resolve: Reduce some clutter in import ambiguity errors

Author: petrochenkov

src/librustc_resolve/resolve_imports.rs

@@ -843,14 +843,16 @@ impl<'a, 'b:'a, 'c: 'b> ImportResolver<'a, 'b, 'c> {
  self.current_module = directive.parent_scope.module;
 
  let orig_vis = directive.vis.replace(ty::Visibility::Invisible);
+ let prev_ambiguity_errors_len = self.ambiguity_errors.len();
  let path_res = self.resolve_path(&directive.module_path, None, &directive.parent_scope,
  true, directive.span, directive.crate_lint());
+ let no_ambiguity = self.ambiguity_errors.len() == prev_ambiguity_errors_len;
  directive.vis.set(orig_vis);
  let module = match path_res {
  PathResult::Module(module) => {
  // Consistency checks, analogous to `finalize_current_module_macro_resolutions`.
  if let Some(initial_module) = directive.imported_module.get() {
- if module != initial_module && self.ambiguity_errors.is_empty() {
+ if module != initial_module && no_ambiguity {
  span_bug!(directive.span, "inconsistent resolution for an import");
  }
  } else {
@@ -864,30 +866,32 @@ impl<'a, 'b:'a, 'c: 'b> ImportResolver<'a, 'b, 'c> {
  module
  }
  PathResult::Failed(span, msg, false) => {
- assert!(!self.ambiguity_errors.is_empty() ||
- directive.imported_module.get().is_none());
- resolve_error(self, span, ResolutionError::FailedToResolve(&msg));
+ if no_ambiguity {
+ assert!(directive.imported_module.get().is_none());
+ resolve_error(self, span, ResolutionError::FailedToResolve(&msg));
+ }
  return None;
  }
  PathResult::Failed(span, msg, true) => {
- assert!(!self.ambiguity_errors.is_empty() ||
-  directive.imported_module.get().is_none());
- return if let Some((suggested_path, note)) = self.make_path_suggestion(
- span, directive.module_path.clone(), &directive.parent_scope
- ) {
- Some((
- span,
- format!("did you mean `{}`?", Segment::names_to_string(&suggested_path)),
- note,
- ))
- } else {
-  Some((span, msg, None))
- };
+ if no_ambiguity {
+ assert!(directive.imported_module.get().is_none());
+  return Some(match self.make_path_suggestion(span, directive.module_path.clone(),
+  &directive.parent_scope) {
+  Some((suggestion, note)) => (
+  span,
+  format!("did you mean `{}`?", Segment::names_to_string(&suggestion)),
+  note,
+ ),
+  None => (span, msg, None),
+  });
+ }
+ return None;
  }
  PathResult::NonModule(path_res) if path_res.base_def() == Def::Err => {
+ if no_ambiguity {
+ assert!(directive.imported_module.get().is_none());
+ }
  // The error was already reported earlier.
- assert!(!self.ambiguity_errors.is_empty() ||
- directive.imported_module.get().is_none());
  return None;
  }
  PathResult::Indeterminate | PathResult::NonModule(..) => unreachable!(),

src/test/ui/imports/issue-56125.rs

@@ -7,13 +7,11 @@
 mod m1 {
  use issue_56125::last_segment::*;
  //~^ ERROR `issue_56125` is ambiguous
- //~| ERROR unresolved import `issue_56125::last_segment`
 }
 
 mod m2 {
  use issue_56125::non_last_segment::non_last_segment::*;
  //~^ ERROR `issue_56125` is ambiguous
- //~| ERROR failed to resolve: could not find `non_last_segment` in `issue_56125`
 }
 
 mod m3 {

src/test/ui/imports/issue-56125.stderr

@@ -1,17 +1,5 @@
-error[E0433]: failed to resolve: could not find `non_last_segment` in `issue_56125`
- --> $DIR/issue-56125.rs:14:22
- |
-LL | use issue_56125::non_last_segment::non_last_segment::*;
- | ^^^^^^^^^^^^^^^^ could not find `non_last_segment` in `issue_56125`
-
-error[E0432]: unresolved import `issue_56125::last_segment`
- --> $DIR/issue-56125.rs:8:22
- |
-LL | use issue_56125::last_segment::*;
- | ^^^^^^^^^^^^ could not find `last_segment` in `issue_56125`
-
 error[E0432]: unresolved import `empty::issue_56125`
- --> $DIR/issue-56125.rs:21:9
+ --> $DIR/issue-56125.rs:19:9
  |
 LL | use empty::issue_56125; //~ ERROR unresolved import `empty::issue_56125`
  | ^^^^^^^^^^^^^^^^^^ no `issue_56125` in `m3::empty`
@@ -32,36 +20,36 @@ LL | use issue_56125::last_segment::*;
  = help: use `self::issue_56125` to refer to this module unambiguously
 
 error[E0659]: `issue_56125` is ambiguous (name vs any other name during import resolution)
- --> $DIR/issue-56125.rs:14:9
+ --> $DIR/issue-56125.rs:13:9
  |
 LL | use issue_56125::non_last_segment::non_last_segment::*;
  | ^^^^^^^^^^^ ambiguous name
  |
  = note: `issue_56125` could refer to an extern crate passed with `--extern`
  = help: use `::issue_56125` to refer to this extern crate unambiguously
 note: `issue_56125` could also refer to the module imported here
- --> $DIR/issue-56125.rs:14:9
+ --> $DIR/issue-56125.rs:13:9
  |
 LL | use issue_56125::non_last_segment::non_last_segment::*;
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  = help: use `self::issue_56125` to refer to this module unambiguously
 
 error[E0659]: `issue_56125` is ambiguous (name vs any other name during import resolution)
- --> $DIR/issue-56125.rs:22:9
+ --> $DIR/issue-56125.rs:20:9
  |
 LL | use issue_56125::*; //~ ERROR `issue_56125` is ambiguous
  | ^^^^^^^^^^^ ambiguous name
  |
  = note: `issue_56125` could refer to an extern crate passed with `--extern`
  = help: use `::issue_56125` to refer to this extern crate unambiguously
 note: `issue_56125` could also refer to the unresolved item imported here
- --> $DIR/issue-56125.rs:21:9
+ --> $DIR/issue-56125.rs:19:9
  |
 LL | use empty::issue_56125; //~ ERROR unresolved import `empty::issue_56125`
  | ^^^^^^^^^^^^^^^^^^
  = help: use `self::issue_56125` to refer to this unresolved item unambiguously
 
-error: aborting due to 6 previous errors
+error: aborting due to 4 previous errors
 
-Some errors occurred: E0432, E0433, E0659.
+Some errors occurred: E0432, E0659.
 For more information about an error, try `rustc --explain E0432`.