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Explain why Self is invalid in generic parameters

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Hirochika Matsumoto 2021-10-19 01:31:23 +09:00
parent d45ed7502a
commit a72dd4a5b9
3 changed files with 35 additions and 13 deletions
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13
compiler/rustc_parse/src/parser/generics.rs
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@ -89,6 +89,19 @@ impl<'a> Parser<'a> {
let attrs = self.parse_outer_attributes()?;
let param =
self.collect_tokens_trailing_token(attrs, ForceCollect::No, |this, attrs| {
if this.eat_keyword_noexpect(kw::SelfUpper) {
// `Self` as a generic param is invalid. Here we emit the diagnostic and continue parsing
// as if `Self` never existed.
this.struct_span_err(
this.prev_token.span,
"unexpected keyword `Self` in generic parameters",
)
.note("you cannot use `Self` as a generic parameter because it is reserved for associated items")
.emit();
this.eat(&token::Comma);
}
let param = if this.check_lifetime() {
let lifetime = this.expect_lifetime();
// Parse lifetime parameter.