bjoernager/rust
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Teach parser to understand fake anonymous enum syntax

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Parse `-> Ty | OtherTy`.
Parse type ascription in top level patterns.
This commit is contained in:
Esteban Küber 2023-01-15 22:36:46 +00:00
parent ae4d89dfb5
commit 2d82420665
13 changed files with 270 additions and 40 deletions
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50
compiler/rustc_parse/src/parser/diagnostics.rs
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@ -2372,7 +2372,7 @@ impl<'a> Parser<'a> {
/// Some special error handling for the "top-level" patterns in a match arm,
/// `for` loop, `let`, &c. (in contrast to subpatterns within such).
pub(crate) fn maybe_recover_colon_colon_in_pat_typo(
pub(crate) fn maybe_recover_colon_colon_in_pat_typo_or_anon_enum(
&mut self,
mut first_pat: P<Pat>,
expected: Expected,
@ -2383,26 +2383,41 @@ impl<'a> Parser<'a> {
if !matches!(first_pat.kind, PatKind::Ident(_, _, None) | PatKind::Path(..))
|| !self.look_ahead(1, |token| token.is_ident() && !token.is_reserved_ident())
{
let mut snapshot_type = self.create_snapshot_for_diagnostic();
snapshot_type.bump(); // `:`
match snapshot_type.parse_ty() {
Err(inner_err) => {
inner_err.cancel();
}
Ok(ty) => {
let Err(mut err) = self.expected_one_of_not_found(&[], &[]) else {
return first_pat;
};
err.span_label(ty.span, "specifying the type of a pattern isn't supported");
self.restore_snapshot(snapshot_type);
let span = first_pat.span.to(ty.span);
first_pat = self.mk_pat(span, PatKind::Wild);
err.emit();
}
}
return first_pat;
}
// The pattern looks like it might be a path with a `::` -> `:` typo:
// `match foo { bar:baz => {} }`
let span = self.token.span;
let colon_span = self.token.span;
// We only emit "unexpected `:`" error here if we can successfully parse the
// whole pattern correctly in that case.
let snapshot = self.create_snapshot_for_diagnostic();
let mut snapshot_pat = self.create_snapshot_for_diagnostic();
let mut snapshot_type = self.create_snapshot_for_diagnostic();
// Create error for "unexpected `:`".
match self.expected_one_of_not_found(&[], &[]) {
Err(mut err) => {
self.bump(); // Skip the `:`.
match self.parse_pat_no_top_alt(expected) {
snapshot_pat.bump(); // Skip the `:`.
snapshot_type.bump(); // Skip the `:`.
match snapshot_pat.parse_pat_no_top_alt(expected) {
Err(inner_err) => {
// Carry on as if we had not done anything, callers will emit a
// reasonable error.
inner_err.cancel();
err.cancel();
self.restore_snapshot(snapshot);
}
Ok(mut pat) => {
// We've parsed the rest of the pattern.
@ -2466,8 +2481,8 @@ impl<'a> Parser<'a> {
_ => {}
}
if show_sugg {
err.span_suggestion(
span,
err.span_suggestion_verbose(
colon_span.until(self.look_ahead(1, |t| t.span)),
"maybe write a path separator here",
"::",
Applicability::MaybeIncorrect,
@ -2475,13 +2490,22 @@ impl<'a> Parser<'a> {
} else {
first_pat = self.mk_pat(new_span, PatKind::Wild);
}
err.emit();
self.restore_snapshot(snapshot_pat);
}
}
match snapshot_type.parse_ty() {
Err(inner_err) => {
inner_err.cancel();
}
Ok(ty) => {
err.span_label(ty.span, "specifying the type of a pattern isn't supported");
self.restore_snapshot(snapshot_type);
}
}
err.emit();
}
_ => {
// Carry on as if we had not done anything. This should be unreachable.
self.restore_snapshot(snapshot);
}
};
first_pat