From 62867b499291a69f5df16a60228c6bcedc5e4225 Mon Sep 17 00:00:00 2001
From: Knium_ <hi.im.knium@gmail.com>
Date: Wed, 30 Jan 2019 13:50:44 +0900
Subject: [PATCH] Suggest to add each of `|` and `()` when unexpected `,` is
 found in pattern

---
 src/libsyntax/parse/parser.rs                 |  7 ++-
 ...92-tuple-destructure-missing-parens.stderr | 60 +++++++++++++++++--
 2 files changed, 60 insertions(+), 7 deletions(-)

diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs
index 65572102c5981..514b2952c5036 100644
--- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -4381,9 +4381,14 @@ impl<'a> Parser<'a> {
             if let Ok(seq_snippet) = self.sess.source_map().span_to_snippet(seq_span) {
                 err.span_suggestion(
                     seq_span,
-                    "try adding parentheses",
+                    "try adding parentheses to match on a tuple..",
                     format!("({})", seq_snippet),
                     Applicability::MachineApplicable
+                ).span_suggestion(
+                    seq_span,
+                    "..or a vertical bar to match on multiple alternatives",
+                    format!("{}", seq_snippet.replace(",", " |")),
+                    Applicability::MachineApplicable
                 );
             }
             return Err(err);
diff --git a/src/test/ui/did_you_mean/issue-48492-tuple-destructure-missing-parens.stderr b/src/test/ui/did_you_mean/issue-48492-tuple-destructure-missing-parens.stderr
index 9df881e8e26d9..8099c3c0584fc 100644
--- a/src/test/ui/did_you_mean/issue-48492-tuple-destructure-missing-parens.stderr
+++ b/src/test/ui/did_you_mean/issue-48492-tuple-destructure-missing-parens.stderr
@@ -2,37 +2,85 @@ error: unexpected `,` in pattern
   --> $DIR/issue-48492-tuple-destructure-missing-parens.rs:38:17
    |
 LL |     while let b1, b2, b3 = reading_frame.next().expect("there should be a start codon") {
-   |               --^------- help: try adding parentheses: `(b1, b2, b3)`
+   |                 ^
+help: try adding parentheses to match on a tuple..
+   |
+LL |     while let (b1, b2, b3) = reading_frame.next().expect("there should be a start codon") {
+   |               ^^^^^^^^^^^^
+help: ..or a vertical bar to match on multiple alternatives
+   |
+LL |     while let b1 | b2 | b3 = reading_frame.next().expect("there should be a start codon") {
+   |               ^^^^^^^^^^^^
 
 error: unexpected `,` in pattern
   --> $DIR/issue-48492-tuple-destructure-missing-parens.rs:49:14
    |
 LL |     if let b1, b2, b3 = reading_frame.next().unwrap() {
-   |            --^------- help: try adding parentheses: `(b1, b2, b3)`
+   |              ^
+help: try adding parentheses to match on a tuple..
+   |
+LL |     if let (b1, b2, b3) = reading_frame.next().unwrap() {
+   |            ^^^^^^^^^^^^
+help: ..or a vertical bar to match on multiple alternatives
+   |
+LL |     if let b1 | b2 | b3 = reading_frame.next().unwrap() {
+   |            ^^^^^^^^^^^^
 
 error: unexpected `,` in pattern
   --> $DIR/issue-48492-tuple-destructure-missing-parens.rs:59:28
    |
 LL |         Nucleotide::Adenine, Nucleotide::Cytosine, _ => true
-   |         -------------------^------------------------ help: try adding parentheses: `(Nucleotide::Adenine, Nucleotide::Cytosine, _)`
+   |                            ^
+help: try adding parentheses to match on a tuple..
+   |
+LL |         (Nucleotide::Adenine, Nucleotide::Cytosine, _) => true
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+help: ..or a vertical bar to match on multiple alternatives
+   |
+LL |         Nucleotide::Adenine | Nucleotide::Cytosine | _ => true
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 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: `(x, _barr_body)`
+   |          ^
+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()) {
+   |         ^^^^^^^^^^^^^^
 
 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: `(x, y @ Allosome::Y(_))`
+   |          ^
+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()) {
+   |         ^^^^^^^^^^^^^^^^^^^^^^
 
 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: `(women, men)`
+   |              ^
+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()
+   |         ^^^^^^^^^^^
 
 error: aborting due to 6 previous errors