Rollup merge of #111004 - clubby789:migrate-mir-transform, r=oli-obk

Migrate `mir_transform` to translatable diagnostics

cc #100717

Cargo.lock

@@ -3353,6 +3353,7 @@ dependencies = [
  "rustc_middle",
  "rustc_mir_build",
  "rustc_mir_dataflow",
+ "rustc_mir_transform",
  "rustc_monomorphize",
  "rustc_parse",
  "rustc_passes",
@@ -3861,8 +3862,10 @@ dependencies = [
  "rustc_const_eval",
  "rustc_data_structures",
  "rustc_errors",
+ "rustc_fluent_macro",
  "rustc_hir",
  "rustc_index",
+ "rustc_macros",
  "rustc_middle",
  "rustc_mir_dataflow",
  "rustc_serialize",

compiler/rustc_driver_impl/Cargo.toml

@@ -51,6 +51,7 @@ rustc_interface = { path = "../rustc_interface" }
 rustc_ast = { path = "../rustc_ast" }
 rustc_span = { path = "../rustc_span" }
 rustc_hir_analysis = { path = "../rustc_hir_analysis" }
+rustc_mir_transform = { path = "../rustc_mir_transform" }
 
 [target.'cfg(unix)'.dependencies]
 libc = "0.2"
@@ -64,5 +65,8 @@ features = [
 [features]
 llvm = ['rustc_interface/llvm']
 max_level_info = ['rustc_log/max_level_info']
-rustc_use_parallel_compiler = ['rustc_data_structures/rustc_use_parallel_compiler', 'rustc_interface/rustc_use_parallel_compiler',
+rustc_use_parallel_compiler = [
-    'rustc_middle/rustc_use_parallel_compiler']
+    'rustc_data_structures/rustc_use_parallel_compiler',
+    'rustc_interface/rustc_use_parallel_compiler',
+    'rustc_middle/rustc_use_parallel_compiler'
+]

compiler/rustc_driver_impl/src/lib.rs

@@ -99,6 +99,7 @@ pub static DEFAULT_LOCALE_RESOURCES: &[&str] = &[
     rustc_middle::DEFAULT_LOCALE_RESOURCE,
     rustc_mir_build::DEFAULT_LOCALE_RESOURCE,
     rustc_mir_dataflow::DEFAULT_LOCALE_RESOURCE,
+    rustc_mir_transform::DEFAULT_LOCALE_RESOURCE,
     rustc_monomorphize::DEFAULT_LOCALE_RESOURCE,
     rustc_parse::DEFAULT_LOCALE_RESOURCE,
     rustc_passes::DEFAULT_LOCALE_RESOURCE,

compiler/rustc_errors/src/diagnostic_builder.rs

@@ -571,6 +571,14 @@ impl<'a, G: EmissionGuarantee> DiagnosticBuilder<'a, G> {
         Some((diagnostic, handler))
     }
 
+    /// Retrieves the [`Handler`] if available
+    pub fn handler(&self) -> Option<&Handler> {
+        match self.inner.state {
+            DiagnosticBuilderState::Emittable(handler) => Some(handler),
+            DiagnosticBuilderState::AlreadyEmittedOrDuringCancellation => None,
+        }
+    }
+
     /// Buffers the diagnostic for later emission,
     /// unless handler has disabled such buffering.
     pub fn buffer(self, buffered_diagnostics: &mut Vec<Diagnostic>) {

compiler/rustc_mir_transform/Cargo.toml

@@ -24,6 +24,8 @@ rustc_session = { path = "../rustc_session" }
 rustc_target = { path = "../rustc_target" }
 rustc_trait_selection = { path = "../rustc_trait_selection" }
 rustc_span = { path = "../rustc_span" }
+rustc_fluent_macro = { path = "../rustc_fluent_macro" }
+rustc_macros = { path = "../rustc_macros" }
 
 [dev-dependencies]
 coverage_test_macros = { path = "src/coverage/test_macros" }

compiler/rustc_mir_transform/messages.ftl

@@ -0,0 +1,66 @@
+mir_transform_const_modify = attempting to modify a `const` item
+    .note = each usage of a `const` item creates a new temporary; the original `const` item will not be modified
+
+mir_transform_const_mut_borrow = taking a mutable reference to a `const` item
+    .note = each usage of a `const` item creates a new temporary
+    .note2 = the mutable reference will refer to this temporary, not the original `const` item
+    .note3 = mutable reference created due to call to this method
+
+mir_transform_const_defined_here = `const` item defined here
+
+mir_transform_unaligned_packed_ref = reference to packed field is unaligned
+    .note = packed structs are only aligned by one byte, and many modern architectures penalize unaligned field accesses
+    .note_ub = creating a misaligned reference is undefined behavior (even if that reference is never dereferenced)
+    .help = copy the field contents to a local variable, or replace the reference with a raw pointer and use `read_unaligned`/`write_unaligned` (loads and stores via `*p` must be properly aligned even when using raw pointers)
+
+mir_transform_unused_unsafe = unnecessary `unsafe` block
+    .label = because it's nested under this `unsafe` block
+
+mir_transform_requires_unsafe = {$details} is unsafe and requires unsafe {$op_in_unsafe_fn_allowed ->
+    [true] function or block
+    *[false] block
+    }
+    .not_inherited = items do not inherit unsafety from separate enclosing items
+
+mir_transform_call_to_unsafe_label = call to unsafe function
+mir_transform_call_to_unsafe_note = consult the function's documentation for information on how to avoid undefined behavior
+mir_transform_use_of_asm_label = use of inline assembly
+mir_transform_use_of_asm_note = inline assembly is entirely unchecked and can cause undefined behavior
+mir_transform_initializing_valid_range_label = initializing type with `rustc_layout_scalar_valid_range` attr
+mir_transform_initializing_valid_range_note = initializing a layout restricted type's field with a value outside the valid range is undefined behavior
+mir_transform_const_ptr2int_label = cast of pointer to int
+mir_transform_const_ptr2int_note = casting pointers to integers in constants
+mir_transform_use_of_static_mut_label = use of mutable static
+mir_transform_use_of_static_mut_note = mutable statics can be mutated by multiple threads: aliasing violations or data races will cause undefined behavior
+mir_transform_use_of_extern_static_label = use of extern static
+mir_transform_use_of_extern_static_note = extern statics are not controlled by the Rust type system: invalid data, aliasing violations or data races will cause undefined behavior
+mir_transform_deref_ptr_label = dereference of raw pointer
+mir_transform_deref_ptr_note = raw pointers may be null, dangling or unaligned; they can violate aliasing rules and cause data races: all of these are undefined behavior
+mir_transform_union_access_label = access to union field
+mir_transform_union_access_note = the field may not be properly initialized: using uninitialized data will cause undefined behavior
+mir_transform_mutation_layout_constrained_label = mutation of layout constrained field
+mir_transform_mutation_layout_constrained_note = mutating layout constrained fields cannot statically be checked for valid values
+mir_transform_mutation_layout_constrained_borrow_label = borrow of layout constrained field with interior mutability
+mir_transform_mutation_layout_constrained_borrow_note = references to fields of layout constrained fields lose the constraints. Coupled with interior mutability, the field can be changed to invalid values
+mir_transform_target_feature_call_label = call to function with `#[target_feature]`
+mir_transform_target_feature_call_note = can only be called if the required target features are available
+
+mir_transform_unsafe_op_in_unsafe_fn = {$details} is unsafe and requires unsafe block (error E0133)
+
+mir_transform_arithmetic_overflow = this arithmetic operation will overflow
+mir_transform_operation_will_panic = this operation will panic at runtime
+
+mir_transform_ffi_unwind_call = call to {$foreign ->
+    [true] foreign function
+    *[false] function pointer
+    } with FFI-unwind ABI
+
+mir_transform_fn_item_ref = taking a reference to a function item does not give a function pointer
+    .suggestion = cast `{$ident}` to obtain a function pointer
+
+mir_transform_must_not_suspend = {$pre}`{$def_path}`{$post} held across a suspend point, but should not be
+    .label = the value is held across this suspend point
+    .note = {$reason}
+    .help = consider using a block (`{"{ ... }"}`) to shrink the value's scope, ending before the suspend point
+
+mir_transform_simd_shuffle_last_const = last argument of `simd_shuffle` is required to be a `const` item

compiler/rustc_mir_transform/src/check_const_item_mutation.rs

@@ -1,11 +1,12 @@
-use rustc_errors::{DiagnosticBuilder, DiagnosticMessage};
+use rustc_hir::HirId;
 use rustc_middle::mir::visit::Visitor;
 use rustc_middle::mir::*;
 use rustc_middle::ty::TyCtxt;
 use rustc_session::lint::builtin::CONST_ITEM_MUTATION;
 use rustc_span::def_id::DefId;
+use rustc_span::Span;
 
-use crate::MirLint;
+use crate::{errors, MirLint};
 
 pub struct CheckConstItemMutation;
 
@@ -58,16 +59,14 @@ impl<'tcx> ConstMutationChecker<'_, 'tcx> {
         }
     }
 
-    fn lint_const_item_usage(
+    /// If we should lint on this usage, return the [`HirId`], source [`Span`]
+    /// and [`Span`] of the const item to use in the lint.
+    fn should_lint_const_item_usage(
         &self,
         place: &Place<'tcx>,
         const_item: DefId,
         location: Location,
-        msg: impl Into<DiagnosticMessage>,
+    ) -> Option<(HirId, Span, Span)> {
-        decorate: impl for<'a, 'b> FnOnce(
-            &'a mut DiagnosticBuilder<'b, ()>,
-        ) -> &'a mut DiagnosticBuilder<'b, ()>,
-    ) {
         // Don't lint on borrowing/assigning when a dereference is involved.
         // If we 'leave' the temporary via a dereference, we must
         // be modifying something else
@@ -83,16 +82,9 @@ impl<'tcx> ConstMutationChecker<'_, 'tcx> {
                 .assert_crate_local()
                 .lint_root;
 
-            self.tcx.struct_span_lint_hir(
+            Some((lint_root, source_info.span, self.tcx.def_span(const_item)))
-                CONST_ITEM_MUTATION,
+        } else {
-                lint_root,
+            None
-                source_info.span,
-                msg,
-                |lint| {
-                    decorate(lint)
-                        .span_note(self.tcx.def_span(const_item), "`const` item defined here")
-                },
-            );
         }
     }
 }
@@ -104,10 +96,14 @@ impl<'tcx> Visitor<'tcx> for ConstMutationChecker<'_, 'tcx> {
             // Assigning directly to a constant (e.g. `FOO = true;`) is a hard error,
             // so emitting a lint would be redundant.
             if !lhs.projection.is_empty() {
-                if let Some(def_id) = self.is_const_item_without_destructor(lhs.local) {
+                if let Some(def_id) = self.is_const_item_without_destructor(lhs.local)
-                    self.lint_const_item_usage(&lhs, def_id, loc, "attempting to modify a `const` item",|lint| {
+                    && let Some((lint_root, span, item)) = self.should_lint_const_item_usage(&lhs, def_id, loc) {
-                        lint.note("each usage of a `const` item creates a new temporary; the original `const` item will not be modified")
+                        self.tcx.emit_spanned_lint(
-                    })
+                            CONST_ITEM_MUTATION,
+                            lint_root,
+                            span,
+                            errors::ConstMutate::Modify { konst: item }
+                        );
                 }
             }
             // We are looking for MIR of the form:
@@ -143,17 +139,22 @@ impl<'tcx> Visitor<'tcx> for ConstMutationChecker<'_, 'tcx> {
                 });
                 let lint_loc =
                     if method_did.is_some() { self.body.terminator_loc(loc.block) } else { loc };
-                self.lint_const_item_usage(place, def_id, lint_loc, "taking a mutable reference to a `const` item", |lint| {
-                    lint
-                        .note("each usage of a `const` item creates a new temporary")
-                        .note("the mutable reference will refer to this temporary, not the original `const` item");
 
-                    if let Some((method_did, _substs)) = method_did {
+                let method_call = if let Some((method_did, _)) = method_did {
-                        lint.span_note(self.tcx.def_span(method_did), "mutable reference created due to call to this method");
+                    Some(self.tcx.def_span(method_did))
-                    }
+                } else {
-
+                    None
-                    lint
+                };
-                });
+                if let Some((lint_root, span, item)) =
+                    self.should_lint_const_item_usage(place, def_id, lint_loc)
+                {
+                    self.tcx.emit_spanned_lint(
+                        CONST_ITEM_MUTATION,
+                        lint_root,
+                        span,
+                        errors::ConstMutate::MutBorrow { method_call, konst: item },
+                    );
+                }
             }
         }
         self.super_rvalue(rvalue, loc);

compiler/rustc_mir_transform/src/check_packed_ref.rs

@@ -1,10 +1,9 @@
-use rustc_errors::struct_span_err;
 use rustc_middle::mir::visit::{PlaceContext, Visitor};
 use rustc_middle::mir::*;
 use rustc_middle::ty::{self, TyCtxt};
 
-use crate::util;
 use crate::MirLint;
+use crate::{errors, util};
 
 pub struct CheckPackedRef;
 
@@ -49,25 +48,7 @@ impl<'tcx> Visitor<'tcx> for PackedRefChecker<'_, 'tcx> {
                     // shouldn't do.
                     span_bug!(self.source_info.span, "builtin derive created an unaligned reference");
                 } else {
-                    struct_span_err!(
+                    self.tcx.sess.emit_err(errors::UnalignedPackedRef { span: self.source_info.span });
-                        self.tcx.sess,
-                        self.source_info.span,
-                        E0793,
-                        "reference to packed field is unaligned"
-                    )
-                    .note(
-                        "packed structs are only aligned by one byte, and many modern architectures \
-                        penalize unaligned field accesses"
-                    )
-                    .note(
-                        "creating a misaligned reference is undefined behavior (even if that \
-                        reference is never dereferenced)",
-                    ).help(
-                        "copy the field contents to a local variable, or replace the \
-                        reference with a raw pointer and use `read_unaligned`/`write_unaligned` \
-                        (loads and stores via `*p` must be properly aligned even when using raw pointers)"
-                    )
-                    .emit();
                 }
             }
         }

compiler/rustc_mir_transform/src/check_unsafety.rs

@@ -1,5 +1,4 @@
 use rustc_data_structures::unord::{UnordItems, UnordSet};
-use rustc_errors::struct_span_err;
 use rustc_hir as hir;
 use rustc_hir::def::DefKind;
 use rustc_hir::def_id::{DefId, LocalDefId};
@@ -15,6 +14,8 @@ use rustc_session::lint::Level;
 
 use std::ops::Bound;
 
+use crate::errors;
+
 pub struct UnsafetyChecker<'a, 'tcx> {
     body: &'a Body<'tcx>,
     body_did: LocalDefId,
@@ -509,21 +510,12 @@ fn unsafety_check_result(tcx: TyCtxt<'_>, def: LocalDefId) -> &UnsafetyCheckResu
 
 fn report_unused_unsafe(tcx: TyCtxt<'_>, kind: UnusedUnsafe, id: HirId) {
     let span = tcx.sess.source_map().guess_head_span(tcx.hir().span(id));
-    let msg = "unnecessary `unsafe` block";
+    let nested_parent = if let UnusedUnsafe::InUnsafeBlock(id) = kind {
-    tcx.struct_span_lint_hir(UNUSED_UNSAFE, id, span, msg, |lint| {
+        Some(tcx.sess.source_map().guess_head_span(tcx.hir().span(id)))
-        lint.span_label(span, msg);
+    } else {
-        match kind {
+        None
-            UnusedUnsafe::Unused => {}
+    };
-            UnusedUnsafe::InUnsafeBlock(id) => {
+    tcx.emit_spanned_lint(UNUSED_UNSAFE, id, span, errors::UnusedUnsafe { span, nested_parent });
-                lint.span_label(
-                    tcx.sess.source_map().guess_head_span(tcx.hir().span(id)),
-                    "because it's nested under this `unsafe` block",
-                );
-            }
-        }
-
-        lint
-    });
 }
 
 pub fn check_unsafety(tcx: TyCtxt<'_>, def_id: LocalDefId) {
@@ -537,26 +529,11 @@ pub fn check_unsafety(tcx: TyCtxt<'_>, def_id: LocalDefId) {
     let UnsafetyCheckResult { violations, unused_unsafes, .. } = tcx.unsafety_check_result(def_id);
 
     for &UnsafetyViolation { source_info, lint_root, kind, details } in violations.iter() {
-        let (description, note) = details.description_and_note();
+        let details = errors::RequiresUnsafeDetail { violation: details, span: source_info.span };
 
         match kind {
             UnsafetyViolationKind::General => {
-                // once
+                let op_in_unsafe_fn_allowed = unsafe_op_in_unsafe_fn_allowed(tcx, lint_root);
-                let unsafe_fn_msg = if unsafe_op_in_unsafe_fn_allowed(tcx, lint_root) {
-                    " function or"
-                } else {
-                    ""
-                };
-
-                let mut err = struct_span_err!(
-                    tcx.sess,
-                    source_info.span,
-                    E0133,
-                    "{} is unsafe and requires unsafe{} block",
-                    description,
-                    unsafe_fn_msg,
-                );
-                err.span_label(source_info.span, description).note(note);
                 let note_non_inherited = tcx.hir().parent_iter(lint_root).find(|(id, node)| {
                     if let Node::Expr(block) = node
                         && let ExprKind::Block(block, _) = block.kind
@@ -572,22 +549,23 @@ pub fn check_unsafety(tcx: TyCtxt<'_>, def_id: LocalDefId) {
                         false
                     }
                 });
-                if let Some((id, _)) = note_non_inherited {
+                let enclosing = if let Some((id, _)) = note_non_inherited {
-                    let span = tcx.hir().span(id);
+                    Some(tcx.sess.source_map().guess_head_span(tcx.hir().span(id)))
-                    err.span_label(
+                } else {
-                        tcx.sess.source_map().guess_head_span(span),
+                    None
-                        "items do not inherit unsafety from separate enclosing items",
+                };
-                    );
+                tcx.sess.emit_err(errors::RequiresUnsafe {
-                }
+                    span: source_info.span,
-
+                    enclosing,
-                err.emit();
+                    details,
+                    op_in_unsafe_fn_allowed,
+                });
             }
-            UnsafetyViolationKind::UnsafeFn => tcx.struct_span_lint_hir(
+            UnsafetyViolationKind::UnsafeFn => tcx.emit_spanned_lint(
                 UNSAFE_OP_IN_UNSAFE_FN,
                 lint_root,
                 source_info.span,
-                format!("{} is unsafe and requires unsafe block (error E0133)", description,),
+                errors::UnsafeOpInUnsafeFn { details },
-                |lint| lint.span_label(source_info.span, description).note(note),
             ),
         }
     }

compiler/rustc_mir_transform/src/const_prop_lint.rs

@@ -1,6 +1,8 @@
 //! Propagates constants for early reporting of statically known
 //! assertion failures
 
+use std::fmt::Debug;
+
 use either::Left;
 
 use rustc_const_eval::interpret::Immediate;
@@ -17,7 +19,6 @@ use rustc_middle::ty::InternalSubsts;
 use rustc_middle::ty::{
     self, ConstInt, Instance, ParamEnv, ScalarInt, Ty, TyCtxt, TypeVisitableExt,
 };
-use rustc_session::lint;
 use rustc_span::Span;
 use rustc_target::abi::{HasDataLayout, Size, TargetDataLayout};
 use rustc_trait_selection::traits;
@@ -25,6 +26,7 @@ use rustc_trait_selection::traits;
 use crate::const_prop::CanConstProp;
 use crate::const_prop::ConstPropMachine;
 use crate::const_prop::ConstPropMode;
+use crate::errors::AssertLint;
 use crate::MirLint;
 
 /// The maximum number of bytes that we'll allocate space for a local or the return value.
@@ -311,18 +313,9 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
         }
     }
 
-    fn report_assert_as_lint(
+    fn report_assert_as_lint(&self, source_info: &SourceInfo, lint: AssertLint<impl Debug>) {
-        &self,
-        lint: &'static lint::Lint,
-        location: Location,
-        message: &'static str,
-        panic: AssertKind<impl std::fmt::Debug>,
-    ) {
-        let source_info = self.body().source_info(location);
         if let Some(lint_root) = self.lint_root(*source_info) {
-            self.tcx.struct_span_lint_hir(lint, lint_root, source_info.span, message, |lint| {
+            self.tcx.emit_spanned_lint(lint.lint(), lint_root, source_info.span, lint);
-                lint.span_label(source_info.span, format!("{:?}", panic))
-            });
         }
     }
 
@@ -335,11 +328,13 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
             // `AssertKind` only has an `OverflowNeg` variant, so make sure that is
             // appropriate to use.
             assert_eq!(op, UnOp::Neg, "Neg is the only UnOp that can overflow");
+            let source_info = self.body().source_info(location);
             self.report_assert_as_lint(
-                lint::builtin::ARITHMETIC_OVERFLOW,
+                source_info,
-                location,
+                AssertLint::ArithmeticOverflow(
-                "this arithmetic operation will overflow",
+                    source_info.span,
-                AssertKind::OverflowNeg(val.to_const_int()),
+                    AssertKind::OverflowNeg(val.to_const_int()),
+                ),
             );
             return None;
         }
@@ -370,23 +365,23 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
             let r_bits = r.to_scalar().to_bits(right_size).ok();
             if r_bits.map_or(false, |b| b >= left_size.bits() as u128) {
                 debug!("check_binary_op: reporting assert for {:?}", location);
+                let source_info = self.body().source_info(location);
+                let panic = AssertKind::Overflow(
+                    op,
+                    match l {
+                        Some(l) => l.to_const_int(),
+                        // Invent a dummy value, the diagnostic ignores it anyway
+                        None => ConstInt::new(
+                            ScalarInt::try_from_uint(1_u8, left_size).unwrap(),
+                            left_ty.is_signed(),
+                            left_ty.is_ptr_sized_integral(),
+                        ),
+                    },
+                    r.to_const_int(),
+                );
                 self.report_assert_as_lint(
-                    lint::builtin::ARITHMETIC_OVERFLOW,
+                    source_info,
-                    location,
+                    AssertLint::ArithmeticOverflow(source_info.span, panic),
-                    "this arithmetic operation will overflow",
-                    AssertKind::Overflow(
-                        op,
-                        match l {
-                            Some(l) => l.to_const_int(),
-                            // Invent a dummy value, the diagnostic ignores it anyway
-                            None => ConstInt::new(
-                                ScalarInt::try_from_uint(1_u8, left_size).unwrap(),
-                                left_ty.is_signed(),
-                                left_ty.is_ptr_sized_integral(),
-                            ),
-                        },
-                        r.to_const_int(),
-                    ),
                 );
                 return None;
             }
@@ -398,11 +393,13 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
                 let (_res, overflow, _ty) = this.ecx.overflowing_binary_op(op, &l, &r)?;
                 Ok(overflow)
             })? {
+                let source_info = self.body().source_info(location);
                 self.report_assert_as_lint(
-                    lint::builtin::ARITHMETIC_OVERFLOW,
+                    source_info,
-                    location,
+                    AssertLint::ArithmeticOverflow(
-                    "this arithmetic operation will overflow",
+                        source_info.span,
-                    AssertKind::Overflow(op, l.to_const_int(), r.to_const_int()),
+                        AssertKind::Overflow(op, l.to_const_int(), r.to_const_int()),
+                    ),
                 );
                 return None;
             }
@@ -543,11 +540,10 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
                 // Need proper const propagator for these.
                 _ => return None,
             };
+            let source_info = self.body().source_info(location);
             self.report_assert_as_lint(
-                lint::builtin::UNCONDITIONAL_PANIC,
+                source_info,
-                location,
+                AssertLint::UnconditionalPanic(source_info.span, msg),
-                "this operation will panic at runtime",
-                msg,
             );
         }
 

compiler/rustc_mir_transform/src/errors.rs

@@ -0,0 +1,245 @@
+use rustc_errors::{
+    DecorateLint, DiagnosticBuilder, DiagnosticMessage, EmissionGuarantee, Handler, IntoDiagnostic,
+};
+use rustc_macros::{Diagnostic, LintDiagnostic, Subdiagnostic};
+use rustc_middle::mir::{AssertKind, UnsafetyViolationDetails};
+use rustc_session::lint::{self, Lint};
+use rustc_span::Span;
+
+#[derive(LintDiagnostic)]
+pub(crate) enum ConstMutate {
+    #[diag(mir_transform_const_modify)]
+    #[note]
+    Modify {
+        #[note(mir_transform_const_defined_here)]
+        konst: Span,
+    },
+    #[diag(mir_transform_const_mut_borrow)]
+    #[note]
+    #[note(mir_transform_note2)]
+    MutBorrow {
+        #[note(mir_transform_note3)]
+        method_call: Option<Span>,
+        #[note(mir_transform_const_defined_here)]
+        konst: Span,
+    },
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_transform_unaligned_packed_ref, code = "E0793")]
+#[note]
+#[note(mir_transform_note_ub)]
+#[help]
+pub(crate) struct UnalignedPackedRef {
+    #[primary_span]
+    pub span: Span,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_transform_unused_unsafe)]
+pub(crate) struct UnusedUnsafe {
+    #[label(mir_transform_unused_unsafe)]
+    pub span: Span,
+    #[label]
+    pub nested_parent: Option<Span>,
+}
+
+pub(crate) struct RequiresUnsafe {
+    pub span: Span,
+    pub details: RequiresUnsafeDetail,
+    pub enclosing: Option<Span>,
+    pub op_in_unsafe_fn_allowed: bool,
+}
+
+// The primary message for this diagnostic should be '{$label} is unsafe and...',
+// so we need to eagerly translate the label here, which isn't supported by the derive API
+// We could also exhaustively list out the primary messages for all unsafe violations,
+// but this would result in a lot of duplication.
+impl<'sess, G: EmissionGuarantee> IntoDiagnostic<'sess, G> for RequiresUnsafe {
+    #[track_caller]
+    fn into_diagnostic(self, handler: &'sess Handler) -> DiagnosticBuilder<'sess, G> {
+        let mut diag =
+            handler.struct_diagnostic(crate::fluent_generated::mir_transform_requires_unsafe);
+        diag.code(rustc_errors::DiagnosticId::Error("E0133".to_string()));
+        diag.set_span(self.span);
+        diag.span_label(self.span, self.details.label());
+        diag.note(self.details.note());
+        let desc = handler.eagerly_translate_to_string(self.details.label(), [].into_iter());
+        diag.set_arg("details", desc);
+        diag.set_arg("op_in_unsafe_fn_allowed", self.op_in_unsafe_fn_allowed);
+        if let Some(sp) = self.enclosing {
+            diag.span_label(sp, crate::fluent_generated::mir_transform_not_inherited);
+        }
+        diag
+    }
+}
+
+#[derive(Copy, Clone)]
+pub(crate) struct RequiresUnsafeDetail {
+    pub span: Span,
+    pub violation: UnsafetyViolationDetails,
+}
+
+impl RequiresUnsafeDetail {
+    fn note(self) -> DiagnosticMessage {
+        use UnsafetyViolationDetails::*;
+        match self.violation {
+            CallToUnsafeFunction => crate::fluent_generated::mir_transform_call_to_unsafe_note,
+            UseOfInlineAssembly => crate::fluent_generated::mir_transform_use_of_asm_note,
+            InitializingTypeWith => {
+                crate::fluent_generated::mir_transform_initializing_valid_range_note
+            }
+            CastOfPointerToInt => crate::fluent_generated::mir_transform_const_ptr2int_note,
+            UseOfMutableStatic => crate::fluent_generated::mir_transform_use_of_static_mut_note,
+            UseOfExternStatic => crate::fluent_generated::mir_transform_use_of_extern_static_note,
+            DerefOfRawPointer => crate::fluent_generated::mir_transform_deref_ptr_note,
+            AccessToUnionField => crate::fluent_generated::mir_transform_union_access_note,
+            MutationOfLayoutConstrainedField => {
+                crate::fluent_generated::mir_transform_mutation_layout_constrained_note
+            }
+            BorrowOfLayoutConstrainedField => {
+                crate::fluent_generated::mir_transform_mutation_layout_constrained_borrow_note
+            }
+            CallToFunctionWith => crate::fluent_generated::mir_transform_target_feature_call_note,
+        }
+    }
+
+    fn label(self) -> DiagnosticMessage {
+        use UnsafetyViolationDetails::*;
+        match self.violation {
+            CallToUnsafeFunction => crate::fluent_generated::mir_transform_call_to_unsafe_label,
+            UseOfInlineAssembly => crate::fluent_generated::mir_transform_use_of_asm_label,
+            InitializingTypeWith => {
+                crate::fluent_generated::mir_transform_initializing_valid_range_label
+            }
+            CastOfPointerToInt => crate::fluent_generated::mir_transform_const_ptr2int_label,
+            UseOfMutableStatic => crate::fluent_generated::mir_transform_use_of_static_mut_label,
+            UseOfExternStatic => crate::fluent_generated::mir_transform_use_of_extern_static_label,
+            DerefOfRawPointer => crate::fluent_generated::mir_transform_deref_ptr_label,
+            AccessToUnionField => crate::fluent_generated::mir_transform_union_access_label,
+            MutationOfLayoutConstrainedField => {
+                crate::fluent_generated::mir_transform_mutation_layout_constrained_label
+            }
+            BorrowOfLayoutConstrainedField => {
+                crate::fluent_generated::mir_transform_mutation_layout_constrained_borrow_label
+            }
+            CallToFunctionWith => crate::fluent_generated::mir_transform_target_feature_call_label,
+        }
+    }
+}
+
+pub(crate) struct UnsafeOpInUnsafeFn {
+    pub details: RequiresUnsafeDetail,
+}
+
+impl<'a> DecorateLint<'a, ()> for UnsafeOpInUnsafeFn {
+    #[track_caller]
+    fn decorate_lint<'b>(
+        self,
+        diag: &'b mut DiagnosticBuilder<'a, ()>,
+    ) -> &'b mut DiagnosticBuilder<'a, ()> {
+        let desc = diag
+            .handler()
+            .expect("lint should not yet be emitted")
+            .eagerly_translate_to_string(self.details.label(), [].into_iter());
+        diag.set_arg("details", desc);
+        diag.span_label(self.details.span, self.details.label());
+        diag.note(self.details.note());
+        diag
+    }
+
+    fn msg(&self) -> DiagnosticMessage {
+        crate::fluent_generated::mir_transform_unsafe_op_in_unsafe_fn
+    }
+}
+
+pub(crate) enum AssertLint<P> {
+    ArithmeticOverflow(Span, AssertKind<P>),
+    UnconditionalPanic(Span, AssertKind<P>),
+}
+
+impl<'a, P: std::fmt::Debug> DecorateLint<'a, ()> for AssertLint<P> {
+    fn decorate_lint<'b>(
+        self,
+        diag: &'b mut DiagnosticBuilder<'a, ()>,
+    ) -> &'b mut DiagnosticBuilder<'a, ()> {
+        diag.span_label(self.span(), format!("{:?}", self.panic()));
+        diag
+    }
+
+    fn msg(&self) -> DiagnosticMessage {
+        match self {
+            AssertLint::ArithmeticOverflow(..) => {
+                crate::fluent_generated::mir_transform_arithmetic_overflow
+            }
+            AssertLint::UnconditionalPanic(..) => {
+                crate::fluent_generated::mir_transform_operation_will_panic
+            }
+        }
+    }
+}
+
+impl<P> AssertLint<P> {
+    pub fn lint(&self) -> &'static Lint {
+        match self {
+            AssertLint::ArithmeticOverflow(..) => lint::builtin::ARITHMETIC_OVERFLOW,
+            AssertLint::UnconditionalPanic(..) => lint::builtin::UNCONDITIONAL_PANIC,
+        }
+    }
+    pub fn span(&self) -> Span {
+        match self {
+            AssertLint::ArithmeticOverflow(sp, _) | AssertLint::UnconditionalPanic(sp, _) => *sp,
+        }
+    }
+    pub fn panic(&self) -> &AssertKind<P> {
+        match self {
+            AssertLint::ArithmeticOverflow(_, p) | AssertLint::UnconditionalPanic(_, p) => p,
+        }
+    }
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_transform_ffi_unwind_call)]
+pub(crate) struct FfiUnwindCall {
+    #[label(mir_transform_ffi_unwind_call)]
+    pub span: Span,
+    pub foreign: bool,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_transform_fn_item_ref)]
+pub(crate) struct FnItemRef {
+    #[suggestion(code = "{sugg}", applicability = "unspecified")]
+    pub span: Span,
+    pub sugg: String,
+    pub ident: String,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_transform_must_not_suspend)]
+pub(crate) struct MustNotSupend<'a> {
+    #[label]
+    pub yield_sp: Span,
+    #[subdiagnostic]
+    pub reason: Option<MustNotSuspendReason>,
+    #[help]
+    pub src_sp: Span,
+    pub pre: &'a str,
+    pub def_path: String,
+    pub post: &'a str,
+}
+
+#[derive(Subdiagnostic)]
+#[note(mir_transform_note)]
+pub(crate) struct MustNotSuspendReason {
+    #[primary_span]
+    pub span: Span,
+    pub reason: String,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_transform_simd_shuffle_last_const)]
+pub(crate) struct SimdShuffleLastConst {
+    #[primary_span]
+    pub span: Span,
+}

compiler/rustc_mir_transform/src/ffi_unwind_calls.rs

@@ -8,6 +8,8 @@ use rustc_session::lint::builtin::FFI_UNWIND_CALLS;
 use rustc_target::spec::abi::Abi;
 use rustc_target::spec::PanicStrategy;
 
+use crate::errors;
+
 fn abi_can_unwind(abi: Abi) -> bool {
     use Abi::*;
     match abi {
@@ -107,13 +109,13 @@ fn has_ffi_unwind_calls(tcx: TyCtxt<'_>, local_def_id: LocalDefId) -> bool {
                 .lint_root;
             let span = terminator.source_info.span;
 
-            let msg = match fn_def_id {
+            let foreign = fn_def_id.is_some();
-                Some(_) => "call to foreign function with FFI-unwind ABI",
+            tcx.emit_spanned_lint(
-                None => "call to function pointer with FFI-unwind ABI",
+                FFI_UNWIND_CALLS,
-            };
+                lint_root,
-            tcx.struct_span_lint_hir(FFI_UNWIND_CALLS, lint_root, span, msg, |lint| {
+                span,
-                lint.span_label(span, msg)
+                errors::FfiUnwindCall { span, foreign },
-            });
+            );
 
             tainted = true;
         }

compiler/rustc_mir_transform/src/function_item_references.rs

@@ -1,5 +1,4 @@
 use itertools::Itertools;
-use rustc_errors::Applicability;
 use rustc_hir::def_id::DefId;
 use rustc_middle::mir::visit::Visitor;
 use rustc_middle::mir::*;
@@ -8,7 +7,7 @@ use rustc_session::lint::builtin::FUNCTION_ITEM_REFERENCES;
 use rustc_span::{symbol::sym, Span};
 use rustc_target::spec::abi::Abi;
 
-use crate::MirLint;
+use crate::{errors, MirLint};
 
 pub struct FunctionItemReferences;
 
@@ -174,27 +173,21 @@ impl<'tcx> FunctionItemRefChecker<'_, 'tcx> {
         let num_args = fn_sig.inputs().map_bound(|inputs| inputs.len()).skip_binder();
         let variadic = if fn_sig.c_variadic() { ", ..." } else { "" };
         let ret = if fn_sig.output().skip_binder().is_unit() { "" } else { " -> _" };
-        self.tcx.struct_span_lint_hir(
+        let sugg = format!(
+            "{} as {}{}fn({}{}){}",
+            if params.is_empty() { ident.clone() } else { format!("{}::<{}>", ident, params) },
+            unsafety,
+            abi,
+            vec!["_"; num_args].join(", "),
+            variadic,
+            ret,
+        );
+
+        self.tcx.emit_spanned_lint(
             FUNCTION_ITEM_REFERENCES,
             lint_root,
             span,
-            "taking a reference to a function item does not give a function pointer",
+            errors::FnItemRef { span, sugg, ident },
-            |lint| {
-                lint.span_suggestion(
-                    span,
-                    format!("cast `{}` to obtain a function pointer", ident),
-                    format!(
-                        "{} as {}{}fn({}{}){}",
-                        if params.is_empty() { ident } else { format!("{}::<{}>", ident, params) },
-                        unsafety,
-                        abi,
-                        vec!["_"; num_args].join(", "),
-                        variadic,
-                        ret,
-                    ),
-                    Applicability::Unspecified,
-                )
-            },
         );
     }
 }

compiler/rustc_mir_transform/src/generator.rs

@@ -51,6 +51,7 @@
 //! Otherwise it drops all the values in scope at the last suspension point.
 
 use crate::deref_separator::deref_finder;
+use crate::errors;
 use crate::simplify;
 use crate::MirPass;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
@@ -1891,36 +1892,21 @@ fn check_must_not_suspend_def(
     data: SuspendCheckData<'_>,
 ) -> bool {
     if let Some(attr) = tcx.get_attr(def_id, sym::must_not_suspend) {
-        let msg = rustc_errors::DelayDm(|| {
+        let reason = attr.value_str().map(|s| errors::MustNotSuspendReason {
-            format!(
+            span: data.source_span,
-                "{}`{}`{} held across a suspend point, but should not be",
+            reason: s.as_str().to_string(),
-                data.descr_pre,
-                tcx.def_path_str(def_id),
-                data.descr_post,
-            )
         });
-        tcx.struct_span_lint_hir(
+        tcx.emit_spanned_lint(
             rustc_session::lint::builtin::MUST_NOT_SUSPEND,
             hir_id,
             data.source_span,
-            msg,
+            errors::MustNotSupend {
-            |lint| {
+                yield_sp: data.yield_span,
-                // add span pointing to the offending yield/await
+                reason,
-                lint.span_label(data.yield_span, "the value is held across this suspend point");
+                src_sp: data.source_span,
-
+                pre: data.descr_pre,
-                // Add optional reason note
+                def_path: tcx.def_path_str(def_id),
-                if let Some(note) = attr.value_str() {
+                post: data.descr_post,
-                    // FIXME(guswynn): consider formatting this better
-                    lint.span_note(data.source_span, note.as_str());
-                }
-
-                // Add some quick suggestions on what to do
-                // FIXME: can `drop` work as a suggestion here as well?
-                lint.span_help(
-                    data.source_span,
-                    "consider using a block (`{ ... }`) \
-                    to shrink the value's scope, ending before the suspend point",
-                )
             },
         );
 

compiler/rustc_mir_transform/src/lib.rs

@@ -1,4 +1,6 @@
 #![allow(rustc::potential_query_instability)]
+#![deny(rustc::untranslatable_diagnostic)]
+#![deny(rustc::diagnostic_outside_of_impl)]
 #![feature(box_patterns)]
 #![feature(drain_filter)]
 #![feature(let_chains)]
@@ -69,6 +71,7 @@ pub mod dump_mir;
 mod early_otherwise_branch;
 mod elaborate_box_derefs;
 mod elaborate_drops;
+mod errors;
 mod ffi_unwind_calls;
 mod function_item_references;
 mod generator;
@@ -105,6 +108,11 @@ use rustc_const_eval::transform::promote_consts;
 use rustc_const_eval::transform::validate;
 use rustc_mir_dataflow::rustc_peek;
 
+use rustc_errors::{DiagnosticMessage, SubdiagnosticMessage};
+use rustc_fluent_macro::fluent_messages;
+
+fluent_messages! { "../messages.ftl" }
+
 pub fn provide(providers: &mut Providers) {
     check_unsafety::provide(providers);
     coverage::query::provide(providers);

compiler/rustc_mir_transform/src/lower_intrinsics.rs

@@ -1,6 +1,6 @@
 //! Lowers intrinsic calls
 
-use crate::MirPass;
+use crate::{errors, MirPass};
 use rustc_middle::mir::*;
 use rustc_middle::ty::subst::SubstsRef;
 use rustc_middle::ty::{self, Ty, TyCtxt};
@@ -310,11 +310,7 @@ fn resolve_rust_intrinsic<'tcx>(
 }
 
 fn validate_simd_shuffle<'tcx>(tcx: TyCtxt<'tcx>, args: &[Operand<'tcx>], span: Span) {
-    match &args[2] {
+    if !matches!(args[2], Operand::Constant(_)) {
-        Operand::Constant(_) => {} // all good
+        tcx.sess.emit_err(errors::SimdShuffleLastConst { span });
-        _ => {
-            let msg = "last argument of `simd_shuffle` is required to be a `const` item";
-            tcx.sess.span_err(span, msg);
-        }
     }
 }