Rollup merge of #72789 - petrochenkov:impcand, r=davidtwco

resolve: Do not suggest imports from the same module in which we are resolving

Based on the idea from https://github.com/rust-lang/rust/pull/72623.

src/librustc_resolve/diagnostics.rs

@@ -629,6 +629,7 @@ impl<'a> Resolver<'a> {
         &mut self,
         lookup_ident: Ident,
         namespace: Namespace,
+        parent_scope: &ParentScope<'a>,
         start_module: Module<'a>,
         crate_name: Ident,
         filter_fn: FilterFn,
@@ -655,7 +656,11 @@ impl<'a> Resolver<'a> {
                 }
 
                 // collect results based on the filter function
-                if ident.name == lookup_ident.name && ns == namespace {
+                // avoid suggesting anything from the same module in which we are resolving
+                if ident.name == lookup_ident.name
+                    && ns == namespace
+                    && !ptr::eq(in_module, parent_scope.module)
+                {
                     let res = name_binding.res();
                     if filter_fn(res) {
                         // create the path
@@ -722,6 +727,7 @@ impl<'a> Resolver<'a> {
         &mut self,
         lookup_ident: Ident,
         namespace: Namespace,
+        parent_scope: &ParentScope<'a>,
         filter_fn: FilterFn,
     ) -> Vec<ImportSuggestion>
     where
@@ -730,6 +736,7 @@ impl<'a> Resolver<'a> {
         let mut suggestions = self.lookup_import_candidates_from_module(
             lookup_ident,
             namespace,
+            parent_scope,
             self.graph_root,
             Ident::with_dummy_span(kw::Crate),
             &filter_fn,
@@ -754,6 +761,7 @@ impl<'a> Resolver<'a> {
                     suggestions.extend(self.lookup_import_candidates_from_module(
                         lookup_ident,
                         namespace,
+                        parent_scope,
                         crate_root,
                         ident,
                         &filter_fn,

src/librustc_resolve/late/diagnostics.rs

@@ -212,7 +212,7 @@ impl<'a> LateResolutionVisitor<'a, '_, '_> {
         let ident = path.last().unwrap().ident;
         let candidates = self
             .r
-            .lookup_import_candidates(ident, ns, is_expected)
+            .lookup_import_candidates(ident, ns, &self.parent_scope, is_expected)
             .drain(..)
             .filter(|ImportSuggestion { did, .. }| {
                 match (did, res.and_then(|res| res.opt_def_id())) {
@@ -223,7 +223,8 @@ impl<'a> LateResolutionVisitor<'a, '_, '_> {
             .collect::<Vec<_>>();
         let crate_def_id = DefId::local(CRATE_DEF_INDEX);
         if candidates.is_empty() && is_expected(Res::Def(DefKind::Enum, crate_def_id)) {
-            let enum_candidates = self.r.lookup_import_candidates(ident, ns, is_enum_variant);
+            let enum_candidates =
+                self.r.lookup_import_candidates(ident, ns, &self.parent_scope, is_enum_variant);
             let mut enum_candidates = enum_candidates
                 .iter()
                 .map(|suggestion| import_candidate_to_enum_paths(&suggestion))

src/librustc_resolve/lib.rs

@@ -2235,7 +2235,8 @@ impl<'a> Resolver<'a> {
                             Res::Def(DefKind::Mod, _) => true,
                             _ => false,
                         };
-                        let mut candidates = self.lookup_import_candidates(ident, TypeNS, is_mod);
+                        let mut candidates =
+                            self.lookup_import_candidates(ident, TypeNS, parent_scope, is_mod);
                         candidates.sort_by_cached_key(|c| {
                             (c.path.segments.len(), pprust::path_to_string(&c.path))
                         });

src/test/ui/lexical-scopes.stderr

@@ -3,11 +3,6 @@ error[E0574]: expected struct, variant or union type, found type parameter `T`
    |
 LL |     let t = T { i: 0 };
    |             ^ not a struct, variant or union type
-   |
-help: consider importing this struct instead
-   |
-LL | use T;
-   |
 
 error[E0599]: no function or associated item named `f` found for type parameter `Foo` in the current scope
   --> $DIR/lexical-scopes.rs:10:10

src/test/ui/proc-macro/mixed-site-span.stderr

@@ -27,10 +27,6 @@ LL | pass_dollar_crate!();
    | ^^^^^^^^^^^^^^^^^^^^^ not found in `$crate`
    |
    = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
-help: consider importing this struct
-   |
-LL | use ItemUse;
-   |
 
 error: aborting due to 4 previous errors