Suggest fixes and add error recovery for use foo::self

src/librustc_resolve/build_reduced_graph.rs

@@ -426,7 +426,7 @@ impl<'a, 'b> BuildReducedGraphVisitor<'a, 'b> {
  return;
  }
 
- // Replace `use foo::self;` with `use foo;`
+ // Replace `use foo::{ self };` with `use foo;`
  source = module_path.pop().unwrap();
  if rename.is_none() {
  ident = source.ident;
@@ -435,10 +435,33 @@ impl<'a, 'b> BuildReducedGraphVisitor<'a, 'b> {
  } else {
  // Disallow `self`
  if source.ident.name == kw::SelfLower {
+ let parent = module_path.last();
+
+ let span = match parent {
+ // only `::self` from `use foo::self as bar`
+ Some(seg) => seg.ident.span.shrink_to_hi().to(source.ident.span),
+ None => source.ident.span,
+ };
+ let span_with_rename = match rename {
+ // only `self as bar` from `use foo::self as bar`
+ Some(rename) => source.ident.span.to(rename.span),
+ None => source.ident.span,
+ };
  self.r.report_error(
- use_tree.span,
- ResolutionError::SelfImportsOnlyAllowedWithin,
+ span,
+ ResolutionError::SelfImportsOnlyAllowedWithin {
+ root: parent.is_none(),
+ span_with_rename,
+ },
  );
+
+ // Error recovery: replace `use foo::self;` with `use foo;`
+ if let Some(parent) = module_path.pop() {
+ source = parent;
+ if rename.is_none() {
+ ident = source.ident;
+ }
+ }
  }
 
  // Disallow `use $crate;`

src/librustc_resolve/diagnostics.rs

@@ -301,13 +301,40 @@ impl<'a> Resolver<'a> {
  }
  err
  }
- ResolutionError::SelfImportsOnlyAllowedWithin => struct_span_err!(
- self.session,
- span,
- E0429,
- "{}",
- "`self` imports are only allowed within a { } list"
- ),
+ ResolutionError::SelfImportsOnlyAllowedWithin { root, span_with_rename } => {
+ let mut err = struct_span_err!(
+ self.session,
+ span,
+ E0429,
+ "{}",
+ "`self` imports are only allowed within a { } list"
+ );
+
+ // None of the suggestions below would help with a case like `use self`.
+ if !root {
+ // use foo::bar::self -> foo::bar
+ // use foo::bar::self as abc -> foo::bar as abc
+ err.span_suggestion(
+ span,
+ "consider importing the module directly",
+ "".to_string(),
+ Applicability::MachineApplicable,
+ );
+
+ // use foo::bar::self -> foo::bar::{self}
+ // use foo::bar::self as abc -> foo::bar::{self as abc}
+ let braces = vec![
+ (span_with_rename.shrink_to_lo(), "{".to_string()),
+ (span_with_rename.shrink_to_hi(), "}".to_string()),
+ ];
+ err.multipart_suggestion(
+ "alternatively, use the multi-path `use` syntax to import `self`",
+ braces,
+ Applicability::MachineApplicable,
+ );
+ }
+ err
+ }
  ResolutionError::SelfImportCanOnlyAppearOnceInTheList => {
  let mut err = struct_span_err!(
  self.session,

src/librustc_resolve/lib.rs

@@ -194,7 +194,7 @@ enum ResolutionError<'a> {
  /// Error E0426: use of undeclared label.
  UndeclaredLabel(&'a str, Option<Symbol>),
  /// Error E0429: `self` imports are only allowed within a `{ }` list.
- SelfImportsOnlyAllowedWithin,
+ SelfImportsOnlyAllowedWithin { root: bool, span_with_rename: Span },
  /// Error E0430: `self` import can only appear once in the list.
  SelfImportCanOnlyAppearOnceInTheList,
  /// Error E0431: `self` import can only appear in an import list with a non-empty prefix.

src/test/ui/error-codes/E0429.stderr

@@ -1,8 +1,17 @@
 error[E0429]: `self` imports are only allowed within a { } list
- --> $DIR/E0429.rs:1:5
+ --> $DIR/E0429.rs:1:13
  |
 LL | use std::fmt::self;
- | ^^^^^^^^^^^^^^
+ | ^^^^^^
+ |
+help: consider importing the module directly
+ |
+LL | use std::fmt;
+ | --
+help: alternatively, use the multi-path `use` syntax to import `self`
+ |
+LL | use std::fmt::{self};
+ | ^ ^
 
 error: aborting due to previous error
 

src/test/ui/issues/issue-45829/import-self.rs

@@ -9,7 +9,7 @@ use foo::{self};
 use foo as self;
 //~^ ERROR expected identifier
 
-use foo::self;
+use foo::self; //~ ERROR is defined multiple times
 //~^ ERROR `self` imports are only allowed within a { } list
 
 use foo::A;

src/test/ui/issues/issue-45829/import-self.stderr

@@ -5,10 +5,19 @@ LL | use foo as self;
  | ^^^^ expected identifier, found keyword
 
 error[E0429]: `self` imports are only allowed within a { } list
- --> $DIR/import-self.rs:12:5
+ --> $DIR/import-self.rs:12:8
  |
 LL | use foo::self;
- | ^^^^^^^^^
+ | ^^^^^^
+ |
+help: consider importing the module directly
+ |
+LL | use foo;
+ | --
+help: alternatively, use the multi-path `use` syntax to import `self`
+ |
+LL | use foo::{self};
+ | ^ ^
 
 error[E0255]: the name `foo` is defined multiple times
  --> $DIR/import-self.rs:6:11
@@ -25,6 +34,21 @@ help: you can use `as` to change the binding name of the import
 LL | use foo::{self as other_foo};
  | ^^^^^^^^^^^^^^^^^
 
+error[E0255]: the name `foo` is defined multiple times
+ --> $DIR/import-self.rs:12:5
+ |
+LL | mod foo {
+ | ------- previous definition of the module `foo` here
+...
+LL | use foo::self;
+ | ^^^^^^^^^ `foo` reimported here
+ |
+ = note: `foo` must be defined only once in the type namespace of this module
+help: you can use `as` to change the binding name of the import
+ |
+LL | use foo as other_foo;
+ | ^^^^^^^^^^^^^^^^
+
 error[E0252]: the name `A` is defined multiple times
  --> $DIR/import-self.rs:16:11
  |
@@ -39,7 +63,7 @@ help: you can use `as` to change the binding name of the import
 LL | use foo::{self as OtherA};
  | ^^^^^^^^^^^^^^
 
-error: aborting due to 4 previous errors
+error: aborting due to 5 previous errors
 
 Some errors have detailed explanations: E0252, E0255, E0429.
 For more information about an error, try `rustc --explain E0252`.

src/test/ui/use/use-keyword.stderr

@@ -2,7 +2,7 @@ error[E0429]: `self` imports are only allowed within a { } list
  --> $DIR/use-keyword.rs:6:13
  |
 LL | use self as A;
- | ^^^^^^^^^
+ | ^^^^
 
 error[E0432]: unresolved import `super`
  --> $DIR/use-keyword.rs:8:13

src/test/ui/use/use-mod/use-mod-4.stderr

@@ -1,20 +1,38 @@
 error[E0429]: `self` imports are only allowed within a { } list
- --> $DIR/use-mod-4.rs:1:5
+ --> $DIR/use-mod-4.rs:1:8
  |
 LL | use foo::self;
- | ^^^^^^^^^
+ | ^^^^^^
+ |
+help: consider importing the module directly
+ |
+LL | use foo;
+ | --
+help: alternatively, use the multi-path `use` syntax to import `self`
+ |
+LL | use foo::{self};
+ | ^ ^
 
 error[E0429]: `self` imports are only allowed within a { } list
- --> $DIR/use-mod-4.rs:4:5
+ --> $DIR/use-mod-4.rs:4:13
  |
 LL | use std::mem::self;
- | ^^^^^^^^^^^^^^
+ | ^^^^^^
+ |
+help: consider importing the module directly
+ |
+LL | use std::mem;
+ | --
+help: alternatively, use the multi-path `use` syntax to import `self`
+ |
+LL | use std::mem::{self};
+ | ^ ^
 
 error[E0432]: unresolved import `foo`
  --> $DIR/use-mod-4.rs:1:5
  |
 LL | use foo::self;
- | ^^^ maybe a missing crate `foo`?
+ | ^^^^^^^^^ no `foo` in the root
 
 error: aborting due to 3 previous errors
 

src/test/ui/use/use-mod/use-mod-5.rs

@@ -0,0 +1,13 @@
+mod foo {
+ pub mod bar {
+ pub fn drop() {}
+ }
+}
+
+use foo::bar::self;
+//~^ ERROR `self` imports are only allowed within a { } list
+
+fn main() {
+ // Because of error recovery this shouldn't error
+ bar::drop();
+}

src/test/ui/use/use-mod/use-mod-5.stderr

@@ -0,0 +1,18 @@
+error[E0429]: `self` imports are only allowed within a { } list
+ --> $DIR/use-mod-5.rs:7:13
+ |
+LL | use foo::bar::self;
+ | ^^^^^^
+ |
+help: consider importing the module directly
+ |
+LL | use foo::bar;
+ | --
+help: alternatively, use the multi-path `use` syntax to import `self`
+ |
+LL | use foo::bar::{self};
+ | ^ ^
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0429`.

src/test/ui/use/use-mod/use-mod-6.rs

@@ -0,0 +1,13 @@
+mod foo {
+ pub mod bar {
+ pub fn drop() {}
+ }
+}
+
+use foo::bar::self as abc;
+//~^ ERROR `self` imports are only allowed within a { } list
+
+fn main() {
+ // Because of error recovery this shouldn't error
+ abc::drop();
+}

src/test/ui/use/use-mod/use-mod-6.stderr

@@ -0,0 +1,18 @@
+error[E0429]: `self` imports are only allowed within a { } list
+ --> $DIR/use-mod-6.rs:7:13
+ |
+LL | use foo::bar::self as abc;
+ | ^^^^^^
+ |
+help: consider importing the module directly
+ |
+LL | use foo::bar as abc;
+ | --
+help: alternatively, use the multi-path `use` syntax to import `self`
+ |
+LL | use foo::bar::{self as abc};
+ | ^ ^
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0429`.