From 083963e58c752f1a51b67d65dc6a207bf69f1d64 Mon Sep 17 00:00:00 2001
From: Mazdak Farrokhzad <twingoow@gmail.com>
Date: Sun, 25 Aug 2019 01:50:21 +0200
Subject: [PATCH] parser: 'while parsing this or-pattern...'

---
 src/libsyntax/parse/parser/pat.rs                      |  5 ++++-
 .../ui/or-patterns/while-parsing-this-or-pattern.rs    |  9 +++++++++
 .../or-patterns/while-parsing-this-or-pattern.stderr   | 10 ++++++++++
 3 files changed, 23 insertions(+), 1 deletion(-)
 create mode 100644 src/test/ui/or-patterns/while-parsing-this-or-pattern.rs
 create mode 100644 src/test/ui/or-patterns/while-parsing-this-or-pattern.stderr

diff --git a/src/libsyntax/parse/parser/pat.rs b/src/libsyntax/parse/parser/pat.rs
index 7c09dc4e566..a0278fa4077 100644
--- a/src/libsyntax/parse/parser/pat.rs
+++ b/src/libsyntax/parse/parser/pat.rs
@@ -81,7 +81,10 @@ fn parse_pat_with_or(&mut self, gate_or: GateOr, top_level: TopLevel) -> PResult
         let lo = first_pat.span;
         let mut pats = vec![first_pat];
         while self.eat_or_separator() {
-            let pat = self.parse_pat(None)?;
+            let pat = self.parse_pat(None).map_err(|mut err| {
+                err.span_label(lo, "while parsing this or-pattern staring here");
+                err
+            })?;
             self.maybe_recover_unexpected_comma(pat.span, top_level)?;
             pats.push(pat);
         }
diff --git a/src/test/ui/or-patterns/while-parsing-this-or-pattern.rs b/src/test/ui/or-patterns/while-parsing-this-or-pattern.rs
new file mode 100644
index 00000000000..4a9fae1406a
--- /dev/null
+++ b/src/test/ui/or-patterns/while-parsing-this-or-pattern.rs
@@ -0,0 +1,9 @@
+// Test the parser for the "while parsing this or-pattern..." label here.
+
+fn main() {
+    match Some(42) {
+        Some(42) | .=. => {} //~ ERROR expected pattern, found `.`
+        //~^ while parsing this or-pattern staring here
+        //~| NOTE expected pattern
+    }
+}
diff --git a/src/test/ui/or-patterns/while-parsing-this-or-pattern.stderr b/src/test/ui/or-patterns/while-parsing-this-or-pattern.stderr
new file mode 100644
index 00000000000..21fece6c64f
--- /dev/null
+++ b/src/test/ui/or-patterns/while-parsing-this-or-pattern.stderr
@@ -0,0 +1,10 @@
+error: expected pattern, found `.`
+  --> $DIR/while-parsing-this-or-pattern.rs:5:20
+   |
+LL |         Some(42) | .=. => {}
+   |         --------   ^ expected pattern
+   |         |
+   |         while parsing this or-pattern staring here
+
+error: aborting due to previous error
+