resolver diagnostics: don't swallow labels and point out similar items as a note, not a label

compiler/rustc_resolve/src/diagnostics/impls.rs

@@ -1928,9 +1928,8 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             ident,
             is_expected,
         );
-        if !self.add_typo_suggestion(err, suggestion, ident.span) {
-            self.detect_derive_attribute(err, ident, parent_scope, sugg_span);
-        }
+        self.add_typo_suggestion(err, suggestion, ident.span);
+        self.detect_derive_attribute(err, ident, parent_scope, sugg_span);
 
         let import_suggestions =
             self.lookup_import_candidates(ident, Namespace::MacroNS, parent_scope, is_expected);
@@ -2211,11 +2210,11 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         err: &mut Diag<'_>,
         suggestion: Option<TypoSuggestion>,
         span: Span,
-    ) -> bool {
+    ) {
         let suggestion = match suggestion {
-            None => return false,
+            None => return,
             // We shouldn't suggest underscore.
-            Some(suggestion) if suggestion.candidate == kw::Underscore => return false,
+            Some(suggestion) if suggestion.candidate == kw::Underscore => return,
             Some(suggestion) => suggestion,
         };
 
@@ -2241,7 +2240,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                 //    |
                 // LL | const Y: X = Y("ö");
                 //    |              ^
-                return false;
+                return;
             }
             let span = self.tcx.sess.source_map().guess_head_span(def_span);
             let candidate_descr = suggestion.res.descr();
@@ -2271,7 +2270,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                 "the leading underscore in `{candidate}` marks it as unused, consider renaming it to `{snippet}`"
             );
             if !did_label_def_span {
-                err.span_label(span, format!("`{candidate}` defined here"));
+                err.span_note(span, format!("`{candidate}` defined here"));
             }
             (span, msg, snippet)
         } else {
@@ -2288,7 +2287,6 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             (span, msg, suggestion.candidate.to_ident_string())
         };
         err.span_suggestion_verbose(span, msg, sugg, Applicability::MaybeIncorrect);
-        true
     }
 
     fn decl_description(&self, b: Decl<'_>, ident: Ident, scope: Scope<'_>) -> String {

compiler/rustc_resolve/src/diagnostics/mod.rs

@@ -1219,14 +1219,14 @@ pub(crate) struct CannotFindBuiltinMacroWithName {
 
 #[derive(Subdiagnostic)]
 pub(crate) enum DefinedHere {
-    #[label("similarly named {$candidate_descr} `{$candidate}` defined here")]
+    #[note("similarly named {$candidate_descr} `{$candidate}` defined here")]
     SimilarlyNamed {
         #[primary_span]
         span: Span,
         candidate_descr: &'static str,
         candidate: Symbol,
     },
-    #[label("{$candidate_descr} `{$candidate}` defined here")]
+    #[note("{$candidate_descr} `{$candidate}` defined here")]
     SingleItem {
         #[primary_span]
         span: Span,

compiler/rustc_resolve/src/late/diagnostics.rs

@@ -1319,31 +1319,30 @@ impl<'ast, 'ra, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
 
         let typo_sugg =
             self.lookup_typo_candidate(path, following_seg, source.namespace(), is_expected);
-        let mut fallback = false;
+        let mut fallback = true;
         let typo_sugg = typo_sugg
             .to_opt_suggestion()
             .filter(|sugg| !suggested_candidates.contains(sugg.candidate.as_str()));
-        if !self.r.add_typo_suggestion(err, typo_sugg, ident_span) {
-            fallback = true;
-            match self.diag_metadata.current_let_binding {
-                Some((pat_sp, Some(ty_sp), None))
-                    if ty_sp.contains(base_error.span) && base_error.could_be_expr =>
-                {
-                    err.span_suggestion_verbose(
-                        pat_sp.between(ty_sp),
-                        "use `=` if you meant to assign",
-                        " = ",
-                        Applicability::MaybeIncorrect,
-                    );
-                }
-                _ => {}
-            }
+        self.r.add_typo_suggestion(err, typo_sugg, ident_span);
 
-            // If the trait has a single item (which wasn't matched by the algorithm), suggest it
-            let suggestion = self.get_single_associated_item(path, &source, is_expected);
-            self.r.add_typo_suggestion(err, suggestion, ident_span);
+        match self.diag_metadata.current_let_binding {
+            Some((pat_sp, Some(ty_sp), None))
+                if ty_sp.contains(base_error.span) && base_error.could_be_expr =>
+            {
+                err.span_suggestion_verbose(
+                    pat_sp.between(ty_sp),
+                    "use `=` if you meant to assign",
+                    " = ",
+                    Applicability::MaybeIncorrect,
+                );
+            }
+            _ => {}
         }
 
+        // If the trait has a single item (which wasn't matched by the algorithm), suggest it
+        let suggestion = self.get_single_associated_item(path, &source, is_expected);
+        self.r.add_typo_suggestion(err, suggestion, ident_span);
+
         if self.let_binding_suggestion(err, ident_span) {
             fallback = false;
         }

tests/ui-fulldeps/session-diagnostic/diagnostic-derive-inline.stderr

@@ -541,6 +541,11 @@ help: a built-in attribute with a similar name exists
 LL - #[lint("this is an example message", code = E0123)]
 LL + #[link("this is an example message", code = E0123)]
    |
+help: the derive macros `Lift` and `Lift_Generic` accept the similarly named `lift` attribute
+   |
+LL - #[lint("this is an example message", code = E0123)]
+LL + #[lift("this is an example message", code = E0123)]
+   |
 
 error: cannot find attribute `multipart_suggestion` in this scope
   --> $DIR/diagnostic-derive-inline.rs:565:3

tests/ui/argument-suggestions/disjoint-spans-issue-151607.stderr

@@ -1,12 +1,14 @@
 error[E0425]: cannot find type `E` in this scope
   --> $DIR/disjoint-spans-issue-151607.rs:8:24
    |
-LL | struct B;
-   | --------- similarly named struct `B` defined here
-...
 LL | fn foo(g: F, y: F, e: &E) {
-   |                        ^
+   |                        ^ not found in this scope
+   |
+note: similarly named struct `B` defined here
+  --> $DIR/disjoint-spans-issue-151607.rs:5:1
    |
+LL | struct B;
+   | ^^^^^^^^^
 help: a struct with a similar name exists
    |
 LL - fn foo(g: F, y: F, e: &E) {
@@ -21,7 +23,7 @@ error[E0425]: cannot find value `E` in this scope
   --> $DIR/disjoint-spans-issue-151607.rs:10:18
    |
 LL |     foo(B, g, D, E, F, G)
-   |                  ^
+   |                  ^ not found in this scope
    |
 help: a local variable with a similar name exists
    |
@@ -43,7 +45,7 @@ error[E0425]: cannot find value `G` in this scope
   --> $DIR/disjoint-spans-issue-151607.rs:10:24
    |
 LL |     foo(B, g, D, E, F, G)
-   |                        ^
+   |                        ^ not found in this scope
    |
 help: a local variable with a similar name exists
    |

tests/ui/argument-suggestions/issue-109831.stderr

@@ -1,12 +1,14 @@
 error[E0425]: cannot find type `C` in this scope
   --> $DIR/issue-109831.rs:4:24
    |
-LL | struct A;
-   | --------- similarly named struct `A` defined here
-...
 LL | fn f(b1: B, b2: B, a2: C) {}
-   |                        ^
+   |                        ^ not found in this scope
+   |
+note: similarly named struct `A` defined here
+  --> $DIR/issue-109831.rs:1:1
    |
+LL | struct A;
+   | ^^^^^^^^^
 help: a struct with a similar name exists
    |
 LL - fn f(b1: B, b2: B, a2: C) {}
@@ -20,12 +22,14 @@ LL | fn f<C>(b1: B, b2: B, a2: C) {}
 error[E0425]: cannot find value `C` in this scope
   --> $DIR/issue-109831.rs:7:16
    |
-LL | struct A;
-   | --------- similarly named unit struct `A` defined here
-...
 LL |     f(A, A, B, C);
-   |                ^
+   |                ^ not found in this scope
+   |
+note: similarly named unit struct `A` defined here
+  --> $DIR/issue-109831.rs:1:1
    |
+LL | struct A;
+   | ^^^^^^^^^
 help: a unit struct with a similar name exists
    |
 LL -     f(A, A, B, C);

tests/ui/associated-item/issue-87638.stderr

@@ -1,12 +1,14 @@
 error[E0576]: cannot find associated type `Output` in trait `Trait`
   --> $DIR/issue-87638.rs:17:26
    |
-LL |     type Target;
-   |     ------------ associated type `Target` defined here
-...
 LL |     let _: <S as Trait>::Output;
    |                          ^^^^^^ not found in `Trait`
    |
+note: associated type `Target` defined here
+  --> $DIR/issue-87638.rs:6:5
+   |
+LL |     type Target;
+   |     ^^^^^^^^^^^^
 help: maybe you meant this associated type
    |
 LL -     let _: <S as Trait>::Output;
@@ -16,12 +18,14 @@ LL +     let _: <S as Trait>::Target;
 error[E0576]: cannot find method or associated constant `BAR` in trait `Trait`
   --> $DIR/issue-87638.rs:20:27
    |
-LL |     const FOO: usize;
-   |     ----------------- associated constant `FOO` defined here
-...
 LL |     let _ = <S as Trait>::BAR;
    |                           ^^^ not found in `Trait`
    |
+note: associated constant `FOO` defined here
+  --> $DIR/issue-87638.rs:4:5
+   |
+LL |     const FOO: usize;
+   |     ^^^^^^^^^^^^^^^^^
 help: maybe you meant this associated constant
    |
 LL -     let _ = <S as Trait>::BAR;

tests/ui/associated-types/issue-19883.stderr

@@ -1,12 +1,14 @@
 error[E0576]: cannot find associated type `Dst` in trait `From`
   --> $DIR/issue-19883.rs:9:30
    |
-LL |     type Output;
-   |     ------------ associated type `Output` defined here
-...
 LL |         <Dst as From<Self>>::Dst
    |                              ^^^ not found in `From`
    |
+note: associated type `Output` defined here
+  --> $DIR/issue-19883.rs:2:5
+   |
+LL |     type Output;
+   |     ^^^^^^^^^^^^
 help: maybe you meant this associated type
    |
 LL -         <Dst as From<Self>>::Dst

tests/ui/associated-types/issue-22037.stderr

@@ -1,11 +1,14 @@
 error[E0576]: cannot find associated type `X` in trait `A`
   --> $DIR/issue-22037.rs:3:33
    |
-LL |     type Output;
-   |     ------------ associated type `Output` defined here
 LL |     fn a(&self) -> <Self as A>::X;
    |                                 ^ not found in `A`
    |
+note: associated type `Output` defined here
+  --> $DIR/issue-22037.rs:2:5
+   |
+LL |     type Output;
+   |     ^^^^^^^^^^^^
 help: maybe you meant this associated type
    |
 LL -     fn a(&self) -> <Self as A>::X;

tests/ui/attributes/align-on-fields-143987.stderr

@@ -2,7 +2,7 @@ error[E0425]: cannot find type `usize8` in this scope
   --> $DIR/align-on-fields-143987.rs:17:8
    |
 LL |     x: usize8,
-   |        ^^^^^^
+   |        ^^^^^^ not found in this scope
    |
 help: a builtin type with a similar name exists
    |

tests/ui/c-variadic/issue-86053-1.stderr

@@ -58,11 +58,10 @@ error[E0425]: cannot find type `F` in this scope
   --> $DIR/issue-86053-1.rs:10:54
    |
 LL |     self , _: ... ,   self ,   self , _: ... ) where F : FnOnce ( & 'a & 'b usize ) {
-   |                                                      ^
+   |                                                      ^ not found in this scope
    |
+note: similarly named trait `Fn` defined here
   --> $SRC_DIR/core/src/ops/function.rs:LL:COL
-   |
-   = note: similarly named trait `Fn` defined here
 help: a trait with a similar name exists
    |
 LL |     self , _: ... ,   self ,   self , _: ... ) where Fn : FnOnce ( & 'a & 'b usize ) {

tests/ui/closures/issue-78720.stderr

@@ -8,11 +8,10 @@ error[E0425]: cannot find type `F` in this scope
   --> $DIR/issue-78720.rs:14:12
    |
 LL |     _func: F,
-   |            ^
+   |            ^ not found in this scope
    |
+note: similarly named trait `Fn` defined here
   --> $SRC_DIR/core/src/ops/function.rs:LL:COL
-   |
-   = note: similarly named trait `Fn` defined here
 help: a trait with a similar name exists
    |
 LL |     _func: Fn,

tests/ui/closures/issue-90871.stderr

@@ -2,11 +2,10 @@ error[E0425]: cannot find type `n` in this scope
   --> $DIR/issue-90871.rs:4:22
    |
 LL |     type_ascribe!(2, n([u8; || 1]))
-   |                      ^
+   |                      ^ not found in this scope
    |
+note: similarly named trait `Fn` defined here
   --> $SRC_DIR/core/src/ops/function.rs:LL:COL
-   |
-   = note: similarly named trait `Fn` defined here
 help: a trait with a similar name exists
    |
 LL |     type_ascribe!(2, Fn([u8; || 1]))

tests/ui/cmse-nonsecure/cmse-nonsecure-call/generics.stderr

@@ -7,11 +7,14 @@ LL |     f1: extern "cmse-nonsecure-call" fn<U: Copy>(U, u32, u32, u32) -> u64,
 error[E0425]: cannot find type `U` in this scope
   --> $DIR/generics.rs:15:50
    |
-LL | struct Test<T: Copy> {
-   |             - similarly named type parameter `T` defined here
 LL |     f1: extern "cmse-nonsecure-call" fn<U: Copy>(U, u32, u32, u32) -> u64,
-   |                                                  ^
+   |                                                  ^ not found in this scope
+   |
+note: similarly named type parameter `T` defined here
+  --> $DIR/generics.rs:14:13
    |
+LL | struct Test<T: Copy> {
+   |             ^
 help: a type parameter with a similar name exists
    |
 LL -     f1: extern "cmse-nonsecure-call" fn<U: Copy>(U, u32, u32, u32) -> u64,

tests/ui/compiletest-self-test/ui-testing-optout.stderr

@@ -7,12 +7,14 @@ error[E0425]: cannot find type `B` in this scope
 error[E0425]: cannot find type `D` in this scope
  --> $DIR/ui-testing-optout.rs:7:10
   |
-4 | type A = B;
-  | ----------- similarly named type alias `A` defined here
-...
 7 | type C = D;
-  |          ^
+  |          ^ not found in this scope
   |
+note: similarly named type alias `A` defined here
+ --> $DIR/ui-testing-optout.rs:4:1
+  |
+4 | type A = B;
+  | ^^^^^^^^^^^
 help: a type alias with a similar name exists
   |
 7 - type C = D;
@@ -22,12 +24,14 @@ help: a type alias with a similar name exists
 error[E0425]: cannot find type `F` in this scope
   --> $DIR/ui-testing-optout.rs:92:10
    |
- 4 | type A = B;
-   | ----------- similarly named type alias `A` defined here
-...
 92 | type E = F;
-   |          ^
+   |          ^ not found in this scope
+   |
+note: similarly named type alias `A` defined here
+  --> $DIR/ui-testing-optout.rs:4:1
    |
+ 4 | type A = B;
+   | ^^^^^^^^^^^
 help: a type alias with a similar name exists
    |
 92 - type E = F;