From e26e6749fb5638749ed8d73fcb595a11c12f7eb2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Esteban=20K=C3=BCber?= <esteban@kuber.com.ar>
Date: Tue, 23 Jul 2019 16:28:20 -0700
Subject: [PATCH] Always emit trailing slash error

---
 src/libsyntax/parse/unescape_error_reporting.rs |  2 +-
 src/test/ui/parser/issue-62913.rs               |  3 +++
 src/test/ui/parser/issue-62913.stderr           | 16 ++++++++++++++++
 3 files changed, 20 insertions(+), 1 deletion(-)
 create mode 100644 src/test/ui/parser/issue-62913.rs
 create mode 100644 src/test/ui/parser/issue-62913.stderr

diff --git a/src/libsyntax/parse/unescape_error_reporting.rs b/src/libsyntax/parse/unescape_error_reporting.rs
index 71b41161ad8..34af3238fb0 100644
--- a/src/libsyntax/parse/unescape_error_reporting.rs
+++ b/src/libsyntax/parse/unescape_error_reporting.rs
@@ -191,7 +191,7 @@ pub(crate) fn emit_unescape_error(
             handler.span_err(span, "empty character literal")
         }
         EscapeError::LoneSlash => {
-            panic!("lexer accepted unterminated literal with trailing slash")
+            handler.span_err(span, "invalid trailing slash in literal")
         }
     }
 }
diff --git a/src/test/ui/parser/issue-62913.rs b/src/test/ui/parser/issue-62913.rs
new file mode 100644
index 00000000000..cfa19a2a310
--- /dev/null
+++ b/src/test/ui/parser/issue-62913.rs
@@ -0,0 +1,3 @@
+"\u\\"
+//~^ ERROR incorrect unicode escape sequence
+//~| ERROR invalid trailing slash in literal
diff --git a/src/test/ui/parser/issue-62913.stderr b/src/test/ui/parser/issue-62913.stderr
new file mode 100644
index 00000000000..05c5c4d000a
--- /dev/null
+++ b/src/test/ui/parser/issue-62913.stderr
@@ -0,0 +1,16 @@
+error: incorrect unicode escape sequence
+  --> $DIR/issue-62913.rs:1:2
+   |
+LL | "\u\"
+   |  ^^^ incorrect unicode escape sequence
+   |
+   = help: format of unicode escape sequences is `\u{...}`
+
+error: invalid trailing slash in literal
+  --> $DIR/issue-62913.rs:1:5
+   |
+LL | "\u\"
+   |     ^
+
+error: aborting due to 2 previous errors
+