Add help in case ref and mut are switched #43451
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r? @pnkfelix (rust_highfive has picked a reviewer for you, use r? to override) |
carols10cents
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src/libsyntax/parse/parser.rs
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| self.span_err(self.span, &format!("expected identifier, found {}", | ||
| self.this_token_descr())); | ||
| let desc = self.this_token_descr(); | ||
| if desc == "keyword `ref`" { |
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I think the correct way of doing this is self.token.is_keyword(keyword::Ref)
src/libsyntax/parse/parser.rs
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| self.this_token_descr())); | ||
| let desc = self.this_token_descr(); | ||
| if desc == "keyword `ref`" { | ||
| self.span_err_help(self.span, |
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I think this is a prime candidate for span_suggestion
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I wondered for a while between the both of them. But if you prefer suggestion, I'll totally update to it.
GuillaumeGomez
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Updated. |
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I believe the correct fix should look like this: --- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -3523,8 +3523,18 @@ impl<'a> Parser<'a> {
}
// At this point, token != _, &, &&, (, [
_ => if self.eat_keyword(keywords::Mut) {
- // Parse mut ident @ pat
- pat = self.parse_pat_ident(BindingMode::ByValue(Mutability::Mutable))?;
+ // Parse mut ident @ pat / mut ref ident @ pat
+ let mutref_span = self.prev_span.to(self.span);
+ let binding_mode = if self.eat_keyword(keywords::Ref) {
+ self.diagnostic()
+ .struct_span_err(mutref_span, "the order of `mut` and `ref` is incorrect")
+ .span_suggestion(mutref_span, "try switching the order", "ref mut".into())
+ .emit();
+ BindingMode::ByRef(Mutability::Mutable)
+ } else {
+ BindingMode::ByValue(Mutability::Mutable)
+ };
+ pat = self.parse_pat_ident(binding_mode)?;
} else if self.eat_keyword(keywords::Ref) {
// Parse ref ident @ pat / ref mut ident @ pat
let mutbl = self.parse_mutability(); |
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@petrochenkov: Well, you did it. I can take your patch and apply but you sure you don't want to open a PR yourself? I'd feel bad to take it from you. :-/ |
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@GuillaumeGomez |
Better diagnostics and recovery for `mut ref` in patterns Fixes #43286 Supersedes #43451 r? @GuillaumeGomez
Fixes #43286.