resolve: Fix ICE in macro import error recovery

Author: petrochenkov

src/librustc_resolve/macros.rs

@@ -449,6 +449,9 @@ impl<'a, 'cl> Resolver<'a, 'cl> {
                     return Err(Determinacy::Determined);
                 }
             }
+            Def::Err => {
+                return Err(Determinacy::Determined);
+            }
             _ => panic!("expected `Def::Macro` or `Def::NonMacroAttr`"),
         }
 

src/test/ui/imports/issue-55457.rs

@@ -0,0 +1,8 @@
+use NonExistent; //~ ERROR unresolved import `NonExistent`
+use non_existent::non_existent; //~ ERROR unresolved import `non_existent`
+
+#[non_existent] //~ ERROR cannot determine resolution for the attribute macro `non_existent`
+#[derive(NonExistent)] //~ ERROR cannot determine resolution for the derive macro `NonExistent`
+struct S;
+
+fn main() {}

src/test/ui/imports/issue-55457.stderr

@@ -0,0 +1,31 @@
+error[E0432]: unresolved import `NonExistent`
+  --> $DIR/issue-55457.rs:1:5
+   |
+LL | use NonExistent; //~ ERROR unresolved import `NonExistent`
+   |     ^^^^^^^^^^^ no `NonExistent` in the root. Did you mean to use `non_existent`?
+
+error[E0432]: unresolved import `non_existent`
+  --> $DIR/issue-55457.rs:2:5
+   |
+LL | use non_existent::non_existent; //~ ERROR unresolved import `non_existent`
+   |     ^^^^^^^^^^^^ Maybe a missing `extern crate non_existent;`?
+
+error: cannot determine resolution for the derive macro `NonExistent`
+  --> $DIR/issue-55457.rs:5:10
+   |
+LL | #[derive(NonExistent)] //~ ERROR cannot determine resolution for the derive macro `NonExistent`
+   |          ^^^^^^^^^^^
+   |
+   = note: import resolution is stuck, try simplifying macro imports
+
+error: cannot determine resolution for the attribute macro `non_existent`
+  --> $DIR/issue-55457.rs:4:3
+   |
+LL | #[non_existent] //~ ERROR cannot determine resolution for the attribute macro `non_existent`
+   |   ^^^^^^^^^^^^
+   |
+   = note: import resolution is stuck, try simplifying macro imports
+
+error: aborting due to 4 previous errors
+
+For more information about this error, try `rustc --explain E0432`.