Add AmbiguityError for inconsistent resolution for an import

compiler/rustc_resolve/src/imports.rs

@@ -4,7 +4,10 @@ use crate::diagnostics::{import_candidates, Suggestion};
 use crate::Determinacy::{self, *};
 use crate::Namespace::*;
 use crate::{module_to_string, names_to_string, ImportSuggestion};
-use crate::{AmbiguityKind, BindingKey, ModuleKind, ResolutionError, Resolver, Segment};
+use crate::{
+    AmbiguityError, AmbiguityErrorMisc, AmbiguityKind, BindingKey, ModuleKind, ResolutionError,
+    Resolver, Segment,
+};
 use crate::{Finalize, Module, ModuleOrUniformRoot, ParentScope, PerNS, ScopeSet};
 use crate::{NameBinding, NameBindingKind, PathResult};
 
@@ -791,7 +794,7 @@ impl<'a, 'b> ImportResolver<'a, 'b> {
                 match binding {
                     Ok(binding) => {
                         // Consistency checks, analogous to `finalize_macro_resolutions`.
-                        let initial_res = source_bindings[ns].get().map(|initial_binding| {
+                        let initial_binding = source_bindings[ns].get().map(|initial_binding| {
                             all_ns_err = false;
                             if let Some(target_binding) = target_bindings[ns].get() {
                                 if target.name == kw::Underscore
@@ -805,12 +808,20 @@ impl<'a, 'b> ImportResolver<'a, 'b> {
                                     );
                                 }
                             }
-                            initial_binding.res()
+                            initial_binding
                         });
                         let res = binding.res();
-                        if let Ok(initial_res) = initial_res {
+                        if let Ok(initial_binding) = initial_binding {
+                            let initial_res = initial_binding.res();
                             if res != initial_res && this.ambiguity_errors.is_empty() {
-                                span_bug!(import.span, "inconsistent resolution for an import");
+                                this.ambiguity_errors.push(AmbiguityError {
+                                    kind: AmbiguityKind::Import,
+                                    ident,
+                                    b1: initial_binding,
+                                    b2: binding,
+                                    misc1: AmbiguityErrorMisc::None,
+                                    misc2: AmbiguityErrorMisc::None,
+                                });
                             }
                         } else if res != Res::Err
                             && this.ambiguity_errors.is_empty()

src/test/ui/resolve/issue-105069.rs

@@ -0,0 +1,11 @@
+use self::A::*;
+use V; //~ ERROR `V` is ambiguous
+use self::B::*;
+enum A {
+    V
+}
+enum B {
+    V
+}
+
+fn main() {}

src/test/ui/resolve/issue-105069.stderr

@@ -0,0 +1,21 @@
+error[E0659]: `V` is ambiguous
+  --> $DIR/issue-105069.rs:2:5
+   |
+LL | use V;
+   |     ^ ambiguous name
+   |
+   = note: ambiguous because of multiple potential import sources
+note: `V` could refer to the variant imported here
+  --> $DIR/issue-105069.rs:1:5
+   |
+LL | use self::A::*;
+   |     ^^^^^^^^^^
+note: `V` could also refer to the variant imported here
+  --> $DIR/issue-105069.rs:3:5
+   |
+LL | use self::B::*;
+   |     ^^^^^^^^^^
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0659`.