resolve: More precise spans for ambiguous resolution errors

Add labels to ambiguous resolution errors

src/librustc_resolve/lib.rs

@@ -1164,8 +1164,7 @@ struct UseError<'a> {
 }
 
 struct AmbiguityError<'a> {
-    span: Span,
-    name: Name,
+    ident: Ident,
     b1: &'a NameBinding<'a>,
     b2: &'a NameBinding<'a>,
 }
@@ -1818,7 +1817,7 @@ impl<'a, 'crateloader: 'a> Resolver<'a, 'crateloader> {
         self.arenas.alloc_module(module)
     }
 
-    fn record_use(&mut self, ident: Ident, ns: Namespace, binding: &'a NameBinding<'a>, span: Span)
+    fn record_use(&mut self, ident: Ident, ns: Namespace, binding: &'a NameBinding<'a>)
                   -> bool /* true if an error was reported */ {
         match binding.kind {
             NameBindingKind::Import { directive, binding, ref used }
@@ -1827,13 +1826,11 @@ impl<'a, 'crateloader: 'a> Resolver<'a, 'crateloader> {
                 directive.used.set(true);
                 self.used_imports.insert((directive.id, ns));
                 self.add_to_glob_map(directive.id, ident);
-                self.record_use(ident, ns, binding, span)
+                self.record_use(ident, ns, binding)
             }
             NameBindingKind::Import { .. } => false,
             NameBindingKind::Ambiguity { b1, b2 } => {
-                self.ambiguity_errors.push(AmbiguityError {
-                    span, name: ident.name, b1, b2,
-                });
+                self.ambiguity_errors.push(AmbiguityError { ident, b1, b2 });
                 true
             }
             _ => false
@@ -2853,7 +2850,7 @@ impl<'a, 'crateloader: 'a> Resolver<'a, 'crateloader> {
                             Def::Const(..) if is_syntactic_ambiguity => {
                                 // Disambiguate in favor of a unit struct/variant
                                 // or constant pattern.
-                                self.record_use(ident, ValueNS, binding.unwrap(), ident.span);
+                                self.record_use(ident, ValueNS, binding.unwrap());
                                 Some(PathResolution::new(def))
                             }
                             Def::StructCtor(..) | Def::VariantCtor(..) |
@@ -4532,12 +4529,12 @@ impl<'a, 'crateloader: 'a> Resolver<'a, 'crateloader> {
         vis.is_accessible_from(module.normal_ancestor_id, self)
     }
 
-    fn report_ambiguity_error(&self, name: Name, span: Span, b1: &NameBinding, b2: &NameBinding) {
+    fn report_ambiguity_error(&self, ident: Ident, b1: &NameBinding, b2: &NameBinding) {
         let participle = |is_import: bool| if is_import { "imported" } else { "defined" };
         let msg1 =
-            format!("`{}` could refer to the name {} here", name, participle(b1.is_import()));
+            format!("`{}` could refer to the name {} here", ident, participle(b1.is_import()));
         let msg2 =
-            format!("`{}` could also refer to the name {} here", name, participle(b2.is_import()));
+            format!("`{}` could also refer to the name {} here", ident, participle(b2.is_import()));
         let note = if b1.expansion != Mark::root() {
             Some(if let Def::Macro(..) = b1.def() {
                 format!("macro-expanded {} do not shadow",
@@ -4547,16 +4544,17 @@ impl<'a, 'crateloader: 'a> Resolver<'a, 'crateloader> {
                         if b1.is_import() { "imports" } else { "items" })
             })
         } else if b1.is_glob_import() {
-            Some(format!("consider adding an explicit import of `{}` to disambiguate", name))
+            Some(format!("consider adding an explicit import of `{}` to disambiguate", ident))
         } else {
             None
         };
 
-        let mut err = struct_span_err!(self.session, span, E0659, "`{}` is ambiguous", name);
+        let mut err = struct_span_err!(self.session, ident.span, E0659, "`{}` is ambiguous", ident);
+        err.span_label(ident.span, "ambiguous name");
         err.span_note(b1.span, &msg1);
         match b2.def() {
             Def::Macro(..) if b2.span.is_dummy() =>
-                err.note(&format!("`{}` is also a builtin macro", name)),
+                err.note(&format!("`{}` is also a builtin macro", ident)),
             _ => err.span_note(b2.span, &msg2),
         };
         if let Some(note) = note {
@@ -4581,9 +4579,9 @@ impl<'a, 'crateloader: 'a> Resolver<'a, 'crateloader> {
             );
         }
 
-        for &AmbiguityError { span, name, b1, b2 } in &self.ambiguity_errors {
-            if reported_spans.insert(span) {
-                self.report_ambiguity_error(name, span, b1, b2);
+        for &AmbiguityError { ident, b1, b2 } in &self.ambiguity_errors {
+            if reported_spans.insert(ident.span) {
+                self.report_ambiguity_error(ident, b1, b2);
             }
         }
 

src/librustc_resolve/macros.rs

@@ -757,8 +757,7 @@ impl<'a, 'cl> Resolver<'a, 'cl> {
                            (innermost_result.0.is_glob_import() ||
                             innermost_result.0.may_appear_after(invoc_id, result.0)) {
                             self.ambiguity_errors.push(AmbiguityError {
-                                span: path_span,
-                                name: ident.name,
+                                ident,
                                 b1: innermost_result.0,
                                 b2: result.0,
                             });
@@ -850,8 +849,7 @@ impl<'a, 'cl> Resolver<'a, 'cl> {
                         if result.def() != innermost_result.def() &&
                            innermost_result.may_appear_after(invoc_id, result) {
                             self.ambiguity_errors.push(AmbiguityError {
-                                span: ident.span,
-                                name: ident.name,
+                                ident,
                                 b1: innermost_result,
                                 b2: result,
                             });
@@ -929,7 +927,7 @@ impl<'a, 'cl> Resolver<'a, 'cl> {
                 (Some(legacy_binding), Ok((binding, FromPrelude(from_prelude))))
                         if !from_prelude || legacy_binding.may_appear_after(invoc_id, binding) => {
                     if legacy_binding.def_ignoring_ambiguity() != binding.def_ignoring_ambiguity() {
-                        self.report_ambiguity_error(ident.name, span, legacy_binding, binding);
+                        self.report_ambiguity_error(ident, legacy_binding, binding);
                     }
                 },
                 // OK, non-macro-expanded legacy wins over prelude even if defs are different
@@ -942,7 +940,7 @@ impl<'a, 'cl> Resolver<'a, 'cl> {
                 (None, Ok((binding, FromPrelude(from_prelude)))) => {
                     check_consistency(self, binding.def_ignoring_ambiguity());
                     if from_prelude {
-                        self.record_use(ident, MacroNS, binding, span);
+                        self.record_use(ident, MacroNS, binding);
                         self.err_if_macro_use_proc_macro(ident.name, span, binding);
                     }
                 }

src/librustc_resolve/resolve_imports.rs

@@ -242,21 +242,19 @@ impl<'a, 'crateloader> Resolver<'a, 'crateloader> {
         if record_used {
             if let Some(binding) = resolution.binding {
                 if let Some(shadowed_glob) = resolution.shadowed_glob {
-                    let name = ident.name;
                     // Forbid expanded shadowing to avoid time travel.
                     if restricted_shadowing &&
                        binding.expansion != Mark::root() &&
                        ns != MacroNS && // In MacroNS, `try_define` always forbids this shadowing
                        binding.def() != shadowed_glob.def() {
                         self.ambiguity_errors.push(AmbiguityError {
-                            span: path_span,
-                            name,
+                            ident,
                             b1: binding,
                             b2: shadowed_glob,
                         });
                     }
                 }
-                if self.record_use(ident, ns, binding, path_span) {
+                if self.record_use(ident, ns, binding) {
                     return Ok(self.dummy_binding);
                 }
                 if !self.is_accessible(binding.vis) {
@@ -936,7 +934,7 @@ impl<'a, 'b:'a, 'c: 'b> ImportResolver<'a, 'b, 'c> {
         self.per_ns(|this, ns| if !type_ns_only || ns == TypeNS {
             if let Ok(binding) = result[ns].get() {
                 all_ns_err = false;
-                if this.record_use(ident, ns, binding, directive.span) {
+                if this.record_use(ident, ns, binding) {
                     if let ModuleOrUniformRoot::Module(module) = module {
                         this.resolution(module, ident, ns).borrow_mut().binding =
                             Some(this.dummy_binding);

src/test/ui/error-codes/E0659.stderr

@@ -1,8 +1,8 @@
 error[E0659]: `foo` is ambiguous
-  --> $DIR/E0659.rs:25:5
+  --> $DIR/E0659.rs:25:15
    |
 LL |     collider::foo(); //~ ERROR E0659
-   |     ^^^^^^^^^^^^^
+   |               ^^^ ambiguous name
    |
 note: `foo` could refer to the name imported here
   --> $DIR/E0659.rs:20:13

src/test/ui/imports/duplicate.stderr

@@ -13,10 +13,10 @@ LL |     use a::foo as other_foo; //~ ERROR the name `foo` is defined multiple t
    |         ^^^^^^^^^^^^^^^^^^^
 
 error[E0659]: `foo` is ambiguous
-  --> $DIR/duplicate.rs:56:9
+  --> $DIR/duplicate.rs:56:15
    |
 LL |     use self::foo::bar; //~ ERROR `foo` is ambiguous
-   |         ^^^^^^^^^^^^^^
+   |               ^^^ ambiguous name
    |
 note: `foo` could refer to the name imported here
   --> $DIR/duplicate.rs:53:9
@@ -31,10 +31,10 @@ LL |     use self::m2::*;
    = note: consider adding an explicit import of `foo` to disambiguate
 
 error[E0659]: `foo` is ambiguous
-  --> $DIR/duplicate.rs:45:5
+  --> $DIR/duplicate.rs:45:8
    |
 LL |     f::foo(); //~ ERROR `foo` is ambiguous
-   |     ^^^^^^
+   |        ^^^ ambiguous name
    |
 note: `foo` could refer to the name imported here
   --> $DIR/duplicate.rs:34:13
@@ -49,10 +49,10 @@ LL |     pub use b::*;
    = note: consider adding an explicit import of `foo` to disambiguate
 
 error[E0659]: `foo` is ambiguous
-  --> $DIR/duplicate.rs:46:5
+  --> $DIR/duplicate.rs:46:8
    |
 LL |     g::foo(); //~ ERROR `foo` is ambiguous
-   |     ^^^^^^
+   |        ^^^ ambiguous name
    |
 note: `foo` could refer to the name imported here
   --> $DIR/duplicate.rs:39:13
@@ -70,7 +70,7 @@ error[E0659]: `foo` is ambiguous
   --> $DIR/duplicate.rs:59:9
    |
 LL |         foo::bar(); //~ ERROR `foo` is ambiguous
-   |         ^^^^^^^^
+   |         ^^^ ambiguous name
    |
 note: `foo` could refer to the name imported here
   --> $DIR/duplicate.rs:53:9

src/test/ui/imports/glob-shadowing.stderr

@@ -2,7 +2,7 @@ error[E0659]: `env` is ambiguous
   --> $DIR/glob-shadowing.rs:21:17
    |
 LL |         let x = env!("PATH"); //~ ERROR `env` is ambiguous
-   |                 ^^^
+   |                 ^^^ ambiguous name
    |
 note: `env` could refer to the name imported here
   --> $DIR/glob-shadowing.rs:19:9
@@ -16,7 +16,7 @@ error[E0659]: `env` is ambiguous
   --> $DIR/glob-shadowing.rs:29:21
    |
 LL |             let x = env!("PATH"); //~ ERROR `env` is ambiguous
-   |                     ^^^
+   |                     ^^^ ambiguous name
    |
 note: `env` could refer to the name imported here
   --> $DIR/glob-shadowing.rs:27:13
@@ -30,7 +30,7 @@ error[E0659]: `fenv` is ambiguous
   --> $DIR/glob-shadowing.rs:39:21
    |
 LL |             let x = fenv!(); //~ ERROR `fenv` is ambiguous
-   |                     ^^^^
+   |                     ^^^^ ambiguous name
    |
 note: `fenv` could refer to the name imported here
   --> $DIR/glob-shadowing.rs:37:13

src/test/ui/imports/issue-53269.stderr

@@ -8,7 +8,7 @@ error[E0659]: `mac` is ambiguous
   --> $DIR/issue-53269.rs:18:5
    |
 LL |     mac!(); //~ ERROR `mac` is ambiguous
-   |     ^^^
+   |     ^^^ ambiguous name
    |
 note: `mac` could refer to the name defined here
   --> $DIR/issue-53269.rs:13:1

src/test/ui/imports/local-modularized-tricky-fail-1.rs

@@ -43,7 +43,6 @@ mod inner2 {
 
 fn main() {
     panic!(); //~ ERROR `panic` is ambiguous
-              //~^ ERROR `panic` is ambiguous
 }
 
 mod inner3 {

src/test/ui/imports/local-modularized-tricky-fail-1.stderr

@@ -2,7 +2,7 @@ error[E0659]: `exported` is ambiguous
   --> $DIR/local-modularized-tricky-fail-1.rs:38:1
    |
 LL | exported!(); //~ ERROR `exported` is ambiguous
-   | ^^^^^^^^
+   | ^^^^^^^^ ambiguous name
    |
 note: `exported` could refer to the name defined here
   --> $DIR/local-modularized-tricky-fail-1.rs:15:5
@@ -22,10 +22,10 @@ LL | use inner1::*;
    = note: macro-expanded macros do not shadow
 
 error[E0659]: `include` is ambiguous
-  --> $DIR/local-modularized-tricky-fail-1.rs:57:1
+  --> $DIR/local-modularized-tricky-fail-1.rs:56:1
    |
 LL | include!(); //~ ERROR `include` is ambiguous
-   | ^^^^^^^
+   | ^^^^^^^ ambiguous name
    |
 note: `include` could refer to the name defined here
   --> $DIR/local-modularized-tricky-fail-1.rs:27:5
@@ -44,7 +44,7 @@ error[E0659]: `panic` is ambiguous
   --> $DIR/local-modularized-tricky-fail-1.rs:45:5
    |
 LL |     panic!(); //~ ERROR `panic` is ambiguous
-   |     ^^^^^
+   |     ^^^^^ ambiguous name
    |
 note: `panic` could refer to the name defined here
   --> $DIR/local-modularized-tricky-fail-1.rs:21:5
@@ -60,10 +60,10 @@ LL |       define_panic!();
    = note: macro-expanded macros do not shadow
 
 error[E0659]: `panic` is ambiguous
-  --> $DIR/local-modularized-tricky-fail-1.rs:45:5
+  --> <panic macros>:1:13
    |
-LL |     panic!(); //~ ERROR `panic` is ambiguous
-   |     ^^^^^^^^^
+LL | (  ) => ( { panic ! ( "explicit panic" ) } ) ; ( $ msg : expr ) => (
+   |             ^^^^^ ambiguous name
    |
 note: `panic` could refer to the name defined here
   --> $DIR/local-modularized-tricky-fail-1.rs:21:5
@@ -77,7 +77,6 @@ LL |       define_panic!();
    |       ---------------- in this macro invocation
    = note: `panic` is also a builtin macro
    = note: macro-expanded macros do not shadow
-   = note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
 
 error: aborting due to 4 previous errors
 

src/test/ui/imports/macro-paths.stderr

@@ -2,7 +2,7 @@ error[E0659]: `bar` is ambiguous
   --> $DIR/macro-paths.rs:23:5
    |
 LL |     bar::m! { //~ ERROR ambiguous
-   |     ^^^^^^
+   |     ^^^ ambiguous name
    |
 note: `bar` could refer to the name defined here
   --> $DIR/macro-paths.rs:24:9
@@ -20,7 +20,7 @@ error[E0659]: `baz` is ambiguous
   --> $DIR/macro-paths.rs:33:5
    |
 LL |     baz::m! { //~ ERROR ambiguous
-   |     ^^^^^^
+   |     ^^^ ambiguous name
    |
 note: `baz` could refer to the name defined here
   --> $DIR/macro-paths.rs:34:9

src/test/ui/imports/macros.stderr

@@ -2,7 +2,7 @@ error[E0659]: `m` is ambiguous
   --> $DIR/macros.rs:48:5
    |
 LL |     m!(); //~ ERROR ambiguous
-   |     ^
+   |     ^ ambiguous name
    |
 note: `m` could refer to the name defined here
   --> $DIR/macros.rs:46:5
@@ -19,7 +19,7 @@ error[E0659]: `m` is ambiguous
   --> $DIR/macros.rs:26:5
    |
 LL |     m! { //~ ERROR ambiguous
-   |     ^
+   |     ^ ambiguous name
    |
 note: `m` could refer to the name imported here
   --> $DIR/macros.rs:27:13
@@ -37,7 +37,7 @@ error[E0659]: `m` is ambiguous
   --> $DIR/macros.rs:39:9
    |
 LL |         m! { //~ ERROR ambiguous
-   |         ^
+   |         ^ ambiguous name
    |
 note: `m` could refer to the name imported here
   --> $DIR/macros.rs:40:17

src/test/ui/imports/rfc-1560-warning-cycle.stderr

@@ -2,7 +2,7 @@ error[E0659]: `Foo` is ambiguous
   --> $DIR/rfc-1560-warning-cycle.rs:19:17
    |
 LL |         fn f(_: Foo) {} //~ ERROR `Foo` is ambiguous
-   |                 ^^^
+   |                 ^^^ ambiguous name
    |
 note: `Foo` could refer to the name imported here
   --> $DIR/rfc-1560-warning-cycle.rs:17:13