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

Fixes rust-lang#79357 unstable or-pat suggestions

Fixes rust-lang#79357

Author: bors

compiler/rustc_parse/src/parser/pat.rs

@@ -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)
     }

src/test/ui/did_you_mean/issue-48492-tuple-destructure-missing-parens.stderr

@@ -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