From 65fb3b5bf8e71d885a26a5056b09aafea33a05a3 Mon Sep 17 00:00:00 2001
From: jason <jason@138bc75d-0d04-0410-961f-82ee72b054a4>
Date: Fri, 19 May 2017 19:31:52 +0000
Subject: [PATCH] 	* c-warn.c (match_case_to_enum_1): Don't warn about
 enums with no 	enumerators.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@248303 138bc75d-0d04-0410-961f-82ee72b054a4
---
 gcc/c-family/ChangeLog             |  5 +++++
 gcc/c-family/c-warn.c              |  4 ++++
 gcc/testsuite/g++.dg/cpp1z/byte2.C | 13 +++++++++++++
 3 files changed, 22 insertions(+)
 create mode 100644 gcc/testsuite/g++.dg/cpp1z/byte2.C

diff --git a/gcc/c-family/ChangeLog b/gcc/c-family/ChangeLog
index 1db3c331948..4419f207e5c 100644
--- a/gcc/c-family/ChangeLog
+++ b/gcc/c-family/ChangeLog
@@ -1,3 +1,8 @@
+2017-05-19  Jason Merrill  <jason@redhat.com>
+
+	* c-warn.c (match_case_to_enum_1): Don't warn about enums with no
+	enumerators.
+
 2017-05-19  Bernd Edlinger  <bernd.edlinger@hotmail.de>
 
 	* c-format.c (locus): Move out of function scope,
diff --git a/gcc/c-family/c-warn.c b/gcc/c-family/c-warn.c
index e67ffb77bd9..897115612a0 100644
--- a/gcc/c-family/c-warn.c
+++ b/gcc/c-family/c-warn.c
@@ -1069,6 +1069,10 @@ warnings_for_convert_and_check (location_t loc, tree type, tree expr,
 static void
 match_case_to_enum_1 (tree key, tree type, tree label)
 {
+  /* Avoid warning about enums that have no enumerators.  */
+  if (TYPE_VALUES (type) == NULL_TREE)
+    return;
+
   char buf[WIDE_INT_PRINT_BUFFER_SIZE];
 
   if (tree_fits_uhwi_p (key))
diff --git a/gcc/testsuite/g++.dg/cpp1z/byte2.C b/gcc/testsuite/g++.dg/cpp1z/byte2.C
new file mode 100644
index 00000000000..6a395c15530
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/byte2.C
@@ -0,0 +1,13 @@
+// { dg-options "-std=c++17 -Wall" }
+
+#include <cstddef>
+
+bool white_space(std::byte x) {
+  switch (x) {
+  case std::byte{' '}: case std::byte{'\t'}: case std::byte{'\v'}:
+  case std::byte{'\f'}: case std::byte{'\n'}:
+  return true;
+  default:
+    return false;
+  }
+}
-- 
2.11.4.GIT