Fix: Prevent macro-expanded extern crates from shadowing extern arguments by Delta17920 · Pull Request #149860 · rust-lang/rust (original) (raw)

I think #149855 was actually closer to the right solution than this PR, this PR is just hiding the root issue.

The root issue is that issue_145575_hack swallows legitimate ambiguity errors, it's not surprising that they may result in inconsistent resolutions later.
"inconsistent resolution for an import" ICE is already not reported if ambiguity_errors are non-empty, using dcx().has_errors() would be ok too, even if maybe too blunt.

I guess the most surgical solution would looks something like

diff --git i/compiler/rustc_resolve/src/ident.rs w/compiler/rustc_resolve/src/ident.rs index e38d4370d5d..342c1192090 100644 --- i/compiler/rustc_resolve/src/ident.rs +++ w/compiler/rustc_resolve/src/ident.rs @@ -771,36 +771,38 @@ fn maybe_push_ambiguity( } else { None };

   // Skip ambiguity errors for extern flag bindings "overridden"

```
   // by extern item bindings.
```

   // FIXME: Remove with lang team approval.

   let issue_145575_hack = Some(binding) == extern_prelude_flag_binding

       && extern_prelude_item_binding.is_some()

       && extern_prelude_item_binding != Some(innermost_binding);

   if let Some(kind) = ambiguity_error_kind

```
       && !issue_145575_hack
```
```
   {
```
```
       let misc = |f: Flags| {
```

           if f.contains(Flags::MISC_SUGGEST_CRATE) {

               AmbiguityErrorMisc::SuggestCrate

           } else if f.contains(Flags::MISC_SUGGEST_SELF) {

               AmbiguityErrorMisc::SuggestSelf

           } else if f.contains(Flags::MISC_FROM_PRELUDE) {

               AmbiguityErrorMisc::FromPrelude

```
           } else {
```
```
               AmbiguityErrorMisc::None
```
```
           }
```
```
       };
```

       self.ambiguity_errors.push(AmbiguityError {

```
           kind,
```
```
           ident: orig_ident,
```
```
           b1: innermost_binding,
```
```
           b2: binding,
```
```
           warning: false,
```

           misc1: misc(innermost_flags),

```
           misc2: misc(flags),
```
```
       });
```
```
       return true;
```

   if let Some(kind) = ambiguity_error_kind {

       // Skip ambiguity errors for extern flag bindings "overridden"

```
       // by extern item bindings.
```

       // FIXME: Remove with lang team approval.

       let issue_145575_hack = Some(binding) == extern_prelude_flag_binding

           && extern_prelude_item_binding.is_some()

           && extern_prelude_item_binding != Some(innermost_binding);

```
       if issue_145575_hack {
```

           self.issue_145575_hack_applied = true;

```
       } else {
```
```
           let misc = |f: Flags| {
```

               if f.contains(Flags::MISC_SUGGEST_CRATE) {

                   AmbiguityErrorMisc::SuggestCrate

               } else if f.contains(Flags::MISC_SUGGEST_SELF) {

                   AmbiguityErrorMisc::SuggestSelf

               } else if f.contains(Flags::MISC_FROM_PRELUDE) {

                   AmbiguityErrorMisc::FromPrelude

```
               } else {
```

                   AmbiguityErrorMisc::None

```
               }
```
```
           };
```

           self.ambiguity_errors.push(AmbiguityError {

```
               kind,
```
```
               ident: orig_ident,
```
```
               b1: innermost_binding,
```
```
               b2: binding,
```
```
               warning: false,
```

               misc1: misc(innermost_flags),

```
               misc2: misc(flags),
```
```
           });
```
```
           return true;
```
```
       }
   }

   false
```

diff --git i/compiler/rustc_resolve/src/imports.rs w/compiler/rustc_resolve/src/imports.rs index 4ef87af5605..4e0f3db5982 100644 --- i/compiler/rustc_resolve/src/imports.rs +++ w/compiler/rustc_resolve/src/imports.rs @@ -1170,7 +1170,7 @@ fn finalize_import(&mut self, import: Import<'ra>) -> Option<UnresolvedImportErr return; } if let Some(initial_res) = initial_res {

                       if res != initial_res {

                       if res != initial_res && !this.issue_145575_hack_applied {
                           span_bug!(import.span, "inconsistent resolution for an import");
                       }
                   } else if this.privacy_errors.is_empty() {

diff --git i/compiler/rustc_resolve/src/lib.rs w/compiler/rustc_resolve/src/lib.rs index 8132bf577d8..7e06b8511e3 100644 --- i/compiler/rustc_resolve/src/lib.rs +++ w/compiler/rustc_resolve/src/lib.rs @@ -1186,6 +1186,7 @@ pub struct Resolver<'ra, 'tcx> { privacy_errors: Vec<PrivacyError<'ra>> = Vec::new(), /// Ambiguity errors are delayed for deduplication. ambiguity_errors: Vec<AmbiguityError<'ra>> = Vec::new(),

issue_145575_hack_applied: bool = false, /// use injections are delayed for better placement and deduplication. use_injections: Vec<UseError<'tcx>> = Vec::new(), /// Crate-local macro expanded macro_export referred to by a module-relative path.