resolve: Patch up an inconsistent resolution ICE revealed by the previous commit

Author: petrochenkov

compiler/rustc_resolve/src/ident.rs

@@ -1291,6 +1291,14 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         parent_scope: &ParentScope<'ra>,
     ) -> bool {
         for single_import in &resolution.single_imports {
+            if let Some(binding) = resolution.non_glob_binding
+                && let NameBindingKind::Import { import, .. } = binding.kind
+                && import == *single_import
+            {
+                // Single import has already defined the name and we are aware of it,
+                // no need to block the globs.
+                continue;
+            }
             if ignore_import == Some(*single_import) {
                 continue;
             }

tests/ui/imports/macros.rs

@@ -13,7 +13,7 @@ mod m1 {
 
 mod m2 {
     use two_macros::*;
-    m! {
+    m! { //~ ERROR `m` is ambiguous
         use crate::foo::m;
     }
 }

tests/ui/imports/macros.stderr

@@ -1,3 +1,23 @@
+error[E0659]: `m` is ambiguous
+  --> $DIR/macros.rs:16:5
+   |
+LL |     m! {
+   |     ^ ambiguous name
+   |
+   = note: ambiguous because of a conflict between a macro-expanded name and a less macro-expanded name from outer scope during import or macro resolution
+note: `m` could refer to the macro imported here
+  --> $DIR/macros.rs:17:13
+   |
+LL |         use crate::foo::m;
+   |             ^^^^^^^^^^^^^
+   = help: use `self::m` to refer to this macro unambiguously
+note: `m` could also refer to the macro imported here
+  --> $DIR/macros.rs:15:9
+   |
+LL |     use two_macros::*;
+   |         ^^^^^^^^^^^^^
+   = help: use `self::m` to refer to this macro unambiguously
+
 error[E0659]: `m` is ambiguous
   --> $DIR/macros.rs:29:9
    |
@@ -17,6 +37,6 @@ LL |     use two_macros::m;
    |         ^^^^^^^^^^^^^
    = help: use `self::m` to refer to this macro unambiguously
 
-error: aborting due to 1 previous error
+error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0659`.