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Rollup merge of #82774 - JohnTitor:bad-diag-for-anon-params-with-ref, r=estebank

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Fix bad diagnostics for anon params with ref and/or qualified paths

Fixes #82729
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This commit is contained in:
Yuki Okushi 2021-03-17 15:20:48 +09:00 • committed by GitHub
commit a16db3dcda
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4 changed files with 172 additions and 36 deletions
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104
compiler/rustc_parse/src/parser/diagnostics.rs
View file

@ -640,7 +640,7 @@ impl<'a> Parser<'a> {
}
}
Err(mut err) => {
// We could't parse generic parameters, unlikely to be a turbofish. Rely on
// We couldn't parse generic parameters, unlikely to be a turbofish. Rely on
// generic parse error instead.
err.cancel();
*self = snapshot;
@ -1242,7 +1242,7 @@ impl<'a> Parser<'a> {
let is_question = self.eat(&token::Question); // Handle `await? <expr>`.
let expr = if self.token == token::OpenDelim(token::Brace) {
// Handle `await { <expr> }`.
// This needs to be handled separatedly from the next arm to avoid
// This needs to be handled separately from the next arm to avoid
// interpreting `await { <expr> }?` as `<expr>?.await`.
self.parse_block_expr(None, self.token.span, BlockCheckMode::Default, AttrVec::new())
} else {
@ -1613,42 +1613,82 @@ impl<'a> Parser<'a> {
Applicability::HasPlaceholders,
);
return Some(ident);
} else if let PatKind::Ident(_, ident, _) = pat.kind {
if require_name
&& (self.token == token::Comma
|| self.token == token::Lt
|| self.token == token::CloseDelim(token::Paren))
{
// `fn foo(a, b) {}`, `fn foo(a<x>, b<y>) {}` or `fn foo(usize, usize) {}`
if first_param {
err.span_suggestion(
pat.span,
"if this is a `self` type, give it a parameter name",
format!("self: {}", ident),
Applicability::MaybeIncorrect,
);
} else if require_name
&& (self.token == token::Comma
|| self.token == token::Lt
|| self.token == token::CloseDelim(token::Paren))
{
let rfc_note = "anonymous parameters are removed in the 2018 edition (see RFC 1685)";
let (ident, self_sugg, param_sugg, type_sugg) = match pat.kind {
PatKind::Ident(_, ident, _) => (
ident,
format!("self: {}", ident),
format!("{}: TypeName", ident),
format!("_: {}", ident),
),
// Also catches `fn foo(&a)`.
PatKind::Ref(ref pat, mutab)
if matches!(pat.clone().into_inner().kind, PatKind::Ident(..)) =>
{
match pat.clone().into_inner().kind {
PatKind::Ident(_, ident, _) => {
let mutab = mutab.prefix_str();
(
ident,
format!("self: &{}{}", mutab, ident),
format!("{}: &{}TypeName", ident, mutab),
format!("_: &{}{}", mutab, ident),
)
}
_ => unreachable!(),
}
}
// Avoid suggesting that `fn foo(HashMap<u32>)` is fixed with a change to
// `fn foo(HashMap: TypeName<u32>)`.
if self.token != token::Lt {
err.span_suggestion(
pat.span,
"if this is a parameter name, give it a type",
format!("{}: TypeName", ident),
Applicability::HasPlaceholders,
);
_ => {
// Otherwise, try to get a type and emit a suggestion.
if let Some(ty) = pat.to_ty() {
err.span_suggestion_verbose(
pat.span,
"explicitly ignore the parameter name",
format!("_: {}", pprust::ty_to_string(&ty)),
Applicability::MachineApplicable,
);
err.note(rfc_note);
}
return None;
}
};
// `fn foo(a, b) {}`, `fn foo(a<x>, b<y>) {}` or `fn foo(usize, usize) {}`
if first_param {
err.span_suggestion(
pat.span,
"if this is a type, explicitly ignore the parameter name",
format!("_: {}", ident),
Applicability::MachineApplicable,
"if this is a `self` type, give it a parameter name",
self_sugg,
Applicability::MaybeIncorrect,
);
err.note("anonymous parameters are removed in the 2018 edition (see RFC 1685)");
// Don't attempt to recover by using the `X` in `X<Y>` as the parameter name.
return if self.token == token::Lt { None } else { Some(ident) };
}
// Avoid suggesting that `fn foo(HashMap<u32>)` is fixed with a change to
// `fn foo(HashMap: TypeName<u32>)`.
if self.token != token::Lt {
err.span_suggestion(
pat.span,
"if this is a parameter name, give it a type",
param_sugg,
Applicability::HasPlaceholders,
);
}
err.span_suggestion(
pat.span,
"if this is a type, explicitly ignore the parameter name",
type_sugg,
Applicability::MachineApplicable,
);
err.note(rfc_note);
// Don't attempt to recover by using the `X` in `X<Y>` as the parameter name.
return if self.token == token::Lt { None } else { Some(ident) };
}
None
}