From f10da9f50ac7d083b2f5b2bc8b84c777ed411973 Mon Sep 17 00:00:00 2001
From: Chayim Refael Friedman <chayimfr@gmail.com>
Date: Fri, 14 May 2021 00:44:58 +0300
Subject: [PATCH] Allow leading pipe in `matches!()` patterns.

This is allowed in `match` statement, and stated in https://internals.rust-lang.org/t/leading-pipe-in-core-matches/14699/2 that it should be allowed in these macros too.
---
 library/core/src/macros/mod.rs | 6 +++---
 library/core/tests/macros.rs   | 6 ++++++
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/library/core/src/macros/mod.rs b/library/core/src/macros/mod.rs
index 8ce441e80bfb7..d26699e26e35a 100644
--- a/library/core/src/macros/mod.rs
+++ b/library/core/src/macros/mod.rs
@@ -141,7 +141,7 @@ macro_rules! assert_ne {
 #[allow_internal_unstable(core_panic)]
 #[rustc_macro_transparency = "semitransparent"]
 pub macro assert_matches {
-    ($left:expr, $( $pattern:pat_param )|+ $( if $guard: expr )? $(,)?) => ({
+    ($left:expr, $(|)? $( $pattern:pat_param )|+ $( if $guard: expr )? $(,)?) => ({
         match $left {
             $( $pattern )|+ $( if $guard )? => {}
             ref left_val => {
@@ -153,7 +153,7 @@ pub macro assert_matches {
             }
         }
     }),
-    ($left:expr, $( $pattern:pat_param )|+ $( if $guard: expr )?, $($arg:tt)+) => ({
+    ($left:expr, $(|)? $( $pattern:pat_param )|+ $( if $guard: expr )?, $($arg:tt)+) => ({
         match $left {
             $( $pattern )|+ $( if $guard )? => {}
             ref left_val => {
@@ -321,7 +321,7 @@ pub macro debug_assert_matches($($arg:tt)*) {
 #[macro_export]
 #[stable(feature = "matches_macro", since = "1.42.0")]
 macro_rules! matches {
-    ($expression:expr, $( $pattern:pat_param )|+ $( if $guard: expr )? $(,)?) => {
+    ($expression:expr, $(|)? $( $pattern:pat_param )|+ $( if $guard: expr )? $(,)?) => {
         match $expression {
             $( $pattern )|+ $( if $guard )? => true,
             _ => false
diff --git a/library/core/tests/macros.rs b/library/core/tests/macros.rs
index 482f3c1c99840..ff3632e3550c2 100644
--- a/library/core/tests/macros.rs
+++ b/library/core/tests/macros.rs
@@ -12,3 +12,9 @@ fn assert_escape() {
 fn assert_ne_trailing_comma() {
     assert_ne!(1, 2,);
 }
+
+#[rustfmt::skip]
+#[test]
+fn matches_leading_pipe() {
+    matches!(1, | 1 | 2 | 3);
+}