Account for hygiene in typo suggestions, and use them to point to shadowed names

compiler/rustc_resolve/src/diagnostics.rs

@@ -24,7 +24,7 @@ use rustc_span::hygiene::MacroKind;
 use rustc_span::lev_distance::find_best_match_for_name;
 use rustc_span::source_map::SourceMap;
 use rustc_span::symbol::{kw, sym, Ident, Symbol};
-use rustc_span::{BytePos, Span};
+use rustc_span::{BytePos, Span, SyntaxContext};
 
 use crate::imports::{Import, ImportKind, ImportResolver};
 use crate::late::{PatternSource, Rib};
@@ -47,13 +47,15 @@ pub(crate) type Suggestion = (Vec<(Span, String)>, String, Applicability);
 /// similarly named label and whether or not it is reachable.
 pub(crate) type LabelSuggestion = (Ident, bool);
 
+#[derive(Debug)]
 pub(crate) enum SuggestionTarget {
     /// The target has a similar name as the name used by the programmer (probably a typo)
     SimilarlyNamed,
     /// The target is the only valid item that can be used in the corresponding context
     SingleItem,
 }
 
+#[derive(Debug)]
 pub(crate) struct TypoSuggestion {
     pub candidate: Symbol,
     pub res: Res,
@@ -482,11 +484,12 @@ impl<'a> Resolver<'a> {
         module: Module<'a>,
         names: &mut Vec<TypoSuggestion>,
         filter_fn: &impl Fn(Res) -> bool,
+        ctxt: Option<SyntaxContext>,
     ) {
         for (key, resolution) in self.resolutions(module).borrow().iter() {
             if let Some(binding) = resolution.borrow().binding {
                 let res = binding.res();
-                if filter_fn(res) {
+                if filter_fn(res) && ctxt.map_or(true, |ctxt| ctxt == key.ident.span.ctxt()) {
                     names.push(TypoSuggestion::typo_from_res(key.ident.name, res));
                 }
             }
@@ -1181,10 +1184,10 @@ impl<'a> Resolver<'a> {
                 Scope::CrateRoot => {
                     let root_ident = Ident::new(kw::PathRoot, ident.span);
                     let root_module = this.resolve_crate_root(root_ident);
-                    this.add_module_candidates(root_module, &mut suggestions, filter_fn);
+                    this.add_module_candidates(root_module, &mut suggestions, filter_fn, None);
                 }
                 Scope::Module(module, _) => {
-                    this.add_module_candidates(module, &mut suggestions, filter_fn);
+                    this.add_module_candidates(module, &mut suggestions, filter_fn, None);
                 }
                 Scope::MacroUsePrelude => {
                     suggestions.extend(this.macro_use_prelude.iter().filter_map(
@@ -1221,7 +1224,7 @@ impl<'a> Resolver<'a> {
                 Scope::StdLibPrelude => {
                     if let Some(prelude) = this.prelude {
                         let mut tmp_suggestions = Vec::new();
-                        this.add_module_candidates(prelude, &mut tmp_suggestions, filter_fn);
+                        this.add_module_candidates(prelude, &mut tmp_suggestions, filter_fn, None);
                         suggestions.extend(
                             tmp_suggestions
                                 .into_iter()

compiler/rustc_resolve/src/late/diagnostics.rs

@@ -131,6 +131,7 @@ pub(super) enum LifetimeElisionCandidate {
 }
 
 /// Only used for diagnostics.
+#[derive(Debug)]
 struct BaseError {
     msg: String,
     fallback_label: String,
@@ -140,6 +141,22 @@ struct BaseError {
     suggestion: Option<(Span, &'static str, String)>,
 }
 
+#[derive(Debug)]
+enum TypoCandidate {
+    Typo(TypoSuggestion),
+    Shadowed(Res),
+    None,
+}
+
+impl TypoCandidate {
+    fn to_opt_suggestion(self) -> Option<TypoSuggestion> {
+        match self {
+            TypoCandidate::Typo(sugg) => Some(sugg),
+            TypoCandidate::Shadowed(_) | TypoCandidate::None => None,
+        }
+    }
+}
+
 impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
     fn def_span(&self, def_id: DefId) -> Option<Span> {
         match def_id.krate {
@@ -496,7 +513,8 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
         }
 
         // Try Levenshtein algorithm.
-        let typo_sugg = self.lookup_typo_candidate(path, source.namespace(), is_expected);
+        let typo_sugg =
+            self.lookup_typo_candidate(path, source.namespace(), is_expected).to_opt_suggestion();
         if path.len() == 1 && self.self_type_is_available() {
             if let Some(candidate) = self.lookup_assoc_candidate(ident, ns, is_expected) {
                 let self_is_available = self.self_value_is_available(path[0].ident.span);
@@ -660,7 +678,18 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
         let is_expected = &|res| source.is_expected(res);
         let ident_span = path.last().map_or(span, |ident| ident.ident.span);
         let typo_sugg = self.lookup_typo_candidate(path, source.namespace(), is_expected);
+        if let TypoCandidate::Shadowed(res) = typo_sugg
+            && let Some(id) = res.opt_def_id()
+            && let Some(sugg_span) = self.r.opt_span(id)
+        {
+            err.span_label(
+                sugg_span,
+                format!("you might have meant to refer to this {}", res.descr()),
+            );
+            return true;
+        }
         let mut fallback = false;
+        let typo_sugg = typo_sugg.to_opt_suggestion();
         if !self.r.add_typo_suggestion(err, typo_sugg, ident_span) {
             fallback = true;
             match self.diagnostic_metadata.current_let_binding {
@@ -1581,22 +1610,38 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
         path: &[Segment],
         ns: Namespace,
         filter_fn: &impl Fn(Res) -> bool,
-    ) -> Option<TypoSuggestion> {
+    ) -> TypoCandidate {
         let mut names = Vec::new();
         if path.len() == 1 {
+            let mut ctxt = path.last().unwrap().ident.span.ctxt();
+
             // Search in lexical scope.
             // Walk backwards up the ribs in scope and collect candidates.
             for rib in self.ribs[ns].iter().rev() {
+                let rib_ctxt = if rib.kind.contains_params() {
+                    ctxt.normalize_to_macros_2_0()
+                } else {
+                    ctxt.normalize_to_macro_rules()
+                };
+
                 // Locals and type parameters
                 for (ident, &res) in &rib.bindings {
-                    if filter_fn(res) {
+                    if filter_fn(res) && ident.span.ctxt() == rib_ctxt {
                         names.push(TypoSuggestion::typo_from_res(ident.name, res));
                     }
                 }
+
+                if let RibKind::MacroDefinition(def) = rib.kind && def == self.r.macro_def(ctxt) {
+                    // If an invocation of this macro created `ident`, give up on `ident`
+                    // and switch to `ident`'s source from the macro definition.
+                    ctxt.remove_mark();
+                    continue;
+                }
+
                 // Items in scope
                 if let RibKind::ModuleRibKind(module) = rib.kind {
                     // Items from this module
-                    self.r.add_module_candidates(module, &mut names, &filter_fn);
+                    self.r.add_module_candidates(module, &mut names, &filter_fn, Some(ctxt));
 
                     if let ModuleKind::Block = module.kind {
                         // We can see through blocks
@@ -1622,7 +1667,7 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
                             }));
 
                             if let Some(prelude) = self.r.prelude {
-                                self.r.add_module_candidates(prelude, &mut names, &filter_fn);
+                                self.r.add_module_candidates(prelude, &mut names, &filter_fn, None);
                             }
                         }
                         break;
@@ -1641,7 +1686,7 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
             if let PathResult::Module(ModuleOrUniformRoot::Module(module)) =
                 self.resolve_path(mod_path, Some(TypeNS), None)
             {
-                self.r.add_module_candidates(module, &mut names, &filter_fn);
+                self.r.add_module_candidates(module, &mut names, &filter_fn, None);
             }
         }
 
@@ -1654,10 +1699,17 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
             name,
             None,
         ) {
-            Some(found) if found != name => {
-                names.into_iter().find(|suggestion| suggestion.candidate == found)
+            Some(found) => {
+                let Some(sugg) = names.into_iter().find(|suggestion| suggestion.candidate == found) else {
+                    return TypoCandidate::None;
+                };
+                if found == name {
+                    TypoCandidate::Shadowed(sugg.res)
+                } else {
+                    TypoCandidate::Typo(sugg)
+                }
             }
-            _ => None,
+            _ => TypoCandidate::None,
         }
     }
 

src/test/ui/hygiene/globs.stderr

@@ -1,9 +1,16 @@
 error[E0425]: cannot find function `f` in this scope
   --> $DIR/globs.rs:22:9
    |
+LL |     pub fn g() {}
+   |     ---------- similarly named function `g` defined here
+...
 LL |         f();
-   |         ^ not found in this scope
+   |         ^
+   |
+help: a function with a similar name exists
    |
+LL |         g();
+   |         ~
 help: consider importing this function
    |
 LL | use foo::f;
@@ -12,8 +19,11 @@ LL | use foo::f;
 error[E0425]: cannot find function `g` in this scope
   --> $DIR/globs.rs:15:5
    |
+LL |       pub fn f() {}
+   |       ---------- similarly named function `f` defined here
+...
 LL |       g();
-   |       ^ not found in this scope
+   |       ^
 ...
 LL | /     m! {
 LL | |         use bar::*;
@@ -23,6 +33,10 @@ LL | |     }
    | |_____- in this macro invocation
    |
    = note: this error originates in the macro `m` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: a function with a similar name exists
+   |
+LL |     f();
+   |     ~
 help: consider importing this function
    |
 LL | use bar::g;

src/test/ui/hygiene/rustc-macro-transparency.stderr

@@ -19,14 +19,8 @@ LL |     semitransparent;
 error[E0423]: expected value, found macro `opaque`
   --> $DIR/rustc-macro-transparency.rs:30:5
    |
-LL |     struct Opaque;
-   |     -------------- similarly named unit struct `Opaque` defined here
-...
 LL |     opaque;
-   |     ^^^^^^
-   |     |
-   |     not a value
-   |     help: a unit struct with a similar name exists (notice the capitalization): `Opaque`
+   |     ^^^^^^ not a value
 
 error: aborting due to 3 previous errors
 

src/test/ui/lexical-scopes.stderr

@@ -1,6 +1,8 @@
 error[E0574]: expected struct, variant or union type, found type parameter `T`
   --> $DIR/lexical-scopes.rs:3:13
    |
+LL | struct T { i: i32 }
+   | ------------------- you might have meant to refer to this struct
 LL | fn f<T>() {
    |      - found this type parameter
 LL |     let t = T { i: 0 };

src/test/ui/macros/macro-context.stderr

@@ -57,7 +57,7 @@ error[E0425]: cannot find value `i` in this scope
   --> $DIR/macro-context.rs:3:13
    |
 LL |     () => ( i ; typeof );
-   |             ^ help: a local variable with a similar name exists: `a`
+   |             ^ not found in this scope
 ...
 LL |     let i = m!();
    |             ---- in this macro invocation

src/test/ui/proc-macro/gen-macro-rules-hygiene.stderr

@@ -13,7 +13,7 @@ error[E0425]: cannot find value `local_use` in this scope
   --> $DIR/gen-macro-rules-hygiene.rs:12:1
    |
 LL | gen_macro_rules!();
-   | ^^^^^^^^^^^^^^^^^^ not found in this scope
+   | ^^^^^^^^^^^^^^^^^^ help: a local variable with a similar name exists: `local_def`
 ...
 LL |         generated!();
    |         ------------ in this macro invocation
@@ -24,7 +24,7 @@ error[E0425]: cannot find value `local_def` in this scope
   --> $DIR/gen-macro-rules-hygiene.rs:21:9
    |
 LL |         local_def;
-   |         ^^^^^^^^^ not found in this scope
+   |         ^^^^^^^^^ help: a local variable with a similar name exists: `local_use`
 
 error: aborting due to 3 previous errors
 

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

@@ -10,15 +10,15 @@ error[E0425]: cannot find value `local_use` in this scope
   --> $DIR/mixed-site-span.rs:13:9
    |
 LL |         proc_macro_rules!();
-   |         ^^^^^^^^^^^^^^^^^^^ not found in this scope
+   |         ^^^^^^^^^^^^^^^^^^^ help: a local variable with a similar name exists: `local_def`
    |
    = note: this error originates in the macro `proc_macro_rules` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0425]: cannot find value `local_def` in this scope
   --> $DIR/mixed-site-span.rs:17:9
    |
 LL |         local_def;
-   |         ^^^^^^^^^ not found in this scope
+   |         ^^^^^^^^^ help: a local variable with a similar name exists: `local_use`
 
 error[E0412]: cannot find type `ItemUse` in crate `$crate`
   --> $DIR/mixed-site-span.rs:24:1

src/test/ui/resolve/point-at-type-parameter-shadowing-another-type.stderr

@@ -1,11 +1,16 @@
 error[E0574]: expected struct, variant or union type, found type parameter `Baz`
   --> $DIR/point-at-type-parameter-shadowing-another-type.rs:16:13
    |
-LL | impl<Baz> Foo<Baz> for Bar {
-   |      --- found this type parameter
+LL | / struct Baz {
+LL | |     num: usize,
+LL | | }
+   | |_- you might have meant to refer to this struct
+LL |
+LL |   impl<Baz> Foo<Baz> for Bar {
+   |        --- found this type parameter
 ...
-LL |             Baz { num } => num,
-   |             ^^^ not a struct, variant or union type
+LL |               Baz { num } => num,
+   |               ^^^ not a struct, variant or union type
 
 error: aborting due to previous error