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Auto merge of #79364 - nico-abram:unstable-or-pat-suggestion, r=matthewjasper

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Fixes #79357 unstable or-pat suggestions

Fixes #79357
This commit is contained in:
bors 2020-12-02 20:33:55 +00:00
commit f4db9ffb22
2 changed files with 25 additions and 41 deletions
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33
compiler/rustc_parse/src/parser/pat.rs
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@ -18,7 +18,7 @@ pub(super) const PARAM_EXPECTED: Expected = Some("parameter name");
const WHILE_PARSING_OR_MSG: &str = "while parsing this or-pattern starting here";
/// Whether or not an or-pattern should be gated when occurring in the current context.
#[derive(PartialEq)]
#[derive(PartialEq, Clone, Copy)]
pub(super) enum GateOr {
Yes,
No,
@ -94,7 +94,7 @@ impl<'a> Parser<'a> {
) -> PResult<'a, P<Pat>> {
// Parse the first pattern (`p_0`).
let first_pat = self.parse_pat(expected)?;
self.maybe_recover_unexpected_comma(first_pat.span, rc)?;
self.maybe_recover_unexpected_comma(first_pat.span, rc, gate_or)?;
// If the next token is not a `|`,
// this is not an or-pattern and we should exit here.
@ -110,7 +110,7 @@ impl<'a> Parser<'a> {
err.span_label(lo, WHILE_PARSING_OR_MSG);
err
})?;
self.maybe_recover_unexpected_comma(pat.span, rc)?;
self.maybe_recover_unexpected_comma(pat.span, rc, gate_or)?;
pats.push(pat);
}
let or_pattern_span = lo.to(self.prev_token.span);
@ -190,7 +190,12 @@ 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).
fn maybe_recover_unexpected_comma(&mut self, lo: Span, rc: RecoverComma) -> PResult<'a, ()> {
fn maybe_recover_unexpected_comma(
&mut self,
lo: Span,
rc: RecoverComma,
gate_or: GateOr,
) -> PResult<'a, ()> {
if rc == RecoverComma::No || self.token != token::Comma {
return Ok(());
}
@ -209,18 +214,24 @@ impl<'a> Parser<'a> {
let seq_span = lo.to(self.prev_token.span);
let mut err = self.struct_span_err(comma_span, "unexpected `,` in pattern");
if let Ok(seq_snippet) = self.span_to_snippet(seq_span) {
const MSG: &str = "try adding parentheses to match on a tuple...";
let or_suggestion =
gate_or == GateOr::No || !self.sess.gated_spans.is_ungated(sym::or_patterns);
err.span_suggestion(
seq_span,
"try adding parentheses to match on a tuple...",
if or_suggestion { MSG } else { MSG.trim_end_matches('.') },
format!("({})", seq_snippet),
Applicability::MachineApplicable,
)
.span_suggestion(
seq_span,
"...or a vertical bar to match on multiple alternatives",
seq_snippet.replace(",", " |"),
Applicability::MachineApplicable,
);
if or_suggestion {
err.span_suggestion(
seq_span,
"...or a vertical bar to match on multiple alternatives",
seq_snippet.replace(",", " |"),
Applicability::MachineApplicable,
);
}
}
Err(err)
}