Auto merge of #66592 - estebank:raw-raw-ah-ah-ah, r=cramertj

Rework raw ident suggestions

Use heuristics to determine whethersuggesting raw identifiers is
appropriate.

Account for raw identifiers when printing a path in a `use` suggestion.

Fix #66126.

src/librustc_parse/parser/diagnostics.rs

@@ -225,8 +225,21 @@ impl<'a> Parser<'a> {
  self.token.span,
  &format!("expected identifier, found {}", self.this_token_descr()),
  );
+ let valid_follow = &[
+ TokenKind::Eq,
+ TokenKind::Colon,
+ TokenKind::Comma,
+ TokenKind::Semi,
+ TokenKind::ModSep,
+ TokenKind::OpenDelim(token::DelimToken::Brace),
+ TokenKind::OpenDelim(token::DelimToken::Paren),
+ TokenKind::CloseDelim(token::DelimToken::Brace),
+ TokenKind::CloseDelim(token::DelimToken::Paren),
+ ];
  if let token::Ident(name, false) = self.token.kind {
- if Ident::new(name, self.token.span).is_raw_guess() {
+ if Ident::new(name, self.token.span).is_raw_guess() &&
+ self.look_ahead(1, |t| valid_follow.contains(&t.kind))
+ {
  err.span_suggestion(
  self.token.span,
  "you can escape reserved keywords to use them as identifiers",

src/librustc_resolve/lib.rs

@@ -2894,15 +2894,16 @@ fn names_to_string(names: &[Name]) -> String {
  if i > 0 {
  result.push_str("::");
  }
+ if Ident::with_dummy_span(*name).is_raw_guess() {
+ result.push_str("r#");
+ }
  result.push_str(&name.as_str());
  }
  result
 }
 
 fn path_names_to_string(path: &Path) -> String {
- names_to_string(&path.segments.iter()
- .map(|seg| seg.ident.name)
- .collect::<Vec<_>>())
+ names_to_string(&path.segments.iter().map(|seg| seg.ident.name).collect::<Vec<_>>())
 }
 
 /// A somewhat inefficient routine to obtain the name of a module.

src/test/ui/async-await/no-const-async.stderr

@@ -3,11 +3,6 @@ error: expected identifier, found keyword `async`
  |
 LL | pub const async fn x() {}
  | ^^^^^ expected identifier, found keyword
- |
-help: you can escape reserved keywords to use them as identifiers
- |
-LL | pub const r#async fn x() {}
- | ^^^^^^^
 
 error: expected `:`, found keyword `fn`
  --> $DIR/no-const-async.rs:5:17

src/test/ui/parser/associated-types-project-from-hrtb-explicit.stderr

@@ -3,11 +3,6 @@ error: expected identifier, found keyword `for`
  |
 LL | fn foo2<I>(x: <I as for<'x> Foo<&'x isize>>::A)
  | ^^^ expected identifier, found keyword
- |
-help: you can escape reserved keywords to use them as identifiers
- |
-LL | fn foo2<I>(x: <I as r#for<'x> Foo<&'x isize>>::A)
- | ^^^^^
 
 error: expected one of `::` or `>`, found `Foo`
  --> $DIR/associated-types-project-from-hrtb-explicit.rs:10:29

src/test/ui/parser/mismatched-braces/missing-close-brace-in-struct.stderr

@@ -12,11 +12,6 @@ error: expected identifier, found keyword `trait`
  |
 LL | trait T {
  | ^^^^^ expected identifier, found keyword
- |
-help: you can escape reserved keywords to use them as identifiers
- |
-LL | r#trait T {
- | ^^^^^^^
 
 error: expected `:`, found `T`
  --> $DIR/missing-close-brace-in-struct.rs:4:7

src/test/ui/parser/removed-syntax-field-let.stderr

@@ -3,11 +3,6 @@ error: expected identifier, found keyword `let`
  |
 LL | let foo: (),
  | ^^^ expected identifier, found keyword
- |
-help: you can escape reserved keywords to use them as identifiers
- |
-LL | r#let foo: (),
- | ^^^^^
 
 error: expected `:`, found `foo`
  --> $DIR/removed-syntax-field-let.rs:2:9

src/test/ui/parser/use-as-where-use-ends-with-mod-sep.stderr

@@ -3,11 +3,6 @@ error: expected identifier, found keyword `as`
  |
 LL | use std::any:: as foo;
  | ^^ expected identifier, found keyword
- |
-help: you can escape reserved keywords to use them as identifiers
- |
-LL | use std::any:: r#as foo;
- | ^^^^
 
 error: expected one of `::`, `;`, or `as`, found `foo`
  --> $DIR/use-as-where-use-ends-with-mod-sep.rs:1:19

src/test/ui/suggestions/raw-name-use-suggestion.rs

@@ -0,0 +1,9 @@
+mod foo {
+ pub fn r#let() {}
+ pub fn break() {} //~ ERROR expected identifier, found keyword `break`
+}
+
+fn main() {
+ foo::let(); //~ ERROR expected identifier, found keyword `let`
+ r#break(); //~ ERROR cannot find function `break` in this scope
+}

src/test/ui/suggestions/raw-name-use-suggestion.stderr

@@ -0,0 +1,36 @@
+error: expected identifier, found keyword `break`
+ --> $DIR/raw-name-use-suggestion.rs:3:12
+ |
+LL | pub fn break() {}
+ | ^^^^^ expected identifier, found keyword
+ |
+help: you can escape reserved keywords to use them as identifiers
+ |
+LL | pub fn r#break() {}
+ | ^^^^^^^
+
+error: expected identifier, found keyword `let`
+ --> $DIR/raw-name-use-suggestion.rs:7:10
+ |
+LL | foo::let();
+ | ^^^ expected identifier, found keyword
+ |
+help: you can escape reserved keywords to use them as identifiers
+ |
+LL | foo::r#let();
+ | ^^^^^
+
+error[E0425]: cannot find function `break` in this scope
+ --> $DIR/raw-name-use-suggestion.rs:8:5
+ |
+LL | r#break();
+ | ^^^^^^^ not found in this scope
+ |
+help: possible candidate is found in another module, you can import it into scope
+ |
+LL | use foo::r#break;
+ |
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0425`.

src/test/ui/try-block/try-block-in-edition2015.stderr

@@ -6,11 +6,6 @@ LL | let try_result: Option<_> = try {
 LL |
 LL | let x = 5;
  | ^^^ expected identifier, found keyword
- |
-help: you can escape reserved keywords to use them as identifiers
- |
-LL | r#let x = 5;
- | ^^^^^
 
 error[E0574]: expected struct, variant or union type, found macro `try`
  --> $DIR/try-block-in-edition2015.rs:4:33