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Emit more pretty diagnostics for qualified paths

This commit is contained in:
Yuki Okushi 2021-03-17 09:49:46 +09:00
parent 8240f1a3d3
commit 2d99e68940
2 changed files with 29 additions and 14 deletions
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35
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 {
@ -1618,6 +1618,8 @@ impl<'a> Parser<'a> {
|| 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,
@ -1626,7 +1628,9 @@ impl<'a> Parser<'a> {
format!("_: {}", ident),
),
// Also catches `fn foo(&a)`.
PatKind::Ref(ref pat, mutab) => {
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();
@ -1637,20 +1641,23 @@ impl<'a> Parser<'a> {
format!("_: &{}{}", mutab, ident),
)
}
PatKind::Path(..) => {
err.note("anonymous parameters are removed in the 2018 edition (see RFC 1685)");
return None;
}
_ => return None,
_ => unreachable!(),
}
}
// Also catches `fn foo(<Bar as T>::Baz)`
PatKind::Path(..) => {
err.note("anonymous parameters are removed in the 2018 edition (see RFC 1685)");
_ => {
// 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;
}
// Ignore other `PatKind`.
_ => return None,
};
// `fn foo(a, b) {}`, `fn foo(a<x>, b<y>) {}` or `fn foo(usize, usize) {}`
@ -1678,7 +1685,7 @@ impl<'a> Parser<'a> {
type_sugg,
Applicability::MachineApplicable,
);
err.note("anonymous parameters are removed in the 2018 edition (see RFC 1685)");
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) };

8
src/test/ui/anon-params/anon-params-denied-2018.stderr
View File

@ -45,6 +45,10 @@ LL | fn foo_with_qualified_path(<Bar as T>::Baz);
| ^ expected one of 8 possible tokens
|
= note: anonymous parameters are removed in the 2018 edition (see RFC 1685)
help: explicitly ignore the parameter name
|
LL | fn foo_with_qualified_path(_: <Bar as T>::Baz);
| ^^^^^^^^^^^^^^^^^^
error: expected one of `(`, `...`, `..=`, `..`, `::`, `:`, `{`, or `|`, found `)`
--> $DIR/anon-params-denied-2018.rs:15:56
@ -53,6 +57,10 @@ LL | fn foo_with_qualified_path_and_ref(&<Bar as T>::Baz);
| ^ expected one of 8 possible tokens
|
= note: anonymous parameters are removed in the 2018 edition (see RFC 1685)
help: explicitly ignore the parameter name
|
LL | fn foo_with_qualified_path_and_ref(_: &<Bar as T>::Baz);
| ^^^^^^^^^^^^^^^^^^^
error: expected one of `:`, `@`, or `|`, found `,`
--> $DIR/anon-params-denied-2018.rs:18:36