libstdc++: Add a test for <version> FTM redefinitions

This test detects redefinitions by compiling stdc++.h and <version>, by
disabling the system_header pragma on the latter, to allow warnings in
it.  Thanks Patrick Palka for the suggestion.

libstdc++-v3/ChangeLog:

	* testsuite/17_intro/versionconflict.cc: New test.
	* include/std/version: Allow disabling the system_header pragma
	via _GLIBCXX_TESTING_SYSHDR.

diff --git a/libstdc++-v3/include/std/version b/libstdc++-v3/include/std/version
index cdd24248c57cdf2cb8ea3b2ea6ede5ffb280e51a..1069bc6c9f6f8d933050c1a4118201c843b057a3 100644 (file)
--- a/libstdc++-v3/include/std/version
+++ b/libstdc++-v3/include/std/version
@@ -30,7 +30,10 @@
 #ifndef _GLIBCXX_VERSION_INCLUDED
 #define _GLIBCXX_VERSION_INCLUDED
 
-#pragma GCC system_header
+// To facilitate testsuite/17_intro/versionconflict.cc
+#ifndef _GLIBCXX_TESTING_SYSHDR
+# pragma GCC system_header
+#endif
 
 #include <bits/c++config.h>
 

diff --git a/libstdc++-v3/testsuite/17_intro/versionconflict.cc b/libstdc++-v3/testsuite/17_intro/versionconflict.cc
new file mode 100644 (file)
index 0000000..6c21298
--- /dev/null
+++ b/libstdc++-v3/testsuite/17_intro/versionconflict.cc
@@ -0,0 +1,7 @@
+// { dg-do preprocess }
+// { dg-additional-options "-Werror" }
+
+// Test for redefinitions of FTMs using bits/stdc++.h.
+#define _GLIBCXX_TESTING_SYSHDR
+#include <bits/stdc++.h>
+#include <version>