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Fixes #79357 unstable or-pat suggestions #79364

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Merged
merged 1 commit into from
Dec 2, 2020
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Fixes #79357 unstable or-pat suggestions #79364

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33 changes: 22 additions & 11 deletions compiler/rustc_parse/src/parser/pat.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -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,
Expand Down Expand Up @@ -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.
Expand All @@ -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);
Expand Down Expand Up @@ -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(());
}
Expand All @@ -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)
}
Expand Down
33 changes: 3 additions & 30 deletions src/test/ui/did_you_mean/issue-48492-tuple-destructure-missing-parens.stderr
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Original file line number Diff line number Diff line change
Expand Up @@ -47,46 +47,19 @@ error: unexpected `,` in pattern
--> $DIR/issue-48492-tuple-destructure-missing-parens.rs:67:10
|
LL | for x, _barr_body in women.iter().map(|woman| woman.allosomes.clone()) {
| ^
|
help: try adding parentheses to match on a tuple...
|
LL | for (x, _barr_body) in women.iter().map(|woman| woman.allosomes.clone()) {
| ^^^^^^^^^^^^^^^
help: ...or a vertical bar to match on multiple alternatives
|
LL | for x | _barr_body in women.iter().map(|woman| woman.allosomes.clone()) {
| ^^^^^^^^^^^^^^
| -^----------- help: try adding parentheses to match on a tuple: `(x, _barr_body)`

error: unexpected `,` in pattern
--> $DIR/issue-48492-tuple-destructure-missing-parens.rs:75:10
|
LL | for x, y @ Allosome::Y(_) in men.iter().map(|man| man.allosomes.clone()) {
| ^
|
help: try adding parentheses to match on a tuple...
|
LL | for (x, y @ Allosome::Y(_)) in men.iter().map(|man| man.allosomes.clone()) {
| ^^^^^^^^^^^^^^^^^^^^^^^
help: ...or a vertical bar to match on multiple alternatives
|
LL | for x | y @ Allosome::Y(_) in men.iter().map(|man| man.allosomes.clone()) {
| ^^^^^^^^^^^^^^^^^^^^^^
| -^------------------- help: try adding parentheses to match on a tuple: `(x, y @ Allosome::Y(_))`

error: unexpected `,` in pattern
--> $DIR/issue-48492-tuple-destructure-missing-parens.rs:84:14
|
LL | let women, men: (Vec<Genome>, Vec<Genome>) = genomes.iter().cloned()
| ^
|
help: try adding parentheses to match on a tuple...
|
LL | let (women, men): (Vec<Genome>, Vec<Genome>) = genomes.iter().cloned()
| ^^^^^^^^^^^^
help: ...or a vertical bar to match on multiple alternatives
|
LL | let women | men: (Vec<Genome>, Vec<Genome>) = genomes.iter().cloned()
| ^^^^^^^^^^^
| -----^---- help: try adding parentheses to match on a tuple: `(women, men)`

error: aborting due to 6 previous errors