+    /// match v {
+    ///     Some(x) => (),
+    ///     y => (),
+    /// }
+    /// ```
+    pub REDUNDANT_PATTERN,
+    style,
+    "using `name @ _` in a pattern"
+}
+
+declare_clippy_lint! {
+    /// **What it does:** Checks for tuple patterns with a wildcard
+    /// pattern (`_`) is next to a rest pattern (`..`).
+    ///
+    /// _NOTE_: While `_, ..` means there is at least one element left, `..`
+    /// means there are 0 or more elements left. This can make a difference
+    /// when refactoring, but shouldn't result in errors in the refactored code,
+    /// since the wildcard pattern isn't used anyway.
+    /// **Why is this bad?** The wildcard pattern is unneeded as the rest pattern
+    /// can match that element as well.
+    ///
+    /// **Known problems:** None.
+    ///
+    /// **Example:**
+    /// ```rust
+    /// # struct TupleStruct(u32, u32, u32);
+    /// # let t = TupleStruct(1, 2, 3);
+    /// // Bad
+    /// match t {
+    ///     TupleStruct(0, .., _) => (),
+    ///     _ => (),
+    /// }
+    ///
+    /// // Good
+    /// match t {
+    ///     TupleStruct(0, ..) => (),
+    ///     _ => (),
+    /// }
+    /// ```
+    pub UNNEEDED_WILDCARD_PATTERN,
+    complexity,
+    "tuple patterns with a wildcard pattern (`_`) is next to a rest pattern (`..`)"
+}
+
+declare_lint_pass!(MiscEarlyLints => [
+    UNNEEDED_FIELD_PATTERN,
+    DUPLICATE_UNDERSCORE_ARGUMENT,
+    DOUBLE_NEG,
+    MIXED_CASE_HEX_LITERALS,
+    UNSEPARATED_LITERAL_SUFFIX,
+    ZERO_PREFIXED_LITERAL,
+    BUILTIN_TYPE_SHADOW,
+    REDUNDANT_PATTERN,
+    UNNEEDED_WILDCARD_PATTERN,
+]);
+
+impl EarlyLintPass for MiscEarlyLints {
+    fn check_generics(&mut self, cx: &EarlyContext<'_>, gen: &Generics) {
+        for param in &gen.params {
+            builtin_type_shadow::check(cx, param);
+        }
+    }
+
+    fn check_pat(&mut self, cx: &EarlyContext<'_>, pat: &Pat) {
+        unneeded_field_pattern::check(cx, pat);
+        redundant_pattern::check(cx, pat);
+        unneeded_wildcard_pattern::check(cx, pat);
+    }
+
+    fn check_fn(&mut self, cx: &EarlyContext<'_>, fn_kind: FnKind<'_>, _: Span, _: NodeId) {
+        let mut registered_names: FxHashMap<String, Span> = FxHashMap::default();
+
+        for arg in &fn_kind.decl().inputs {
+            if let PatKind::Ident(_, ident, None) = arg.pat.kind {
+                let arg_name = ident.to_string();
+
+                if let Some(arg_name) = arg_name.strip_prefix('_') {
+                    if let Some(correspondence) = registered_names.get(arg_name) {
+                        span_lint(
+                            cx,
+                            DUPLICATE_UNDERSCORE_ARGUMENT,
+                            *correspondence,
+                            &format!(
+                                "`{}` already exists, having another argument having almost the same \
+                                 name makes code comprehension and documentation more difficult",
+                                arg_name
+                            ),
+                        );
+                    }
+                } else {
+                    registered_names.insert(arg_name, arg.pat.span);
+                }
+            }
+        }
+    }
+
+    fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &Expr) {
+        if in_external_macro(cx.sess(), expr.span) {
+            return;
+        }
+        double_neg::check(cx, expr)
+    }
+}
+
+impl MiscEarlyLints {
+    fn check_lit(cx: &EarlyContext<'_>, lit: &Lit) {
+        // We test if first character in snippet is a number, because the snippet could be an expansion
+        // from a built-in macro like `line!()` or a proc-macro like `#[wasm_bindgen]`.
+        // Note that this check also covers special case that `line!()` is eagerly expanded by compiler.
+        // See <https://github.com/rust-lang/rust-clippy/issues/4507> for a regression.
+        // FIXME: Find a better way to detect those cases.
+        let lit_snip = match snippet_opt(cx, lit.span) {
+            Some(snip) if snip.chars().next().map_or(false, |c| c.is_digit(10)) => snip,
+            _ => return,
+        };
+
+        if let LitKind::Int(value, lit_int_type) = lit.kind {
+            let suffix = match lit_int_type {
+                LitIntType::Signed(ty) => ty.name_str(),
+                LitIntType::Unsigned(ty) => ty.name_str(),
+                LitIntType::Unsuffixed => "",
+            };
+            unseparated_literal_suffix::check(cx, lit, &lit_snip, suffix, "integer");
+            if lit_snip.starts_with("0x") {
+                mixed_case_hex_literals::check(cx, lit, suffix, &lit_snip)
+            } else if lit_snip.starts_with("0b") || lit_snip.starts_with("0o") {
+                /* nothing to do */
+            } else if value != 0 && lit_snip.starts_with('0') {
+                zero_prefixed_literal::check(cx, lit, &lit_snip)
+            }
+        } else if let LitKind::Float(_, LitFloatType::Suffixed(float_ty)) = lit.kind {
+            let suffix = float_ty.name_str();
+            unseparated_literal_suffix::check(cx, lit, &lit_snip, suffix, "float")
+        }
+    }
+}

src/tools/clippy/clippy_lints/src/misc_early/redundant_pattern.rs

@@ -0,0 +1,31 @@
+use clippy_utils::diagnostics::span_lint_and_sugg;
+use rustc_ast::ast::{BindingMode, Mutability, Pat, PatKind};
+use rustc_errors::Applicability;
+use rustc_lint::EarlyContext;
+
+use super::REDUNDANT_PATTERN;
+
+pub(super) fn check(cx: &EarlyContext<'_>, pat: &Pat) {
+    if let PatKind::Ident(left, ident, Some(ref right)) = pat.kind {
+        let left_binding = match left {
+            BindingMode::ByRef(Mutability::Mut) => "ref mut ",
+            BindingMode::ByRef(Mutability::Not) => "ref ",
+            BindingMode::ByValue(..) => "",
+        };
+
+        if let PatKind::Wild = right.kind {
+            span_lint_and_sugg(
+                cx,
+                REDUNDANT_PATTERN,
+                pat.span,
+                &format!(
+                    "the `{} @ _` pattern can be written as just `{}`",
+                    ident.name, ident.name,
+                ),
+                "try",
+                format!("{}{}", left_binding, ident.name),
+                Applicability::MachineApplicable,
+            );
+        }
+    }
+}

src/tools/clippy/clippy_lints/src/misc_early/unneeded_field_pattern.rs

@@ -0,0 +1,72 @@
+use clippy_utils::diagnostics::{span_lint, span_lint_and_help};
+use rustc_ast::ast::{Pat, PatKind};
+use rustc_lint::{EarlyContext, LintContext};
+
+use super::UNNEEDED_FIELD_PATTERN;
+
+pub(super) fn check(cx: &EarlyContext<'_>, pat: &Pat) {
+    if let PatKind::Struct(ref npat, ref pfields, _) = pat.kind {
+        let mut wilds = 0;
+        let type_name = npat
+            .segments
+            .last()
+            .expect("A path must have at least one segment")
+            .ident
+            .name;
+
+        for field in pfields {
+            if let PatKind::Wild = field.pat.kind {
+                wilds += 1;
+            }
+        }
+        if !pfields.is_empty() && wilds == pfields.len() {
+            span_lint_and_help(
+                cx,
+                UNNEEDED_FIELD_PATTERN,
+                pat.span,
+                "all the struct fields are matched to a wildcard pattern, consider using `..`",
+                None,
+                &format!("try with `{} {{ .. }}` instead", type_name),
+            );
+            return;
+        }
+        if wilds > 0 {
+            for field in pfields {
+                if let PatKind::Wild = field.pat.kind {
+                    wilds -= 1;
+                    if wilds > 0 {
+                        span_lint(
+                            cx,
+                            UNNEEDED_FIELD_PATTERN,
+                            field.span,
+                            "you matched a field with a wildcard pattern, consider using `..` instead",
+                        );
+                    } else {
+                        let mut normal = vec![];
+
+                        for field in pfields {
+                            match field.pat.kind {
+                                PatKind::Wild => {},
+                                _ => {
+                                    if let Ok(n) = cx.sess().source_map().span_to_snippet(field.span) {
+                                        normal.push(n);
+                                    }
+                                },
+                            }
+                        }
+
+                        span_lint_and_help(
+                            cx,
+                            UNNEEDED_FIELD_PATTERN,
+                            field.span,
+                            "you matched a field with a wildcard pattern, consider using `..` \
+                             instead",
+                            None,
+                            &format!("try with `{} {{ {}, .. }}`", type_name, normal[..].join(", ")),
+                        );
+                    }
+                }
+            }
+        }
+    }
+}

src/tools/clippy/clippy_lints/src/misc_early/unneeded_wildcard_pattern.rs

@@ -0,0 +1,52 @@
+use clippy_utils::diagnostics::span_lint_and_sugg;
+use rustc_ast::ast::{Pat, PatKind};
+use rustc_errors::Applicability;
+use rustc_lint::EarlyContext;
+use rustc_span::source_map::Span;
+
+use super::UNNEEDED_WILDCARD_PATTERN;
+
+pub(super) fn check(cx: &EarlyContext<'_>, pat: &Pat) {
+    if let PatKind::TupleStruct(_, ref patterns) | PatKind::Tuple(ref patterns) = pat.kind {
+        if let Some(rest_index) = patterns.iter().position(|pat| pat.is_rest()) {
+            if let Some((left_index, left_pat)) = patterns[..rest_index]
+                .iter()
+                .rev()
+                .take_while(|pat| matches!(pat.kind, PatKind::Wild))
+                .enumerate()
+                .last()
+            {
+                span_lint(cx, left_pat.span.until(patterns[rest_index].span), left_index == 0);
+            }
+
+            if let Some((right_index, right_pat)) = patterns[rest_index + 1..]
+                .iter()
+                .take_while(|pat| matches!(pat.kind, PatKind::Wild))
+                .enumerate()
+                .last()
+            {
+                span_lint(
+                    cx,
+                    patterns[rest_index].span.shrink_to_hi().to(right_pat.span),
+                    right_index == 0,
+                );
+            }
+        }
+    }
+}
+
+fn span_lint(cx: &EarlyContext<'_>, span: Span, only_one: bool) {
+    span_lint_and_sugg(
+        cx,
+        UNNEEDED_WILDCARD_PATTERN,
+        span,
+        if only_one {
+            "this pattern is unneeded as the `..` pattern can match that element"
+        } else {
+            "these patterns are unneeded as the `..` pattern can match those elements"
+        },
+        if only_one { "remove it" } else { "remove them" },
+        "".to_string(),
+        Applicability::MachineApplicable,
+    );
+}

src/tools/clippy/clippy_lints/src/misc_early/unseparated_literal_suffix.rs

@@ -0,0 +1,26 @@
+use clippy_utils::diagnostics::span_lint_and_sugg;
+use rustc_ast::ast::Lit;
+use rustc_errors::Applicability;
+use rustc_lint::EarlyContext;
+
+use super::UNSEPARATED_LITERAL_SUFFIX;
+
+pub(super) fn check(cx: &EarlyContext<'_>, lit: &Lit, lit_snip: &str, suffix: &str, sugg_type: &str) {
+    let maybe_last_sep_idx = if let Some(val) = lit_snip.len().checked_sub(suffix.len() + 1) {
+        val
+    } else {
+        return; // It's useless so shouldn't lint.
+    };
+    // Do not lint when literal is unsuffixed.
+    if !suffix.is_empty() && lit_snip.as_bytes()[maybe_last_sep_idx] != b'_' {
+        span_lint_and_sugg(
+            cx,
+            UNSEPARATED_LITERAL_SUFFIX,
+            lit.span,
+            &format!("{} type suffix should be separated by an underscore", sugg_type),
+            "add an underscore",
+            format!("{}_{}", &lit_snip[..=maybe_last_sep_idx], suffix),
+            Applicability::MachineApplicable,
+        );
+    }
+}

src/tools/clippy/clippy_lints/src/misc_early/zero_prefixed_literal.rs

@@ -0,0 +1,29 @@
+use clippy_utils::diagnostics::span_lint_and_then;
+use rustc_ast::ast::Lit;
+use rustc_errors::Applicability;
+use rustc_lint::EarlyContext;
+
+use super::ZERO_PREFIXED_LITERAL;
+
+pub(super) fn check(cx: &EarlyContext<'_>, lit: &Lit, lit_snip: &str) {
+    span_lint_and_then(
+        cx,
+        ZERO_PREFIXED_LITERAL,
+        lit.span,
+        "this is a decimal constant",
+        |diag| {
+            diag.span_suggestion(
+                lit.span,
+                "if you mean to use a decimal constant, remove the `0` to avoid confusion",
+                lit_snip.trim_start_matches(|c| c == '_' || c == '0').to_string(),
+                Applicability::MaybeIncorrect,
+            );
+            diag.span_suggestion(
+                lit.span,
+                "if you mean to use an octal constant, use `0o`",
+                format!("0o{}", lit_snip.trim_start_matches(|c| c == '_' || c == '0')),
+                Applicability::MaybeIncorrect,
+            );
+        },
+    );
+}

src/tools/clippy/clippy_lints/src/slow_vector_initialization.rs

@@ -7,7 +7,7 @@ use rustc_ast::ast::LitKind;
 use rustc_errors::Applicability;
 use rustc_hir::intravisit::{walk_block, walk_expr, walk_stmt, NestedVisitorMap, Visitor};
 use rustc_hir::{BindingAnnotation, Block, Expr, ExprKind, HirId, PatKind, QPath, Stmt, StmtKind};
-use rustc_lint::{LateContext, LateLintPass, Lint};
+use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::hir::map::Map;
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::symbol::sym;
@@ -157,26 +157,16 @@ impl SlowVectorInit {
         vec_alloc: &VecAllocation<'_>,
     ) {
         match initialization {
-            InitializationType::Extend(e) | InitializationType::Resize(e) => Self::emit_lint(
+            InitializationType::Extend(e) | InitializationType::Resize(e) => {
-                cx,
+                Self::emit_lint(cx, e, vec_alloc, "slow zero-filling initialization")
-                e,
+            },
-                vec_alloc,
-                "slow zero-filling initialization",
-                SLOW_VECTOR_INITIALIZATION,
-            ),
         };
     }
 
-    fn emit_lint<'tcx>(
+    fn emit_lint<'tcx>(cx: &LateContext<'tcx>, slow_fill: &Expr<'_>, vec_alloc: &VecAllocation<'_>, msg: &str) {
-        cx: &LateContext<'tcx>,
-        slow_fill: &Expr<'_>,
-        vec_alloc: &VecAllocation<'_>,
-        msg: &str,
-        lint: &'static Lint,
-    ) {
         let len_expr = Sugg::hir(cx, vec_alloc.len_expr, "len");
 
-        span_lint_and_then(cx, lint, slow_fill.span, msg, |diag| {
+        span_lint_and_then(cx, SLOW_VECTOR_INITIALIZATION, slow_fill.span, msg, |diag| {
             diag.span_suggestion(
                 vec_alloc.allocation_expr.span,
                 "consider replace allocation with",

src/tools/clippy/clippy_lints/src/unused_unit.rs

@@ -47,7 +47,9 @@ impl EarlyLintPass for UnusedUnit {
         if_chain! {
             if let Some(stmt) = block.stmts.last();
             if let ast::StmtKind::Expr(ref expr) = stmt.kind;
-            if is_unit_expr(expr) && !stmt.span.from_expansion();
+            if is_unit_expr(expr);
+            let ctxt = block.span.ctxt();
+            if stmt.span.ctxt() == ctxt && expr.span.ctxt() == ctxt;
             then {
                 let sp = expr.span;
                 span_lint_and_sugg(

src/tools/clippy/clippy_lints/src/utils/conf.rs

@@ -1,121 +1,110 @@
 //! Read configurations files.
 
-#![deny(clippy::missing_docs_in_private_items)]
+#![allow(clippy::module_name_repetitions)]
 
-use rustc_ast::ast::{LitKind, MetaItemKind, NestedMetaItem};
+use serde::de::{Deserializer, IgnoredAny, IntoDeserializer, MapAccess, Visitor};
-use rustc_span::source_map;
+use serde::Deserialize;
-use source_map::Span;
+use std::error::Error;
-use std::lazy::SyncLazy;
 use std::path::{Path, PathBuf};
-use std::sync::Mutex;
 use std::{env, fmt, fs, io};
 
-/// Gets the configuration file from arguments.
+/// Conf with parse errors
-pub fn file_from_args(args: &[NestedMetaItem]) -> Result<Option<PathBuf>, (&'static str, Span)> {
+#[derive(Default)]
-    for arg in args.iter().filter_map(NestedMetaItem::meta_item) {
+pub struct TryConf {
-        if arg.has_name(sym!(conf_file)) {
+    pub conf: Conf,
-            return match arg.kind {
+    pub errors: Vec<String>,
-                MetaItemKind::Word | MetaItemKind::List(_) => Err(("`conf_file` must be a named value", arg.span)),
-                MetaItemKind::NameValue(ref value) => {
-                    if let LitKind::Str(ref file, _) = value.kind {
-                        Ok(Some(file.to_string().into()))
-                    } else {
-                        Err(("`conf_file` value must be a string", value.span))
-                    }
-                },
-            };
-        }
-    }
-
-    Ok(None)
 }
 
-/// Error from reading a configuration file.
+impl TryConf {
-#[derive(Debug)]
+    fn from_error(error: impl Error) -> Self {
-pub enum Error {
+        Self {
-    /// An I/O error.
+            conf: Conf::default(),
-    Io(io::Error),
+            errors: vec![error.to_string()],
-    /// Not valid toml or doesn't fit the expected config format
-    Toml(String),
-}
-
-impl fmt::Display for Error {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        match self {
-            Self::Io(err) => err.fmt(f),
-            Self::Toml(err) => err.fmt(f),
         }
     }
 }
 
-impl From<io::Error> for Error {
-    fn from(e: io::Error) -> Self {
-        Self::Io(e)
-    }
-}
-
-/// Vec of errors that might be collected during config toml parsing
-static ERRORS: SyncLazy<Mutex<Vec<Error>>> = SyncLazy::new(|| Mutex::new(Vec::new()));
-
 macro_rules! define_Conf {
-    ($(#[$doc:meta] ($config:ident, $config_str:literal: $Ty:ty, $default:expr),)+) => {
+    ($(
-        mod helpers {
+        #[$doc:meta]
-            use serde::Deserialize;
+        $(#[conf_deprecated($dep:literal)])?
-            /// Type used to store lint configuration.
+        ($name:ident: $ty:ty = $default:expr),
-            #[derive(Deserialize)]
+    )*) => {
-            #[serde(rename_all = "kebab-case", deny_unknown_fields)]
+        /// Clippy lint configuration
-            pub struct Conf {
+        pub struct Conf {
-                $(
+            $(#[$doc] pub $name: $ty,)*
-                    #[$doc]
+        }
-                    #[serde(default = $config_str)]
+
-                    #[serde(with = $config_str)]
+        mod defaults {
-                    pub $config: $Ty,
+            $(pub fn $name() -> $ty { $default })*
-                )+
+        }
-                #[allow(dead_code)]
+
-                #[serde(default)]
+        impl Default for Conf {
-                third_party: Option<::toml::Value>,
+            fn default() -> Self {
+                Self { $($name: defaults::$name(),)* }
+            }
+        }
+
+        impl<'de> Deserialize<'de> for TryConf {
+            fn deserialize<D>(deserializer: D) -> Result<Self, D::Error> where D: Deserializer<'de> {
+                deserializer.deserialize_map(ConfVisitor)
+            }
+        }
+
+        #[derive(Deserialize)]
+        #[serde(field_identifier, rename_all = "kebab-case")]
+        #[allow(non_camel_case_types)]
+        enum Field { $($name,)* third_party, }
+
+        struct ConfVisitor;
+
+        impl<'de> Visitor<'de> for ConfVisitor {
+            type Value = TryConf;
+
+            fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
+                formatter.write_str("Conf")
             }
 
-            $(
+            fn visit_map<V>(self, mut map: V) -> Result<Self::Value, V::Error> where V: MapAccess<'de> {
-                mod $config {
+                let mut errors = Vec::new();
-                    use serde::Deserialize;
+                $(let mut $name = None;)*
-                    pub fn deserialize<'de, D: serde::Deserializer<'de>>(deserializer: D) -> Result<$Ty, D::Error> {
+                // could get `Field` here directly, but get `str` first for diagnostics
-                        use super::super::{ERRORS, Error};
+                while let Some(name) = map.next_key::<&str>()? {
-
+                    match Field::deserialize(name.into_deserializer())? {
-                        Ok(
+                        $(Field::$name => {
-                            <$Ty>::deserialize(deserializer).unwrap_or_else(|e| {
+                            $(errors.push(format!("deprecated field `{}`. {}", name, $dep));)?
-                                ERRORS
+                            match map.next_value() {
-                                    .lock()
+                                Err(e) => errors.push(e.to_string()),
-                                    .expect("no threading here")
+                                Ok(value) => match $name {
-                                    .push(Error::Toml(e.to_string()));
+                                    Some(_) => errors.push(format!("duplicate field `{}`", name)),
-                                super::$config()
+                                    None => $name = Some(value),
-                            })
+                                }
-                        )
+                            }
+                        })*
+                        // white-listed; ignore
+                        Field::third_party => drop(map.next_value::<IgnoredAny>())
                     }
                 }
-
+                let conf = Conf { $($name: $name.unwrap_or_else(defaults::$name),)* };
-                #[must_use]
+                Ok(TryConf { conf, errors })
-                fn $config() -> $Ty {
+            }
-                    let x = $default;
-                    x
-                }
-            )+
         }
     };
 }
 
-pub use self::helpers::Conf;
+// N.B., this macro is parsed by util/lintlib.py
 define_Conf! {
-    /// Lint: CLONED_INSTEAD_OF_COPIED, REDUNDANT_FIELD_NAMES, REDUNDANT_STATIC_LIFETIMES, FILTER_MAP_NEXT, CHECKED_CONVERSIONS, MANUAL_RANGE_CONTAINS, USE_SELF, MEM_REPLACE_WITH_DEFAULT, MANUAL_NON_EXHAUSTIVE, OPTION_AS_REF_DEREF, MAP_UNWRAP_OR, MATCH_LIKE_MATCHES_MACRO, MANUAL_STRIP, MISSING_CONST_FOR_FN, UNNESTED_OR_PATTERNS, FROM_OVER_INTO, PTR_AS_PTR. The minimum rust version that the project supports
+    /// Lint: CLONED_INSTEAD_OF_COPIED, REDUNDANT_FIELD_NAMES, REDUNDANT_STATIC_LIFETIMES, FILTER_MAP_NEXT, CHECKED_CONVERSIONS, MANUAL_RANGE_CONTAINS, USE_SELF, MEM_REPLACE_WITH_DEFAULT, MANUAL_NON_EXHAUSTIVE, OPTION_AS_REF_DEREF, MAP_UNWRAP_OR, MATCH_LIKE_MATCHES_MACRO, MANUAL_STRIP, MISSING_CONST_FOR_FN, UNNESTED_OR_PATTERNS, FROM_OVER_INTO, PTR_AS_PTR, IF_THEN_SOME_ELSE_NONE. The minimum rust version that the project supports
-    (msrv, "msrv": Option<String>, None),
+    (msrv: Option<String> = None),
     /// Lint: BLACKLISTED_NAME. The list of blacklisted names to lint about. NB: `bar` is not here since it has legitimate uses
-    (blacklisted_names, "blacklisted_names": Vec<String>, ["foo", "baz", "quux"].iter().map(ToString::to_string).collect()),
+    (blacklisted_names: Vec<String> = ["foo", "baz", "quux"].iter().map(ToString::to_string).collect()),
     /// Lint: COGNITIVE_COMPLEXITY. The maximum cognitive complexity a function can have
-    (cognitive_complexity_threshold, "cognitive_complexity_threshold": u64, 25),
+    (cognitive_complexity_threshold: u64 = 25),
     /// DEPRECATED LINT: CYCLOMATIC_COMPLEXITY. Use the Cognitive Complexity lint instead.
-    (cyclomatic_complexity_threshold, "cyclomatic_complexity_threshold": Option<u64>, None),
+    #[conf_deprecated("Please use `cognitive-complexity-threshold` instead")]
+    (cyclomatic_complexity_threshold: Option<u64> = None),
     /// Lint: DOC_MARKDOWN. The list of words this lint should not consider as identifiers needing ticks
-    (doc_valid_idents, "doc_valid_idents": Vec<String>, [
+    (doc_valid_idents: Vec<String> = [
         "KiB", "MiB", "GiB", "TiB", "PiB", "EiB",
         "DirectX",
         "ECMAScript",
@@ -136,54 +125,47 @@ define_Conf! {
         "CamelCase",
     ].iter().map(ToString::to_string).collect()),
     /// Lint: TOO_MANY_ARGUMENTS. The maximum number of argument a function or method can have
-    (too_many_arguments_threshold, "too_many_arguments_threshold": u64, 7),
+    (too_many_arguments_threshold: u64 = 7),
     /// Lint: TYPE_COMPLEXITY. The maximum complexity a type can have
-    (type_complexity_threshold, "type_complexity_threshold": u64, 250),
+    (type_complexity_threshold: u64 = 250),
     /// Lint: MANY_SINGLE_CHAR_NAMES. The maximum number of single char bindings a scope may have
-    (single_char_binding_names_threshold, "single_char_binding_names_threshold": u64, 4),
+    (single_char_binding_names_threshold: u64 = 4),
     /// Lint: BOXED_LOCAL, USELESS_VEC. The maximum size of objects (in bytes) that will be linted. Larger objects are ok on the heap
-    (too_large_for_stack, "too_large_for_stack": u64, 200),
+    (too_large_for_stack: u64 = 200),
     /// Lint: ENUM_VARIANT_NAMES. The minimum number of enum variants for the lints about variant names to trigger
-    (enum_variant_name_threshold, "enum_variant_name_threshold": u64, 3),
+    (enum_variant_name_threshold: u64 = 3),
     /// Lint: LARGE_ENUM_VARIANT. The maximum size of a enum's variant to avoid box suggestion
-    (enum_variant_size_threshold, "enum_variant_size_threshold": u64, 200),
+    (enum_variant_size_threshold: u64 = 200),
     /// Lint: VERBOSE_BIT_MASK. The maximum allowed size of a bit mask before suggesting to use 'trailing_zeros'
-    (verbose_bit_mask_threshold, "verbose_bit_mask_threshold": u64, 1),
+    (verbose_bit_mask_threshold: u64 = 1),
     /// Lint: DECIMAL_LITERAL_REPRESENTATION. The lower bound for linting decimal literals
-    (literal_representation_threshold, "literal_representation_threshold": u64, 16384),
+    (literal_representation_threshold: u64 = 16384),
     /// Lint: TRIVIALLY_COPY_PASS_BY_REF. The maximum size (in bytes) to consider a `Copy` type for passing by value instead of by reference.
-    (trivial_copy_size_limit, "trivial_copy_size_limit": Option<u64>, None),
+    (trivial_copy_size_limit: Option<u64> = None),
     /// Lint: LARGE_TYPE_PASS_BY_MOVE. The minimum size (in bytes) to consider a type for passing by reference instead of by value.
-    (pass_by_value_size_limit, "pass_by_value_size_limit": u64, 256),
+    (pass_by_value_size_limit: u64 = 256),
     /// Lint: TOO_MANY_LINES. The maximum number of lines a function or method can have
-    (too_many_lines_threshold, "too_many_lines_threshold": u64, 100),
+    (too_many_lines_threshold: u64 = 100),
     /// Lint: LARGE_STACK_ARRAYS, LARGE_CONST_ARRAYS. The maximum allowed size for arrays on the stack
-    (array_size_threshold, "array_size_threshold": u64, 512_000),
+    (array_size_threshold: u64 = 512_000),
     /// Lint: VEC_BOX. The size of the boxed type in bytes, where boxing in a `Vec` is allowed
-    (vec_box_size_threshold, "vec_box_size_threshold": u64, 4096),
+    (vec_box_size_threshold: u64 = 4096),
     /// Lint: TYPE_REPETITION_IN_BOUNDS. The maximum number of bounds a trait can have to be linted
-    (max_trait_bounds, "max_trait_bounds": u64, 3),
+    (max_trait_bounds: u64 = 3),
     /// Lint: STRUCT_EXCESSIVE_BOOLS. The maximum number of bools a struct can have
-    (max_struct_bools, "max_struct_bools": u64, 3),
+    (max_struct_bools: u64 = 3),
     /// Lint: FN_PARAMS_EXCESSIVE_BOOLS. The maximum number of bools function parameters can have
-    (max_fn_params_bools, "max_fn_params_bools": u64, 3),
+    (max_fn_params_bools: u64 = 3),
     /// Lint: WILDCARD_IMPORTS. Whether to allow certain wildcard imports (prelude, super in tests).
-    (warn_on_all_wildcard_imports, "warn_on_all_wildcard_imports": bool, false),
+    (warn_on_all_wildcard_imports: bool = false),
     /// Lint: DISALLOWED_METHOD. The list of disallowed methods, written as fully qualified paths.
-    (disallowed_methods, "disallowed_methods": Vec<String>, Vec::<String>::new()),
+    (disallowed_methods: Vec<String> = Vec::new()),
     /// Lint: UNREADABLE_LITERAL. Should the fraction of a decimal be linted to include separators.
-    (unreadable_literal_lint_fractions, "unreadable_literal_lint_fractions": bool, true),
+    (unreadable_literal_lint_fractions: bool = true),
     /// Lint: UPPER_CASE_ACRONYMS. Enables verbose mode. Triggers if there is more than one uppercase char next to each other
-    (upper_case_acronyms_aggressive, "upper_case_acronyms_aggressive": bool, false),
+    (upper_case_acronyms_aggressive: bool = false),
     /// Lint: _CARGO_COMMON_METADATA. For internal testing only, ignores the current `publish` settings in the Cargo manifest.
-    (cargo_ignore_publish, "cargo_ignore_publish": bool, false),
+    (cargo_ignore_publish: bool = false),
-}
-
-impl Default for Conf {
-    #[must_use]
-    fn default() -> Self {
-        toml::from_str("").expect("we never error on empty config files")
-    }
 }
 
 /// Search for the configuration file.
@@ -217,43 +199,13 @@ pub fn lookup_conf_file() -> io::Result<Option<PathBuf>> {
     }
 }
 
-/// Produces a `Conf` filled with the default values and forwards the errors
-///
-/// Used internally for convenience
-fn default(errors: Vec<Error>) -> (Conf, Vec<Error>) {
-    (Conf::default(), errors)
-}
-
 /// Read the `toml` configuration file.
 ///
 /// In case of error, the function tries to continue as much as possible.
-pub fn read(path: &Path) -> (Conf, Vec<Error>) {
+pub fn read(path: &Path) -> TryConf {
     let content = match fs::read_to_string(path) {
+        Err(e) => return TryConf::from_error(e),
         Ok(content) => content,
-        Err(err) => return default(vec![err.into()]),
     };
-
+    toml::from_str(&content).unwrap_or_else(TryConf::from_error)
-    assert!(ERRORS.lock().expect("no threading -> mutex always safe").is_empty());
-    match toml::from_str(&content) {
-        Ok(toml) => {
-            let mut errors = ERRORS.lock().expect("no threading -> mutex always safe").split_off(0);
-
-            let toml_ref: &Conf = &toml;
-
-            let cyc_field: Option<u64> = toml_ref.cyclomatic_complexity_threshold;
-
-            if cyc_field.is_some() {
-                let cyc_err = "found deprecated field `cyclomatic-complexity-threshold`. Please use `cognitive-complexity-threshold` instead.".to_string();
-                errors.push(Error::Toml(cyc_err));
-            }
-
-            (toml, errors)
-        },
-        Err(e) => {
-            let mut errors = ERRORS.lock().expect("no threading -> mutex always safe").split_off(0);
-            errors.push(Error::Toml(e.to_string()));
-
-            default(errors)
-        },
-    }
 }

src/tools/clippy/clippy_lints/src/utils/internal_lints.rs

@@ -32,6 +32,9 @@ use rustc_typeck::hir_ty_to_ty;
 
 use std::borrow::{Borrow, Cow};
 
+#[cfg(feature = "metadata-collector-lint")]
+pub mod metadata_collector;
+
 declare_clippy_lint! {
     /// **What it does:** Checks for various things we like to keep tidy in clippy.
     ///

src/tools/clippy/clippy_lints/src/utils/internal_lints/metadata_collector.rs

@@ -0,0 +1,632 @@
+//! This lint is used to collect metadata about clippy lints. This metadata is exported as a json
+//! file and then used to generate the [clippy lint list](https://rust-lang.github.io/rust-clippy/master/index.html)
+//!
+//! This module and therefor the entire lint is guarded by a feature flag called
+//! `metadata-collector-lint`
+//!
+//! The module transforms all lint names to ascii lowercase to ensure that we don't have mismatches
+//! during any comparison or mapping. (Please take care of this, it's not fun to spend time on such
+//! a simple mistake)
+
+// # NITs
+// - TODO xFrednet 2021-02-13: Collect depreciations and maybe renames
+
+use if_chain::if_chain;
+use rustc_data_structures::fx::FxHashMap;
+use rustc_hir::{
+    self as hir, def::DefKind, intravisit, intravisit::Visitor, ExprKind, Item, ItemKind, Mutability, QPath,
+};
+use rustc_lint::{CheckLintNameResult, LateContext, LateLintPass, LintContext, LintId};
+use rustc_middle::hir::map::Map;
+use rustc_session::{declare_tool_lint, impl_lint_pass};
+use rustc_span::{sym, Loc, Span, Symbol};
+use serde::{ser::SerializeStruct, Serialize, Serializer};
+use std::collections::BinaryHeap;
+use std::fs::{self, OpenOptions};
+use std::io::prelude::*;
+use std::path::Path;
+
+use crate::utils::internal_lints::is_lint_ref_type;
+use clippy_utils::{
+    diagnostics::span_lint, last_path_segment, match_function_call, match_path, paths, ty::match_type,
+    ty::walk_ptrs_ty_depth,
+};
+
+/// This is the output file of the lint collector.
+const OUTPUT_FILE: &str = "../util/gh-pages/metadata_collection.json";
+/// These lints are excluded from the export.
+const BLACK_LISTED_LINTS: [&str; 3] = ["lint_author", "deep_code_inspection", "internal_metadata_collector"];
+/// These groups will be ignored by the lint group matcher. This is useful for collections like
+/// `clippy::all`
+const IGNORED_LINT_GROUPS: [&str; 1] = ["clippy::all"];
+/// Lints within this group will be excluded from the collection
+const EXCLUDED_LINT_GROUPS: [&str; 1] = ["clippy::internal"];
+
+const LINT_EMISSION_FUNCTIONS: [&[&str]; 7] = [
+    &["clippy_utils", "diagnostics", "span_lint"],
+    &["clippy_utils", "diagnostics", "span_lint_and_help"],
+    &["clippy_utils", "diagnostics", "span_lint_and_note"],
+    &["clippy_utils", "diagnostics", "span_lint_hir"],
+    &["clippy_utils", "diagnostics", "span_lint_and_sugg"],
+    &["clippy_utils", "diagnostics", "span_lint_and_then"],
+    &["clippy_utils", "diagnostics", "span_lint_hir_and_then"],
+];
+const SUGGESTION_DIAGNOSTIC_BUILDER_METHODS: [(&str, bool); 9] = [
+    ("span_suggestion", false),
+    ("span_suggestion_short", false),
+    ("span_suggestion_verbose", false),
+    ("span_suggestion_hidden", false),
+    ("tool_only_span_suggestion", false),
+    ("multipart_suggestion", true),
+    ("multipart_suggestions", true),
+    ("tool_only_multipart_suggestion", true),
+    ("span_suggestions", true),
+];
+const SUGGESTION_FUNCTIONS: [&[&str]; 2] = [
+    &["clippy_utils", "diagnostics", "multispan_sugg"],
+    &["clippy_utils", "diagnostics", "multispan_sugg_with_applicability"],
+];
+
+/// The index of the applicability name of `paths::APPLICABILITY_VALUES`
+const APPLICABILITY_NAME_INDEX: usize = 2;
+
+declare_clippy_lint! {
+    /// **What it does:** Collects metadata about clippy lints for the website.
+    ///
+    /// This lint will be used to report problems of syntax parsing. You should hopefully never
+    /// see this but never say never I guess ^^
+    ///
+    /// **Why is this bad?** This is not a bad thing but definitely a hacky way to do it. See
+    /// issue [#4310](https://github.com/rust-lang/rust-clippy/issues/4310) for a discussion
+    /// about the implementation.
+    ///
+    /// **Known problems:** Hopefully none. It would be pretty uncool to have a problem here :)
+    ///
+    /// **Example output:**
+    /// ```json,ignore
+    /// {
+    ///     "id": "internal_metadata_collector",
+    ///     "id_span": {
+    ///         "path": "clippy_lints/src/utils/internal_lints/metadata_collector.rs",
+    ///         "line": 1
+    ///     },
+    ///     "group": "clippy::internal",
+    ///     "docs": " **What it does:** Collects metadata about clippy lints for the website. [...] "
+    /// }
+    /// ```
+    pub INTERNAL_METADATA_COLLECTOR,
+    internal_warn,
+    "A busy bee collection metadata about lints"
+}
+
+impl_lint_pass!(MetadataCollector => [INTERNAL_METADATA_COLLECTOR]);
+
+#[allow(clippy::module_name_repetitions)]
+#[derive(Debug, Clone, Default)]
+pub struct MetadataCollector {
+    /// All collected lints
+    ///
+    /// We use a Heap here to have the lints added in alphabetic order in the export
+    lints: BinaryHeap<LintMetadata>,
+    applicability_info: FxHashMap<String, ApplicabilityInfo>,
+}
+
+impl Drop for MetadataCollector {
+    /// You might ask: How hacky is this?
+    /// My answer:     YES
+    fn drop(&mut self) {
+        // The metadata collector gets dropped twice, this makes sure that we only write
+        // when the list is full
+        if self.lints.is_empty() {
+            return;
+        }
+
+        let mut applicability_info = std::mem::take(&mut self.applicability_info);
+
+        // Mapping the final data
+        let mut lints = std::mem::take(&mut self.lints).into_sorted_vec();
+        lints
+            .iter_mut()
+            .for_each(|x| x.applicability = applicability_info.remove(&x.id));
+
+        // Outputting
+        if Path::new(OUTPUT_FILE).exists() {
+            fs::remove_file(OUTPUT_FILE).unwrap();
+        }
+        let mut file = OpenOptions::new().write(true).create(true).open(OUTPUT_FILE).unwrap();
+        writeln!(file, "{}", serde_json::to_string_pretty(&lints).unwrap()).unwrap();
+    }
+}
+
+#[derive(Debug, Clone, Serialize, PartialEq, Eq, PartialOrd, Ord)]
+struct LintMetadata {
+    id: String,
+    id_span: SerializableSpan,
+    group: String,
+    docs: String,
+    /// This field is only used in the output and will only be
+    /// mapped shortly before the actual output.
+    applicability: Option<ApplicabilityInfo>,
+}
+
+impl LintMetadata {
+    fn new(id: String, id_span: SerializableSpan, group: String, docs: String) -> Self {
+        Self {
+            id,
+            id_span,
+            group,
+            docs,
+            applicability: None,
+        }
+    }
+}
+
+#[derive(Debug, Clone, Serialize, PartialEq, Eq, PartialOrd, Ord)]
+struct SerializableSpan {
+    path: String,
+    line: usize,
+}
+
+impl std::fmt::Display for SerializableSpan {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{}:{}", self.path.rsplit('/').next().unwrap_or_default(), self.line)
+    }
+}
+
+impl SerializableSpan {
+    fn from_item(cx: &LateContext<'_>, item: &Item<'_>) -> Self {
+        Self::from_span(cx, item.ident.span)
+    }
+
+    fn from_span(cx: &LateContext<'_>, span: Span) -> Self {
+        let loc: Loc = cx.sess().source_map().lookup_char_pos(span.lo());
+
+        Self {
+            path: format!("{}", loc.file.name),
+            line: loc.line,
+        }
+    }
+}
+
+#[derive(Debug, Clone, Default, PartialEq, Eq, PartialOrd, Ord)]
+struct ApplicabilityInfo {
+    /// Indicates if any of the lint emissions uses multiple spans. This is related to
+    /// [rustfix#141](https://github.com/rust-lang/rustfix/issues/141) as such suggestions can
+    /// currently not be applied automatically.
+    is_multi_part_suggestion: bool,
+    applicability: Option<usize>,
+}
+
+impl Serialize for ApplicabilityInfo {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        let index = self.applicability.unwrap_or_default();
+
+        let mut s = serializer.serialize_struct("ApplicabilityInfo", 2)?;
+        s.serialize_field("is_multi_part_suggestion", &self.is_multi_part_suggestion)?;
+        s.serialize_field(
+            "applicability",
+            &paths::APPLICABILITY_VALUES[index][APPLICABILITY_NAME_INDEX],
+        )?;
+        s.end()
+    }
+}
+
+impl<'hir> LateLintPass<'hir> for MetadataCollector {
+    /// Collecting lint declarations like:
+    /// ```rust, ignore
+    /// declare_clippy_lint! {
+    ///     /// **What it does:** Something IDK.
+    ///     pub SOME_LINT,
+    ///     internal,
+    ///     "Who am I?"
+    /// }
+    /// ```
+    fn check_item(&mut self, cx: &LateContext<'hir>, item: &'hir Item<'_>) {
+        if_chain! {
+            // item validation
+            if let ItemKind::Static(ref ty, Mutability::Not, _) = item.kind;
+            if is_lint_ref_type(cx, ty);
+            // blacklist check
+            let lint_name = sym_to_string(item.ident.name).to_ascii_lowercase();
+            if !BLACK_LISTED_LINTS.contains(&lint_name.as_str());
+            // metadata extraction
+            if let Some(group) = get_lint_group_or_lint(cx, &lint_name, item);
+            if let Some(docs) = extract_attr_docs_or_lint(cx, item);
+            then {
+                self.lints.push(LintMetadata::new(
+                    lint_name,
+                    SerializableSpan::from_item(cx, item),
+                    group,
+                    docs,
+                ));
+            }
+        }
+    }
+
+    /// Collecting constant applicability from the actual lint emissions
+    ///
+    /// Example:
+    /// ```rust, ignore
+    /// span_lint_and_sugg(
+    ///     cx,
+    ///     SOME_LINT,
+    ///     item.span,
+    ///     "Le lint message",
+    ///     "Here comes help:",
+    ///     "#![allow(clippy::all)]",
+    ///     Applicability::MachineApplicable, // <-- Extracts this constant value
+    /// );
+    /// ```
+    fn check_expr(&mut self, cx: &LateContext<'hir>, expr: &'hir hir::Expr<'_>) {
+        if let Some(args) = match_lint_emission(cx, expr) {
+            let mut emission_info = extract_emission_info(cx, args);
+            if emission_info.is_empty() {
+                // See:
+                // - src/misc.rs:734:9
+                // - src/methods/mod.rs:3545:13
+                // - src/methods/mod.rs:3496:13
+                // We are basically unable to resolve the lint name it self.
+                return;
+            }
+
+            for (lint_name, applicability, is_multi_part) in emission_info.drain(..) {
+                let app_info = self.applicability_info.entry(lint_name).or_default();
+                app_info.applicability = applicability;
+                app_info.is_multi_part_suggestion = is_multi_part;
+            }
+        }
+    }
+}
+
+// ==================================================================
+// Lint definition extraction
+// ==================================================================
+fn sym_to_string(sym: Symbol) -> String {
+    sym.as_str().to_string()
+}
+
+fn extract_attr_docs_or_lint(cx: &LateContext<'_>, item: &Item<'_>) -> Option<String> {
+    extract_attr_docs(cx, item).or_else(|| {
+        lint_collection_error_item(cx, item, "could not collect the lint documentation");
+        None
+    })
+}
+
+/// This function collects all documentation that has been added to an item using
+/// `#[doc = r""]` attributes. Several attributes are aggravated using line breaks
+///
+/// ```ignore
+/// #[doc = r"Hello world!"]
+/// #[doc = r"=^.^="]
+/// struct SomeItem {}
+/// ```
+///
+/// Would result in `Hello world!\n=^.^=\n`
+fn extract_attr_docs(cx: &LateContext<'_>, item: &Item<'_>) -> Option<String> {
+    cx.tcx
+        .hir()
+        .attrs(item.hir_id())
+        .iter()
+        .filter_map(|ref x| x.doc_str().map(|sym| sym.as_str().to_string()))
+        .reduce(|mut acc, sym| {
+            acc.push_str(&sym);
+            acc.push('\n');
+            acc
+        })
+}
+
+fn get_lint_group_or_lint(cx: &LateContext<'_>, lint_name: &str, item: &'hir Item<'_>) -> Option<String> {
+    let result = cx.lint_store.check_lint_name(lint_name, Some(sym::clippy));
+    if let CheckLintNameResult::Tool(Ok(lint_lst)) = result {
+        get_lint_group(cx, lint_lst[0])
+            .or_else(|| {
+                lint_collection_error_item(cx, item, "Unable to determine lint group");
+                None
+            })
+            .filter(|group| !EXCLUDED_LINT_GROUPS.contains(&group.as_str()))
+    } else {
+        lint_collection_error_item(cx, item, "Unable to find lint in lint_store");
+        None
+    }
+}
+
+fn get_lint_group(cx: &LateContext<'_>, lint_id: LintId) -> Option<String> {
+    for (group_name, lints, _) in &cx.lint_store.get_lint_groups() {
+        if IGNORED_LINT_GROUPS.contains(group_name) {
+            continue;
+        }
+
+        if lints.iter().any(|x| *x == lint_id) {
+            return Some((*group_name).to_string());
+        }
+    }
+
+    None
+}
+
+// ==================================================================
+// Lint emission
+// ==================================================================
+fn lint_collection_error_item(cx: &LateContext<'_>, item: &Item<'_>, message: &str) {
+    span_lint(
+        cx,
+        INTERNAL_METADATA_COLLECTOR,
+        item.ident.span,
+        &format!("metadata collection error for `{}`: {}", item.ident.name, message),
+    );
+}
+
+// ==================================================================
+// Applicability
+// ==================================================================
+/// This function checks if a given expression is equal to a simple lint emission function call.
+/// It will return the function arguments if the emission matched any function.
+fn match_lint_emission<'hir>(cx: &LateContext<'hir>, expr: &'hir hir::Expr<'_>) -> Option<&'hir [hir::Expr<'hir>]> {
+    LINT_EMISSION_FUNCTIONS
+        .iter()
+        .find_map(|emission_fn| match_function_call(cx, expr, emission_fn))
+}
+
+fn take_higher_applicability(a: Option<usize>, b: Option<usize>) -> Option<usize> {
+    a.map_or(b, |a| a.max(b.unwrap_or_default()).into())
+}
+
+fn extract_emission_info<'hir>(
+    cx: &LateContext<'hir>,
+    args: &'hir [hir::Expr<'hir>],
+) -> Vec<(String, Option<usize>, bool)> {
+    let mut lints = Vec::new();
+    let mut applicability = None;
+    let mut multi_part = false;
+
+    for arg in args {
+        let (arg_ty, _) = walk_ptrs_ty_depth(cx.typeck_results().expr_ty(&arg));
+
+        if match_type(cx, arg_ty, &paths::LINT) {
+            // If we found the lint arg, extract the lint name
+            let mut resolved_lints = resolve_lints(cx, arg);
+            lints.append(&mut resolved_lints);
+        } else if match_type(cx, arg_ty, &paths::APPLICABILITY) {
+            applicability = resolve_applicability(cx, arg);
+        } else if arg_ty.is_closure() {
+            multi_part |= check_is_multi_part(cx, arg);
+            // TODO xFrednet 2021-03-01: don't use or_else but rather a comparison
+            applicability = applicability.or_else(|| resolve_applicability(cx, arg));
+        }
+    }
+
+    lints
+        .drain(..)
+        .map(|lint_name| (lint_name, applicability, multi_part))
+        .collect()
+}
+
+/// Resolves the possible lints that this expression could reference
+fn resolve_lints(cx: &LateContext<'hir>, expr: &'hir hir::Expr<'hir>) -> Vec<String> {
+    let mut resolver = LintResolver::new(cx);
+    resolver.visit_expr(expr);
+    resolver.lints
+}
+
+/// This function tries to resolve the linked applicability to the given expression.
+fn resolve_applicability(cx: &LateContext<'hir>, expr: &'hir hir::Expr<'hir>) -> Option<usize> {
+    let mut resolver = ApplicabilityResolver::new(cx);
+    resolver.visit_expr(expr);
+    resolver.complete()
+}
+
+fn check_is_multi_part(cx: &LateContext<'hir>, closure_expr: &'hir hir::Expr<'hir>) -> bool {
+    if let ExprKind::Closure(_, _, body_id, _, _) = closure_expr.kind {
+        let mut scanner = IsMultiSpanScanner::new(cx);
+        intravisit::walk_body(&mut scanner, cx.tcx.hir().body(body_id));
+        return scanner.is_multi_part();
+    } else if let Some(local) = get_parent_local(cx, closure_expr) {
+        if let Some(local_init) = local.init {
+            return check_is_multi_part(cx, local_init);
+        }
+    }
+
+    false
+}
+
+struct LintResolver<'a, 'hir> {
+    cx: &'a LateContext<'hir>,
+    lints: Vec<String>,
+}
+
+impl<'a, 'hir> LintResolver<'a, 'hir> {
+    fn new(cx: &'a LateContext<'hir>) -> Self {
+        Self {
+            cx,
+            lints: Vec::<String>::default(),
+        }
+    }
+}
+
+impl<'a, 'hir> intravisit::Visitor<'hir> for LintResolver<'a, 'hir> {
+    type Map = Map<'hir>;
+
+    fn nested_visit_map(&mut self) -> intravisit::NestedVisitorMap<Self::Map> {
+        intravisit::NestedVisitorMap::All(self.cx.tcx.hir())
+    }
+
+    fn visit_expr(&mut self, expr: &'hir hir::Expr<'hir>) {
+        if_chain! {
+            if let ExprKind::Path(qpath) = &expr.kind;
+            if let QPath::Resolved(_, path) = qpath;
+
+            let (expr_ty, _) = walk_ptrs_ty_depth(self.cx.typeck_results().expr_ty(&expr));
+            if match_type(self.cx, expr_ty, &paths::LINT);
+            then {
+                if let hir::def::Res::Def(DefKind::Static, _) = path.res {
+                    let lint_name = last_path_segment(qpath).ident.name;
+                    self.lints.push(sym_to_string(lint_name).to_ascii_lowercase());
+                } else if let Some(local) = get_parent_local(self.cx, expr) {
+                    if let Some(local_init) = local.init {
+                        intravisit::walk_expr(self, local_init);
+                    }
+                }
+            }
+        }
+
+        intravisit::walk_expr(self, expr);
+    }
+}
+
+/// This visitor finds the highest applicability value in the visited expressions
+struct ApplicabilityResolver<'a, 'hir> {
+    cx: &'a LateContext<'hir>,
+    /// This is the index of hightest `Applicability` for `paths::APPLICABILITY_VALUES`
+    applicability_index: Option<usize>,
+}
+
+impl<'a, 'hir> ApplicabilityResolver<'a, 'hir> {
+    fn new(cx: &'a LateContext<'hir>) -> Self {
+        Self {
+            cx,
+            applicability_index: None,
+        }
+    }
+
+    fn add_new_index(&mut self, new_index: usize) {
+        self.applicability_index = take_higher_applicability(self.applicability_index, Some(new_index));
+    }
+
+    fn complete(self) -> Option<usize> {
+        self.applicability_index
+    }
+}
+
+impl<'a, 'hir> intravisit::Visitor<'hir> for ApplicabilityResolver<'a, 'hir> {
+    type Map = Map<'hir>;
+
+    fn nested_visit_map(&mut self) -> intravisit::NestedVisitorMap<Self::Map> {
+        intravisit::NestedVisitorMap::All(self.cx.tcx.hir())
+    }
+
+    fn visit_path(&mut self, path: &'hir hir::Path<'hir>, _id: hir::HirId) {
+        for (index, enum_value) in paths::APPLICABILITY_VALUES.iter().enumerate() {
+            if match_path(path, enum_value) {
+                self.add_new_index(index);
+                return;
+            }
+        }
+    }
+
+    fn visit_expr(&mut self, expr: &'hir hir::Expr<'hir>) {
+        let (expr_ty, _) = walk_ptrs_ty_depth(self.cx.typeck_results().expr_ty(&expr));
+
+        if_chain! {
+            if match_type(self.cx, expr_ty, &paths::APPLICABILITY);
+            if let Some(local) = get_parent_local(self.cx, expr);
+            if let Some(local_init) = local.init;
+            then {
+                intravisit::walk_expr(self, local_init);
+            }
+        };
+
+        // TODO xFrednet 2021-03-01: support function arguments?
+
+        intravisit::walk_expr(self, expr);
+    }
+}
+
+/// This returns the parent local node if the expression is a reference one
+fn get_parent_local(cx: &LateContext<'hir>, expr: &'hir hir::Expr<'hir>) -> Option<&'hir hir::Local<'hir>> {
+    if let ExprKind::Path(QPath::Resolved(_, path)) = expr.kind {
+        if let hir::def::Res::Local(local_hir) = path.res {
+            return get_parent_local_hir_id(cx, local_hir);
+        }
+    }
+
+    None
+}
+
+fn get_parent_local_hir_id(cx: &LateContext<'hir>, hir_id: hir::HirId) -> Option<&'hir hir::Local<'hir>> {
+    let map = cx.tcx.hir();
+
+    match map.find(map.get_parent_node(hir_id)) {
+        Some(hir::Node::Local(local)) => Some(local),
+        Some(hir::Node::Pat(pattern)) => get_parent_local_hir_id(cx, pattern.hir_id),
+        _ => None,
+    }
+}
+
+/// This visitor finds the highest applicability value in the visited expressions
+struct IsMultiSpanScanner<'a, 'hir> {
+    cx: &'a LateContext<'hir>,
+    suggestion_count: usize,
+}
+
+impl<'a, 'hir> IsMultiSpanScanner<'a, 'hir> {
+    fn new(cx: &'a LateContext<'hir>) -> Self {
+        Self {
+            cx,
+            suggestion_count: 0,
+        }
+    }
+
+    /// Add a new single expression suggestion to the counter
+    fn add_single_span_suggestion(&mut self) {
+        self.suggestion_count += 1;
+    }
+
+    /// Signals that a suggestion with possible multiple spans was found
+    fn add_multi_part_suggestion(&mut self) {
+        self.suggestion_count += 2;
+    }
+
+    /// Checks if the suggestions include multiple spanns
+    fn is_multi_part(&self) -> bool {
+        self.suggestion_count > 1
+    }
+}
+
+impl<'a, 'hir> intravisit::Visitor<'hir> for IsMultiSpanScanner<'a, 'hir> {
+    type Map = Map<'hir>;
+
+    fn nested_visit_map(&mut self) -> intravisit::NestedVisitorMap<Self::Map> {
+        intravisit::NestedVisitorMap::All(self.cx.tcx.hir())
+    }
+
+    fn visit_expr(&mut self, expr: &'hir hir::Expr<'hir>) {
+        // Early return if the lint is already multi span
+        if self.is_multi_part() {
+            return;
+        }
+
+        match &expr.kind {
+            ExprKind::Call(fn_expr, _args) => {
+                let found_function = SUGGESTION_FUNCTIONS
+                    .iter()
+                    .any(|func_path| match_function_call(self.cx, fn_expr, func_path).is_some());
+                if found_function {
+                    // These functions are all multi part suggestions
+                    self.add_single_span_suggestion()
+                }
+            },
+            ExprKind::MethodCall(path, _path_span, arg, _arg_span) => {
+                let (self_ty, _) = walk_ptrs_ty_depth(self.cx.typeck_results().expr_ty(&arg[0]));
+                if match_type(self.cx, self_ty, &paths::DIAGNOSTIC_BUILDER) {
+                    let called_method = path.ident.name.as_str().to_string();
+                    for (method_name, is_multi_part) in &SUGGESTION_DIAGNOSTIC_BUILDER_METHODS {
+                        if *method_name == called_method {
+                            if *is_multi_part {
+                                self.add_multi_part_suggestion();
+                            } else {
+                                self.add_single_span_suggestion();
+                            }
+                            break;
+                        }
+                    }
+                }
+            },
+            _ => {},
+        }
+
+        intravisit::walk_expr(self, expr);
+    }
+}

src/tools/clippy/clippy_lints/src/utils/mod.rs

@@ -1,5 +1,5 @@
 pub mod author;
 pub mod conf;
 pub mod inspector;
-#[cfg(feature = "internal-lints")]
+#[cfg(any(feature = "internal-lints", feature = "metadata-collector-lint"))]
 pub mod internal_lints;

src/tools/clippy/clippy_utils/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "clippy_utils"
-version = "0.1.53"
+version = "0.1.54"
 authors = ["The Rust Clippy Developers"]
 edition = "2018"
 publish = false
@@ -15,6 +15,7 @@ rustc-semver="1.1.0"
 
 [features]
 internal-lints = []
+metadata-collector-lint = []
 
 [package.metadata.rust-analyzer]
 # This crate uses #[feature(rustc_private)]

src/tools/clippy/clippy_utils/src/diagnostics.rs

@@ -1,4 +1,12 @@
 //! Clippy wrappers around rustc's diagnostic functions.
+//!
+//! These functions are used by the `INTERNAL_METADATA_COLLECTOR` lint to collect the corresponding
+//! lint applicability. Please make sure that you update the `LINT_EMISSION_FUNCTIONS` variable in
+//! `clippy_lints::utils::internal_lints::metadata_collector` when a new function is added
+//! or renamed.
+//!
+//! Thank you!
+//! ~The `INTERNAL_METADATA_COLLECTOR` lint
 
 use rustc_errors::{Applicability, DiagnosticBuilder};
 use rustc_hir::HirId;

src/tools/clippy/clippy_utils/src/hir_utils.rs

@@ -713,7 +713,7 @@ impl<'a, 'tcx> SpanlessHash<'a, 'tcx> {
                 self.hash_expr(e);
 
                 for arm in arms {
-                    // TODO: arm.pat?
+                    self.hash_pat(arm.pat);
                     if let Some(ref e) = arm.guard {
                         self.hash_guard(e);
                     }
@@ -791,6 +791,72 @@ impl<'a, 'tcx> SpanlessHash<'a, 'tcx> {
         // self.maybe_typeck_results.unwrap().qpath_res(p, id).hash(&mut self.s);
     }
 
+    pub fn hash_pat(&mut self, pat: &Pat<'_>) {
+        std::mem::discriminant(&pat.kind).hash(&mut self.s);
+        match pat.kind {
+            PatKind::Binding(ann, _, _, pat) => {
+                ann.hash_stable(&mut self.cx.tcx.get_stable_hashing_context(), &mut self.s);
+                if let Some(pat) = pat {
+                    self.hash_pat(pat);
+                }
+            },
+            PatKind::Box(pat) => self.hash_pat(pat),
+            PatKind::Lit(expr) => self.hash_expr(expr),
+            PatKind::Or(pats) => {
+                for pat in pats {
+                    self.hash_pat(pat);
+                }
+            },
+            PatKind::Path(ref qpath) => self.hash_qpath(qpath),
+            PatKind::Range(s, e, i) => {
+                if let Some(s) = s {
+                    self.hash_expr(s);
+                }
+                if let Some(e) = e {
+                    self.hash_expr(e);
+                }
+                i.hash_stable(&mut self.cx.tcx.get_stable_hashing_context(), &mut self.s);
+            },
+            PatKind::Ref(pat, m) => {
+                self.hash_pat(pat);
+                m.hash(&mut self.s);
+            },
+            PatKind::Slice(l, m, r) => {
+                for pat in l {
+                    self.hash_pat(pat);
+                }
+                if let Some(pat) = m {
+                    self.hash_pat(pat);
+                }
+                for pat in r {
+                    self.hash_pat(pat);
+                }
+            },
+            PatKind::Struct(ref qpath, fields, e) => {
+                self.hash_qpath(qpath);
+                for f in fields {
+                    self.hash_name(f.ident.name);
+                    self.hash_pat(f.pat);
+                }
+                e.hash(&mut self.s)
+            },
+            PatKind::Tuple(pats, e) => {
+                for pat in pats {
+                    self.hash_pat(pat);
+                }
+                e.hash(&mut self.s);
+            },
+            PatKind::TupleStruct(ref qpath, pats, e) => {
+                self.hash_qpath(qpath);
+                for pat in pats {
+                    self.hash_pat(pat);
+                }
+                e.hash(&mut self.s);
+            },
+            PatKind::Wild => {},
+        }
+    }
+
     pub fn hash_path(&mut self, path: &Path<'_>) {
         match path.res {
             // constant hash since equality is dependant on inter-expression context
@@ -808,6 +874,7 @@ impl<'a, 'tcx> SpanlessHash<'a, 'tcx> {
 
         match &b.kind {
             StmtKind::Local(local) => {
+                self.hash_pat(local.pat);
                 if let Some(ref init) = local.init {
                     self.hash_expr(init);
                 }
@@ -827,7 +894,7 @@ impl<'a, 'tcx> SpanlessHash<'a, 'tcx> {
         }
     }
 
-    pub fn hash_lifetime(&mut self, lifetime: &Lifetime) {
+    pub fn hash_lifetime(&mut self, lifetime: Lifetime) {
         std::mem::discriminant(&lifetime.name).hash(&mut self.s);
         if let LifetimeName::Param(ref name) = lifetime.name {
             std::mem::discriminant(name).hash(&mut self.s);
@@ -844,12 +911,8 @@ impl<'a, 'tcx> SpanlessHash<'a, 'tcx> {
     }
 
     pub fn hash_ty(&mut self, ty: &Ty<'_>) {
-        self.hash_tykind(&ty.kind);
+        std::mem::discriminant(&ty.kind).hash(&mut self.s);
-    }
+        match ty.kind {
-
-    pub fn hash_tykind(&mut self, ty: &TyKind<'_>) {
-        std::mem::discriminant(ty).hash(&mut self.s);
-        match ty {
             TyKind::Slice(ty) => {
                 self.hash_ty(ty);
             },
@@ -857,11 +920,11 @@ impl<'a, 'tcx> SpanlessHash<'a, 'tcx> {
                 self.hash_ty(ty);
                 self.hash_body(anon_const.body);
             },
-            TyKind::Ptr(mut_ty) => {
+            TyKind::Ptr(ref mut_ty) => {
                 self.hash_ty(&mut_ty.ty);
                 mut_ty.mutbl.hash(&mut self.s);
             },
-            TyKind::Rptr(lifetime, mut_ty) => {
+            TyKind::Rptr(lifetime, ref mut_ty) => {
                 self.hash_lifetime(lifetime);
                 self.hash_ty(&mut_ty.ty);
                 mut_ty.mutbl.hash(&mut self.s);
@@ -883,11 +946,11 @@ impl<'a, 'tcx> SpanlessHash<'a, 'tcx> {
                 bfn.decl.c_variadic.hash(&mut self.s);
             },
             TyKind::Tup(ty_list) => {
-                for ty in *ty_list {
+                for ty in ty_list {
                     self.hash_ty(ty);
                 }
             },
-            TyKind::Path(qpath) => match qpath {
+            TyKind::Path(ref qpath) => match qpath {
                 QPath::Resolved(ref maybe_ty, ref path) => {
                     if let Some(ref ty) = maybe_ty {
                         self.hash_ty(ty);
@@ -927,9 +990,9 @@ impl<'a, 'tcx> SpanlessHash<'a, 'tcx> {
 
     fn hash_generic_args(&mut self, arg_list: &[GenericArg<'_>]) {
         for arg in arg_list {
-            match arg {
+            match *arg {
-                GenericArg::Lifetime(ref l) => self.hash_lifetime(l),
+                GenericArg::Lifetime(l) => self.hash_lifetime(l),
-                GenericArg::Type(ref ty) => self.hash_ty(&ty),
+                GenericArg::Type(ref ty) => self.hash_ty(ty),
                 GenericArg::Const(ref ca) => self.hash_body(ca.value.body),
             }
         }

src/tools/clippy/clippy_utils/src/lib.rs

@@ -61,12 +61,12 @@ use rustc_data_structures::fx::FxHashMap;
 use rustc_hir as hir;
 use rustc_hir::def::{DefKind, Res};
 use rustc_hir::def_id::{DefId, LOCAL_CRATE};
-use rustc_hir::intravisit::{self, walk_expr, ErasedMap, NestedVisitorMap, Visitor};
+use rustc_hir::intravisit::{self, walk_expr, ErasedMap, FnKind, NestedVisitorMap, Visitor};
 use rustc_hir::LangItem::{ResultErr, ResultOk};
 use rustc_hir::{
     def, Arm, BindingAnnotation, Block, Body, Constness, Destination, Expr, ExprKind, FnDecl, GenericArgs, HirId, Impl,
-    ImplItem, ImplItemKind, Item, ItemKind, LangItem, Local, MatchSource, Node, Param, Pat, PatKind, Path, PathSegment,
+    ImplItem, ImplItemKind, IsAsync, Item, ItemKind, LangItem, Local, MatchSource, Node, Param, Pat, PatKind, Path,
-    QPath, Stmt, StmtKind, TraitItem, TraitItemKind, TraitRef, TyKind,
+    PathSegment, QPath, Stmt, StmtKind, TraitItem, TraitItemKind, TraitRef, TyKind,
 };
 use rustc_lint::{LateContext, Level, Lint, LintContext};
 use rustc_middle::hir::exports::Export;
@@ -821,7 +821,13 @@ pub fn get_parent_node(tcx: TyCtxt<'_>, id: HirId) -> Option<Node<'_>> {
 
 /// Gets the parent expression, if any –- this is useful to constrain a lint.
 pub fn get_parent_expr<'tcx>(cx: &LateContext<'tcx>, e: &Expr<'_>) -> Option<&'tcx Expr<'tcx>> {
-    match get_parent_node(cx.tcx, e.hir_id) {
+    get_parent_expr_for_hir(cx, e.hir_id)
+}
+
+/// This retrieves the parent for the given `HirId` if it's an expression. This is useful for
+/// constraint lints
+pub fn get_parent_expr_for_hir<'tcx>(cx: &LateContext<'tcx>, hir_id: hir::HirId) -> Option<&'tcx Expr<'tcx>> {
+    match get_parent_node(cx.tcx, hir_id) {
         Some(Node::Expr(parent)) => Some(parent),
         _ => None,
     }
@@ -1301,6 +1307,40 @@ pub fn if_sequence<'tcx>(mut expr: &'tcx Expr<'tcx>) -> (Vec<&'tcx Expr<'tcx>>,
     (conds, blocks)
 }
 
+/// Checks if the given function kind is an async function.
+pub fn is_async_fn(kind: FnKind<'_>) -> bool {
+    matches!(kind, FnKind::ItemFn(_, _, header, _) if header.asyncness == IsAsync::Async)
+}
+
+/// Peels away all the compiler generated code surrounding the body of an async function,
+pub fn get_async_fn_body(tcx: TyCtxt<'tcx>, body: &Body<'_>) -> Option<&'tcx Expr<'tcx>> {
+    if let ExprKind::Call(
+        _,
+        &[Expr {
+            kind: ExprKind::Closure(_, _, body, _, _),
+            ..
+        }],
+    ) = body.value.kind
+    {
+        if let ExprKind::Block(
+            Block {
+                stmts: [],
+                expr:
+                    Some(Expr {
+                        kind: ExprKind::DropTemps(expr),
+                        ..
+                    }),
+                ..
+            },
+            _,
+        ) = tcx.hir().body(body).value.kind
+        {
+            return Some(expr);
+        }
+    };
+    None
+}
+
 // Finds the `#[must_use]` attribute, if any
 pub fn must_use_attr(attrs: &[Attribute]) -> Option<&Attribute> {
     attrs.iter().find(|a| a.has_name(sym::must_use))

src/tools/clippy/clippy_utils/src/paths.rs

@@ -5,6 +5,17 @@
 //! See <https://github.com/rust-lang/rust-clippy/issues/5393> for more information.
 
 pub const ANY_TRAIT: [&str; 3] = ["core", "any", "Any"];
+#[cfg(feature = "metadata-collector-lint")]
+pub const APPLICABILITY: [&str; 2] = ["rustc_lint_defs", "Applicability"];
+#[cfg(feature = "metadata-collector-lint")]
+pub const APPLICABILITY_VALUES: [[&str; 3]; 4] = [
+    ["rustc_lint_defs", "Applicability", "Unspecified"],
+    ["rustc_lint_defs", "Applicability", "HasPlaceholders"],
+    ["rustc_lint_defs", "Applicability", "MaybeIncorrect"],
+    ["rustc_lint_defs", "Applicability", "MachineApplicable"],
+];
+#[cfg(feature = "metadata-collector-lint")]
+pub const DIAGNOSTIC_BUILDER: [&str; 3] = ["rustc_errors", "diagnostic_builder", "DiagnosticBuilder"];
 pub const ARC_PTR_EQ: [&str; 4] = ["alloc", "sync", "Arc", "ptr_eq"];
 pub const ASMUT_TRAIT: [&str; 3] = ["core", "convert", "AsMut"];
 pub const ASREF_TRAIT: [&str; 3] = ["core", "convert", "AsRef"];
@@ -72,7 +83,7 @@ pub const KW_MODULE: [&str; 3] = ["rustc_span", "symbol", "kw"];
 #[cfg(feature = "internal-lints")]
 pub const LATE_CONTEXT: [&str; 2] = ["rustc_lint", "LateContext"];
 pub const LINKED_LIST: [&str; 4] = ["alloc", "collections", "linked_list", "LinkedList"];
-#[cfg(feature = "internal-lints")]
+#[cfg(any(feature = "internal-lints", feature = "metadata-collector-lint"))]
 pub const LINT: [&str; 2] = ["rustc_lint_defs", "Lint"];
 pub const MEM_DISCRIMINANT: [&str; 3] = ["core", "mem", "discriminant"];
 pub const MEM_FORGET: [&str; 3] = ["core", "mem", "forget"];

src/tools/clippy/clippy_utils/src/source.rs

@@ -280,17 +280,17 @@ pub fn snippet_with_context(
     default: &'a str,
     applicability: &mut Applicability,
 ) -> (Cow<'a, str>, bool) {
-    let outer_span = hygiene::walk_chain(span, outer);
+    let (span, is_macro_call) = walk_span_to_context(span, outer).map_or_else(
-    let (span, is_macro_call) = if outer_span.ctxt() == outer {
+        || {
-        (outer_span, span.ctxt() != outer)
+            // The span is from a macro argument, and the outer context is the macro using the argument
-    } else {
+            if *applicability != Applicability::Unspecified {
-        // The span is from a macro argument, and the outer context is the macro using the argument
+                *applicability = Applicability::MaybeIncorrect;
-        if *applicability != Applicability::Unspecified {
+            }
-            *applicability = Applicability::MaybeIncorrect;
+            // TODO: get the argument span.
-        }
+            (span, false)
-        // TODO: get the argument span.
+        },
-        (span, false)
+        |outer_span| (outer_span, span.ctxt() != outer),
-    };
+    );
 
     (
         snippet_with_applicability(cx, span, default, applicability),
@@ -298,6 +298,37 @@ pub fn snippet_with_context(
     )
 }
 
+/// Walks the span up to the target context, thereby returning the macro call site if the span is
+/// inside a macro expansion, or the original span if it is not. Note this will return `None` in the
+/// case of the span being in a macro expansion, but the target context is from expanding a macro
+/// argument.
+///
+/// Given the following
+///
+/// ```rust,ignore
+/// macro_rules! m { ($e:expr) => { f($e) }; }
+/// g(m!(0))
+/// ```
+///
+/// If called with a span of the call to `f` and a context of the call to `g` this will return a
+/// span containing `m!(0)`. However, if called with a span of the literal `0` this will give a span
+/// containing `0` as the context is the same as the outer context.
+///
+/// This will traverse through multiple macro calls. Given the following:
+///
+/// ```rust,ignore
+/// macro_rules! m { ($e:expr) => { n!($e, 0) }; }
+/// macro_rules! n { ($e:expr, $f:expr) => { f($e, $f) }; }
+/// g(m!(0))
+/// ```
+///
+/// If called with a span of the call to `f` and a context of the call to `g` this will return a
+/// span containing `m!(0)`.
+pub fn walk_span_to_context(span: Span, outer: SyntaxContext) -> Option<Span> {
+    let outer_span = hygiene::walk_chain(span, outer);
+    (outer_span.ctxt() == outer).then(|| outer_span)
+}
+
 /// Removes block comments from the given `Vec` of lines.
 ///
 /// # Examples

src/tools/clippy/clippy_utils/src/visitors.rs

@@ -1,7 +1,7 @@
 use crate::path_to_local_id;
 use rustc_hir as hir;
-use rustc_hir::intravisit::{self, walk_expr, NestedVisitorMap, Visitor};
+use rustc_hir::intravisit::{self, walk_expr, ErasedMap, NestedVisitorMap, Visitor};
-use rustc_hir::{Arm, Body, Expr, HirId, Stmt};
+use rustc_hir::{Arm, Block, Body, Destination, Expr, ExprKind, HirId, Stmt};
 use rustc_lint::LateContext;
 use rustc_middle::hir::map::Map;
 
@@ -188,3 +188,54 @@ impl<'v> Visitor<'v> for LocalUsedVisitor<'v> {
         NestedVisitorMap::OnlyBodies(self.hir)
     }
 }
+
+pub trait Visitable<'tcx> {
+    fn visit<V: Visitor<'tcx>>(self, v: &mut V);
+}
+impl Visitable<'tcx> for &'tcx Expr<'tcx> {
+    fn visit<V: Visitor<'tcx>>(self, v: &mut V) {
+        v.visit_expr(self)
+    }
+}
+impl Visitable<'tcx> for &'tcx Block<'tcx> {
+    fn visit<V: Visitor<'tcx>>(self, v: &mut V) {
+        v.visit_block(self)
+    }
+}
+impl<'tcx> Visitable<'tcx> for &'tcx Stmt<'tcx> {
+    fn visit<V: Visitor<'tcx>>(self, v: &mut V) {
+        v.visit_stmt(self)
+    }
+}
+impl<'tcx> Visitable<'tcx> for &'tcx Body<'tcx> {
+    fn visit<V: Visitor<'tcx>>(self, v: &mut V) {
+        v.visit_body(self)
+    }
+}
+impl<'tcx> Visitable<'tcx> for &'tcx Arm<'tcx> {
+    fn visit<V: Visitor<'tcx>>(self, v: &mut V) {
+        v.visit_arm(self)
+    }
+}
+
+pub fn visit_break_exprs<'tcx>(
+    node: impl Visitable<'tcx>,
+    f: impl FnMut(&'tcx Expr<'tcx>, Destination, Option<&'tcx Expr<'tcx>>),
+) {
+    struct V<F>(F);
+    impl<'tcx, F: FnMut(&'tcx Expr<'tcx>, Destination, Option<&'tcx Expr<'tcx>>)> Visitor<'tcx> for V<F> {
+        type Map = ErasedMap<'tcx>;
+        fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
+            NestedVisitorMap::None
+        }
+
+        fn visit_expr(&mut self, e: &'tcx Expr<'_>) {
+            if let ExprKind::Break(dest, sub_expr) = e.kind {
+                self.0(e, dest, sub_expr)
+            }
+            walk_expr(self, e);
+        }
+    }
+
+    node.visit(&mut V(f));
+}

src/tools/clippy/doc/adding_lints.md

@@ -454,7 +454,7 @@ in `clippy_lints/src/utils/conf.rs`:
 ```rust
 define_Conf! {
     /// Lint: LIST, OF, LINTS, <THE_NEWLY_ADDED_LINT>. The minimum rust version that the project supports
-    (msrv, "msrv": Option<String>, None),
+    (msrv: Option<String> = None),
     ...
 }
 ```
@@ -562,7 +562,7 @@ in the following steps:
     like this:
     ```rust
     /// Lint: LINT_NAME. <The configuration field doc comment>
-    (configuration_ident, "configuration_value": Type, DefaultValue),
+    (configuration_ident: Type = DefaultValue),
     ```
     The configuration value and identifier should usually be the same. The doc comment will be
     automatically added to the lint documentation.

src/tools/clippy/rust-toolchain

@@ -1,3 +1,3 @@
 [toolchain]
-channel = "nightly-2021-04-22"
+channel = "nightly-2021-05-06"
 components = ["llvm-tools-preview", "rustc-dev", "rust-src"]

src/tools/clippy/src/driver.rs

@@ -106,7 +106,7 @@ impl rustc_driver::Callbacks for ClippyCallbacks {
                 (previous)(sess, lint_store);
             }
 
-            let conf = clippy_lints::read_conf(&[], sess);
+            let conf = clippy_lints::read_conf(sess);
             clippy_lints::register_plugins(lint_store, sess, &conf);
             clippy_lints::register_pre_expansion_lints(lint_store);
             clippy_lints::register_renamed(lint_store);

src/tools/clippy/tests/dogfood.rs

@@ -1,3 +1,8 @@
+//! This test is a part of quality control and makes clippy eat what it produces. Awesome lints and
+//! long error messages
+//!
+//! See [Eating your own dog food](https://en.wikipedia.org/wiki/Eating_your_own_dog_food) for context
+
 // Dogfood cannot run on Windows
 #![cfg(not(windows))]
 #![feature(once_cell)]
@@ -17,12 +22,14 @@ fn dogfood_clippy() {
         return;
     }
     let root_dir = PathBuf::from(env!("CARGO_MANIFEST_DIR"));
+    let enable_metadata_collection = std::env::var("ENABLE_METADATA_COLLECTION").unwrap_or_else(|_| "0".to_string());
 
     let mut command = Command::new(&*CLIPPY_PATH);
     command
         .current_dir(root_dir)
         .env("CLIPPY_DOGFOOD", "1")
         .env("CARGO_INCREMENTAL", "0")
+        .env("ENABLE_METADATA_COLLECTION", &enable_metadata_collection)
         .arg("clippy")
         .arg("--all-targets")
         .arg("--all-features")

src/tools/clippy/tests/ui-toml/bad_toml_type/conf_bad_type.stderr

@@ -1,4 +1,4 @@
-error: error reading Clippy's configuration file `$DIR/clippy.toml`: invalid type: integer `42`, expected a sequence
+error: error reading Clippy's configuration file `$DIR/clippy.toml`: invalid type: integer `42`, expected a sequence for key `blacklisted-names`
 
 error: aborting due to previous error
 

src/tools/clippy/tests/ui-toml/conf_deprecated_key/conf_deprecated_key.stderr

@@ -1,4 +1,4 @@
-error: error reading Clippy's configuration file `$DIR/clippy.toml`: found deprecated field `cyclomatic-complexity-threshold`. Please use `cognitive-complexity-threshold` instead.
+error: error reading Clippy's configuration file `$DIR/clippy.toml`: deprecated field `cyclomatic-complexity-threshold`. Please use `cognitive-complexity-threshold` instead
 
 error: aborting due to previous error
 

src/tools/clippy/tests/ui/builtin_type_shadow.stderr

@@ -1,5 +1,5 @@
 error: this generic shadows the built-in type `u32`
-  --> $DIR/builtin-type-shadow.rs:4:8
+  --> $DIR/builtin_type_shadow.rs:4:8
    |
 LL | fn foo<u32>(a: u32) -> u32 {
    |        ^^^
@@ -7,7 +7,7 @@ LL | fn foo<u32>(a: u32) -> u32 {
    = note: `-D clippy::builtin-type-shadow` implied by `-D warnings`
 
 error[E0308]: mismatched types
-  --> $DIR/builtin-type-shadow.rs:5:5
+  --> $DIR/builtin_type_shadow.rs:5:5
    |
 LL | fn foo<u32>(a: u32) -> u32 {
    |        ---             --- expected `u32` because of return type

src/tools/clippy/tests/ui/comparison_chain.rs

@@ -203,4 +203,32 @@ mod issue_5212 {
     }
 }
 
+enum Sign {
+    Negative,
+    Positive,
+    Zero,
+}
+
+impl Sign {
+    const fn sign_i8(n: i8) -> Self {
+        if n == 0 {
+            Sign::Zero
+        } else if n > 0 {
+            Sign::Positive
+        } else {
+            Sign::Negative
+        }
+    }
+}
+
+const fn sign_i8(n: i8) -> Sign {
+    if n == 0 {
+        Sign::Zero
+    } else if n > 0 {
+        Sign::Positive
+    } else {
+        Sign::Negative
+    }
+}
+
 fn main() {}

src/tools/clippy/tests/ui/copy_iterator.rs

@@ -16,8 +16,6 @@ impl Iterator for Countdown {
 
 fn main() {
     let my_iterator = Countdown(5);
-    let a: Vec<_> = my_iterator.take(1).collect();
+    assert_eq!(my_iterator.take(1).count(), 1);
-    assert_eq!(a.len(), 1);
+    assert_eq!(my_iterator.count(), 5);
-    let b: Vec<_> = my_iterator.collect();
-    assert_eq!(b.len(), 5);
 }

src/tools/clippy/tests/ui/crashes/ice-7169.rs

@@ -0,0 +1,9 @@
+#[derive(Default)]
+struct A<T> {
+    a: Vec<A<T>>,
+    b: T,
+}
+
+fn main() {
+    if let Ok(_) = Ok::<_, ()>(A::<String>::default()) {}
+}

src/tools/clippy/tests/ui/crashes/ice-7169.stderr

@@ -0,0 +1,10 @@
+error: redundant pattern matching, consider using `is_ok()`
+  --> $DIR/ice-7169.rs:8:12
+   |
+LL |     if let Ok(_) = Ok::<_, ()>(A::<String>::default()) {}
+   |     -------^^^^^-------------------------------------- help: try this: `if Ok::<_, ()>(A::<String>::default()).is_ok()`
+   |
+   = note: `-D clippy::redundant-pattern-matching` implied by `-D warnings`
+
+error: aborting due to previous error
+

src/tools/clippy/tests/ui/eval_order_dependence.rs

@@ -1,3 +1,5 @@
+// edition:2018
+
 #[warn(clippy::eval_order_dependence)]
 #[allow(
     unused_assignments,
@@ -107,3 +109,7 @@ fn main() {
         },
     );
 }
+
+async fn issue_6925() {
+    let _ = vec![async { true }.await, async { false }.await];
+}

src/tools/clippy/tests/ui/eval_order_dependence.stderr

@@ -1,48 +1,48 @@
-error: unsequenced read of a variable
+error: unsequenced read of `x`
-  --> $DIR/eval_order_dependence.rs:15:9
+  --> $DIR/eval_order_dependence.rs:17:9
    |
 LL |     } + x;
    |         ^
    |
    = note: `-D clippy::eval-order-dependence` implied by `-D warnings`
 note: whether read occurs before this write depends on evaluation order
-  --> $DIR/eval_order_dependence.rs:13:9
+  --> $DIR/eval_order_dependence.rs:15:9
    |
 LL |         x = 1;
    |         ^^^^^
 
-error: unsequenced read of a variable
+error: unsequenced read of `x`
-  --> $DIR/eval_order_dependence.rs:18:5
+  --> $DIR/eval_order_dependence.rs:20:5
    |
 LL |     x += {
    |     ^
    |
 note: whether read occurs before this write depends on evaluation order
-  --> $DIR/eval_order_dependence.rs:19:9
+  --> $DIR/eval_order_dependence.rs:21:9
    |
 LL |         x = 20;
    |         ^^^^^^
 
-error: unsequenced read of a variable
+error: unsequenced read of `x`
-  --> $DIR/eval_order_dependence.rs:31:12
+  --> $DIR/eval_order_dependence.rs:33:12
    |
 LL |         a: x,
    |            ^
    |
 note: whether read occurs before this write depends on evaluation order
-  --> $DIR/eval_order_dependence.rs:33:13
+  --> $DIR/eval_order_dependence.rs:35:13
    |
 LL |             x = 6;
    |             ^^^^^
 
-error: unsequenced read of a variable
+error: unsequenced read of `x`
-  --> $DIR/eval_order_dependence.rs:40:9
+  --> $DIR/eval_order_dependence.rs:42:9
    |
 LL |         x += {
    |         ^
    |
 note: whether read occurs before this write depends on evaluation order
-  --> $DIR/eval_order_dependence.rs:41:13
+  --> $DIR/eval_order_dependence.rs:43:13
    |
 LL |             x = 20;
    |             ^^^^^^

src/tools/clippy/tests/ui/implicit_return.fixed

@@ -1,7 +1,8 @@
+// edition:2018
 // run-rustfix
 
 #![warn(clippy::implicit_return)]
-#![allow(clippy::needless_return, unused)]
+#![allow(clippy::needless_return, clippy::needless_bool, unused, clippy::never_loop)]
 
 fn test_end_of_fn() -> bool {
     if true {
@@ -12,7 +13,6 @@ fn test_end_of_fn() -> bool {
     return true
 }
 
-#[allow(clippy::needless_bool)]
 fn test_if_block() -> bool {
     if true { return true } else { return false }
 }
@@ -25,7 +25,6 @@ fn test_match(x: bool) -> bool {
     }
 }
 
-#[allow(clippy::needless_return)]
 fn test_match_with_unreachable(x: bool) -> bool {
     match x {
         true => return false,
@@ -33,14 +32,12 @@ fn test_match_with_unreachable(x: bool) -> bool {
     }
 }
 
-#[allow(clippy::never_loop)]
 fn test_loop() -> bool {
     loop {
         return true;
     }
 }
 
-#[allow(clippy::never_loop)]
 fn test_loop_with_block() -> bool {
     loop {
         {
@@ -49,7 +46,6 @@ fn test_loop_with_block() -> bool {
     }
 }
 
-#[allow(clippy::never_loop)]
 fn test_loop_with_nests() -> bool {
     loop {
         if true {
@@ -83,15 +79,53 @@ fn test_return_macro() -> String {
     return format!("test {}", "test")
 }
 
-fn main() {
+fn macro_branch_test() -> bool {
-    let _ = test_end_of_fn();
+    macro_rules! m {
-    let _ = test_if_block();
+        ($t:expr, $f:expr) => {
-    let _ = test_match(true);
+            if true { $t } else { $f }
-    let _ = test_match_with_unreachable(true);
+        };
-    let _ = test_loop();
+    }
-    let _ = test_loop_with_block();
+    return m!(true, false)
-    let _ = test_loop_with_nests();
-    let _ = test_loop_with_if_let();
-    test_closure();
-    let _ = test_return_macro();
 }
+
+fn loop_test() -> bool {
+    'outer: loop {
+        if true {
+            return true;
+        }
+
+        let _ = loop {
+            if false {
+                return false;
+            }
+            if true {
+                break true;
+            }
+        };
+    }
+}
+
+fn loop_macro_test() -> bool {
+    macro_rules! m {
+        ($e:expr) => {
+            break $e
+        };
+    }
+    return loop {
+        m!(true);
+    }
+}
+
+fn divergent_test() -> bool {
+    fn diverge() -> ! {
+        panic!()
+    }
+    diverge()
+}
+
+// issue #6940
+async fn foo() -> bool {
+    return true
+}
+
+fn main() {}

src/tools/clippy/tests/ui/implicit_return.rs

@@ -1,7 +1,8 @@
+// edition:2018
 // run-rustfix
 
 #![warn(clippy::implicit_return)]
-#![allow(clippy::needless_return, unused)]
+#![allow(clippy::needless_return, clippy::needless_bool, unused, clippy::never_loop)]
 
 fn test_end_of_fn() -> bool {
     if true {
@@ -12,7 +13,6 @@ fn test_end_of_fn() -> bool {
     true
 }
 
-#[allow(clippy::needless_bool)]
 fn test_if_block() -> bool {
     if true { true } else { false }
 }
@@ -25,7 +25,6 @@ fn test_match(x: bool) -> bool {
     }
 }
 
-#[allow(clippy::needless_return)]
 fn test_match_with_unreachable(x: bool) -> bool {
     match x {
         true => return false,
@@ -33,14 +32,12 @@ fn test_match_with_unreachable(x: bool) -> bool {
     }
 }
 
-#[allow(clippy::never_loop)]
 fn test_loop() -> bool {
     loop {
         break true;
     }
 }
 
-#[allow(clippy::never_loop)]
 fn test_loop_with_block() -> bool {
     loop {
         {
@@ -49,7 +46,6 @@ fn test_loop_with_block() -> bool {
     }
 }
 
-#[allow(clippy::never_loop)]
 fn test_loop_with_nests() -> bool {
     loop {
         if true {
@@ -83,15 +79,53 @@ fn test_return_macro() -> String {
     format!("test {}", "test")
 }
 
-fn main() {
+fn macro_branch_test() -> bool {
-    let _ = test_end_of_fn();
+    macro_rules! m {
-    let _ = test_if_block();
+        ($t:expr, $f:expr) => {
-    let _ = test_match(true);
+            if true { $t } else { $f }
-    let _ = test_match_with_unreachable(true);
+        };
-    let _ = test_loop();
+    }
-    let _ = test_loop_with_block();
+    m!(true, false)
-    let _ = test_loop_with_nests();
-    let _ = test_loop_with_if_let();
-    test_closure();
-    let _ = test_return_macro();
 }
+
+fn loop_test() -> bool {
+    'outer: loop {
+        if true {
+            break true;
+        }
+
+        let _ = loop {
+            if false {
+                break 'outer false;
+            }
+            if true {
+                break true;
+            }
+        };
+    }
+}
+
+fn loop_macro_test() -> bool {
+    macro_rules! m {
+        ($e:expr) => {
+            break $e
+        };
+    }
+    loop {
+        m!(true);
+    }
+}
+
+fn divergent_test() -> bool {
+    fn diverge() -> ! {
+        panic!()
+    }
+    diverge()
+}
+
+// issue #6940
+async fn foo() -> bool {
+    true
+}
+
+fn main() {}

src/tools/clippy/tests/ui/implicit_return.stderr

@@ -1,5 +1,5 @@
 error: missing `return` statement
-  --> $DIR/implicit_return.rs:12:5
+  --> $DIR/implicit_return.rs:13:5
    |
 LL |     true
    |     ^^^^ help: add `return` as shown: `return true`
@@ -31,40 +31,79 @@ LL |         false => { true },
    |                    ^^^^ help: add `return` as shown: `return true`
 
 error: missing `return` statement
-  --> $DIR/implicit_return.rs:39:9
+  --> $DIR/implicit_return.rs:37:9
    |
 LL |         break true;
    |         ^^^^^^^^^^ help: change `break` to `return` as shown: `return true`
 
 error: missing `return` statement
-  --> $DIR/implicit_return.rs:47:13
+  --> $DIR/implicit_return.rs:44:13
    |
 LL |             break true;
    |             ^^^^^^^^^^ help: change `break` to `return` as shown: `return true`
 
 error: missing `return` statement
-  --> $DIR/implicit_return.rs:56:13
+  --> $DIR/implicit_return.rs:52:13
    |
 LL |             break true;
    |             ^^^^^^^^^^ help: change `break` to `return` as shown: `return true`
 
 error: missing `return` statement
-  --> $DIR/implicit_return.rs:74:18
+  --> $DIR/implicit_return.rs:70:18
    |
 LL |     let _ = || { true };
    |                  ^^^^ help: add `return` as shown: `return true`
 
 error: missing `return` statement
-  --> $DIR/implicit_return.rs:75:16
+  --> $DIR/implicit_return.rs:71:16
    |
 LL |     let _ = || true;
    |                ^^^^ help: add `return` as shown: `return true`
 
 error: missing `return` statement
-  --> $DIR/implicit_return.rs:83:5
+  --> $DIR/implicit_return.rs:79:5
    |
 LL |     format!("test {}", "test")
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: add `return` as shown: `return format!("test {}", "test")`
 
-error: aborting due to 11 previous errors
+error: missing `return` statement
+  --> $DIR/implicit_return.rs:88:5
+   |
+LL |     m!(true, false)
+   |     ^^^^^^^^^^^^^^^ help: add `return` as shown: `return m!(true, false)`
+
+error: missing `return` statement
+  --> $DIR/implicit_return.rs:94:13
+   |
+LL |             break true;
+   |             ^^^^^^^^^^ help: change `break` to `return` as shown: `return true`
+
+error: missing `return` statement
+  --> $DIR/implicit_return.rs:99:17
+   |
+LL |                 break 'outer false;
+   |                 ^^^^^^^^^^^^^^^^^^ help: change `break` to `return` as shown: `return false`
+
+error: missing `return` statement
+  --> $DIR/implicit_return.rs:114:5
+   |
+LL | /     loop {
+LL | |         m!(true);
+LL | |     }
+   | |_____^
+   |
+help: add `return` as shown
+   |
+LL |     return loop {
+LL |         m!(true);
+LL |     }
+   |
+
+error: missing `return` statement
+  --> $DIR/implicit_return.rs:128:5
+   |
+LL |     true
+   |     ^^^^ help: add `return` as shown: `return true`
+
+error: aborting due to 16 previous errors
 

src/tools/clippy/tests/ui/infinite_loop.rs

@@ -192,11 +192,23 @@ fn while_loop_with_break_and_return() {
     }
 }
 
+fn immutable_condition_false_positive(mut n: u64) -> u32 {
+    let mut count = 0;
+    while {
+        n >>= 1;
+        n != 0
+    } {
+        count += 1;
+    }
+    count
+}
+
 fn main() {
     immutable_condition();
     unused_var();
     used_immutable();
     internally_mutable();
+    immutable_condition_false_positive(5);
 
     let mut c = Counter { count: 0 };
     c.inc_n(5);

src/tools/clippy/tests/ui/needless_collect_indirect.rs

@@ -1,4 +1,4 @@
-use std::collections::{HashMap, VecDeque};
+use std::collections::{BinaryHeap, HashMap, LinkedList, VecDeque};
 
 fn main() {
     let sample = [1; 5];
@@ -43,3 +43,35 @@ fn main() {
             .collect::<Vec<_>>();
     }
 }
+
+mod issue7110 {
+    // #7110 - lint for type annotation cases
+    use super::*;
+
+    fn lint_vec(string: &str) -> usize {
+        let buffer: Vec<&str> = string.split('/').collect();
+        buffer.len()
+    }
+    fn lint_vec_deque() -> usize {
+        let sample = [1; 5];
+        let indirect_len: VecDeque<_> = sample.iter().collect();
+        indirect_len.len()
+    }
+    fn lint_linked_list() -> usize {
+        let sample = [1; 5];
+        let indirect_len: LinkedList<_> = sample.iter().collect();
+        indirect_len.len()
+    }
+    fn lint_binary_heap() -> usize {
+        let sample = [1; 5];
+        let indirect_len: BinaryHeap<_> = sample.iter().collect();
+        indirect_len.len()
+    }
+    fn dont_lint(string: &str) -> usize {
+        let buffer: Vec<&str> = string.split('/').collect();
+        for buff in &buffer {
+            println!("{}", buff);
+        }
+        buffer.len()
+    }
+}

src/tools/clippy/tests/ui/needless_collect_indirect.stderr

@@ -69,5 +69,61 @@ LL |
 LL |     sample.into_iter().any(|x| x == a);
    |
 
-error: aborting due to 5 previous errors
+error: avoid using `collect()` when not needed
+  --> $DIR/needless_collect_indirect.rs:52:51
+   |
+LL |         let buffer: Vec<&str> = string.split('/').collect();
+   |                                                   ^^^^^^^
+LL |         buffer.len()
+   |         ------------ the iterator could be used here instead
+   |
+help: take the original Iterator's count instead of collecting it and finding the length
+   |
+LL |         
+LL |         string.split('/').count()
+   |
+
+error: avoid using `collect()` when not needed
+  --> $DIR/needless_collect_indirect.rs:57:55
+   |
+LL |         let indirect_len: VecDeque<_> = sample.iter().collect();
+   |                                                       ^^^^^^^
+LL |         indirect_len.len()
+   |         ------------------ the iterator could be used here instead
+   |
+help: take the original Iterator's count instead of collecting it and finding the length
+   |
+LL |         
+LL |         sample.iter().count()
+   |
+
+error: avoid using `collect()` when not needed
+  --> $DIR/needless_collect_indirect.rs:62:57
+   |
+LL |         let indirect_len: LinkedList<_> = sample.iter().collect();
+   |                                                         ^^^^^^^
+LL |         indirect_len.len()
+   |         ------------------ the iterator could be used here instead
+   |
+help: take the original Iterator's count instead of collecting it and finding the length
+   |
+LL |         
+LL |         sample.iter().count()
+   |
+
+error: avoid using `collect()` when not needed
+  --> $DIR/needless_collect_indirect.rs:67:57
+   |
+LL |         let indirect_len: BinaryHeap<_> = sample.iter().collect();
+   |                                                         ^^^^^^^
+LL |         indirect_len.len()
+   |         ------------------ the iterator could be used here instead
+   |
+help: take the original Iterator's count instead of collecting it and finding the length
+   |
+LL |         
+LL |         sample.iter().count()
+   |
+
+error: aborting due to 9 previous errors
 

src/tools/clippy/tests/ui/single_char_pattern.fixed

@@ -33,6 +33,8 @@ fn main() {
     x.rmatch_indices('x');
     x.trim_start_matches('x');
     x.trim_end_matches('x');
+    x.strip_prefix('x');
+    x.strip_suffix('x');
     // Make sure we escape characters correctly.
     x.split('\n');
     x.split('\'');

src/tools/clippy/tests/ui/single_char_pattern.rs

@@ -33,6 +33,8 @@ fn main() {
     x.rmatch_indices("x");
     x.trim_start_matches("x");
     x.trim_end_matches("x");
+    x.strip_prefix("x");
+    x.strip_suffix("x");
     // Make sure we escape characters correctly.
     x.split("\n");
     x.split("'");

src/tools/clippy/tests/ui/single_char_pattern.stderr

@@ -121,64 +121,76 @@ LL |     x.trim_end_matches("x");
    |                        ^^^ help: try using a `char` instead: `'x'`
 
 error: single-character string constant used as pattern
-  --> $DIR/single_char_pattern.rs:37:13
+  --> $DIR/single_char_pattern.rs:36:20
+   |
+LL |     x.strip_prefix("x");
+   |                    ^^^ help: try using a `char` instead: `'x'`
+
+error: single-character string constant used as pattern
+  --> $DIR/single_char_pattern.rs:37:20
+   |
+LL |     x.strip_suffix("x");
+   |                    ^^^ help: try using a `char` instead: `'x'`
+
+error: single-character string constant used as pattern
+  --> $DIR/single_char_pattern.rs:39:13
    |
 LL |     x.split("/n");
    |             ^^^^ help: try using a `char` instead: `'/n'`
 
 error: single-character string constant used as pattern
-  --> $DIR/single_char_pattern.rs:38:13
+  --> $DIR/single_char_pattern.rs:40:13
    |
 LL |     x.split("'");
    |             ^^^ help: try using a `char` instead: `'/''`
 
 error: single-character string constant used as pattern
-  --> $DIR/single_char_pattern.rs:39:13
+  --> $DIR/single_char_pattern.rs:41:13
    |
 LL |     x.split("/'");
    |             ^^^^ help: try using a `char` instead: `'/''`
 
 error: single-character string constant used as pattern
-  --> $DIR/single_char_pattern.rs:44:31
+  --> $DIR/single_char_pattern.rs:46:31
    |
 LL |     x.replace(";", ",").split(","); // issue #2978
    |                               ^^^ help: try using a `char` instead: `','`
 
 error: single-character string constant used as pattern
-  --> $DIR/single_char_pattern.rs:45:19
+  --> $DIR/single_char_pattern.rs:47:19
    |
 LL |     x.starts_with("/x03"); // issue #2996
    |                   ^^^^^^ help: try using a `char` instead: `'/x03'`
 
 error: single-character string constant used as pattern
-  --> $DIR/single_char_pattern.rs:52:13
+  --> $DIR/single_char_pattern.rs:54:13
    |
 LL |     x.split(r"a");
    |             ^^^^ help: try using a `char` instead: `'a'`
 
 error: single-character string constant used as pattern
-  --> $DIR/single_char_pattern.rs:53:13
+  --> $DIR/single_char_pattern.rs:55:13
    |
 LL |     x.split(r#"a"#);
    |             ^^^^^^ help: try using a `char` instead: `'a'`
 
 error: single-character string constant used as pattern
-  --> $DIR/single_char_pattern.rs:54:13
+  --> $DIR/single_char_pattern.rs:56:13
    |
 LL |     x.split(r###"a"###);
    |             ^^^^^^^^^^ help: try using a `char` instead: `'a'`
 
 error: single-character string constant used as pattern
-  --> $DIR/single_char_pattern.rs:55:13
+  --> $DIR/single_char_pattern.rs:57:13
    |
 LL |     x.split(r###"'"###);
    |             ^^^^^^^^^^ help: try using a `char` instead: `'/''`
 
 error: single-character string constant used as pattern
-  --> $DIR/single_char_pattern.rs:56:13
+  --> $DIR/single_char_pattern.rs:58:13
    |
 LL |     x.split(r###"#"###);
    |             ^^^^^^^^^^ help: try using a `char` instead: `'#'`
 
-error: aborting due to 30 previous errors
+error: aborting due to 32 previous errors
 

src/tools/clippy/tests/ui/unnecessary_filter_map.rs

@@ -15,3 +15,7 @@ fn main() {
 
     let _ = (0..4).filter_map(i32::checked_abs);
 }
+
+fn filter_map_none_changes_item_type() -> impl Iterator<Item = bool> {
+    "".chars().filter_map(|_| None)
+}

src/tools/clippy/tests/ui/unused_unit.fixed

@@ -80,3 +80,10 @@ fn test2(){}
 
 #[rustfmt::skip]
 fn test3(){}
+
+fn macro_expr() {
+    macro_rules! e {
+        () => (());
+    }
+    e!()
+}

src/tools/clippy/tests/ui/unused_unit.rs

@@ -80,3 +80,10 @@ fn test2() ->(){}
 
 #[rustfmt::skip]
 fn test3()-> (){}
+
+fn macro_expr() {
+    macro_rules! e {
+        () => (());
+    }
+    e!()
+}

src/tools/clippy/util/lintlib.py

@@ -14,7 +14,7 @@ lintname_re = re.compile(r'''pub\s+([A-Z_][A-Z_0-9]*)''')
 group_re = re.compile(r'''\s*([a-z_][a-z_0-9]+)''')
 conf_re = re.compile(r'''define_Conf! {\n([^}]*)\n}''', re.MULTILINE)
 confvar_re = re.compile(
-    r'''/// Lint: ([\w,\s]+)\. (.*)\n\s*\([^,]+,\s+"([^"]+)":\s+([^,]+),\s+([^\.\)]+).*\),''', re.MULTILINE)
+    r'''/// Lint: ([\w,\s]+)\. (.*)\n\s*\(([^:]+):\s*([^\s=]+)\s*=\s*([^\.\)]+).*\),''', re.MULTILINE)
 comment_re = re.compile(r'''\s*/// ?(.*)''')
 
 lint_levels = {