re PR c++/90590 (enumeration value not handled in switch warning for std::ios_base::seek_dir)

PR c++/90590

	* c-warn.c (c_do_switch_warnings): Suppress warning for enumerators
	with reserved names that are in a system header.

	* c-c++-common/pr90590-1.c: New test.
	* c-c++-common/pr90590-1.h: New test.
	* c-c++-common/pr90590-2.c: New test.
	* c-c++-common/pr90590-2.h: New test.

From-SVN: r273980

gcc/ChangeLog

+2019-08-01  Matthew Beliveau  <mbelivea@redhat.com>
+
+	PR c++/90590
+	* c-warn.c (c_do_switch_warnings): Suppress warning for enumerators
+	with reserved names that are in a system header.
+
 2019-08-01  Uroš Bizjak  <ubizjak@gmail.com>
 
 	* config/i386/mmx.md (vec_extractv2si_0): Add (r,x) alternative.

gcc/c-family/c-warn.c

@@ -34,6 +34,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "gcc-rich-location.h"
 #include "gimplify.h"
 #include "c-family/c-indentation.h"
+#include "c-family/c-spellcheck.h"
 #include "calls.h"
 #include "stor-layout.h"
 
@@ -1628,6 +1629,15 @@ c_do_switch_warnings (splay_tree cases, location_t switch_location,
       if (cond && tree_int_cst_compare (cond, value))
 	continue;
 
+      /* If the enumerator is defined in a system header and uses a reserved
+	 name, then we continue to avoid throwing a warning.  */
+      location_t loc = DECL_SOURCE_LOCATION
+	    (TYPE_STUB_DECL (TYPE_MAIN_VARIANT (type)));
+      if (in_system_header_at (loc)
+	  && name_reserved_for_implementation_p
+	      (IDENTIFIER_POINTER (TREE_PURPOSE (chain))))
+	continue;
+
       /* If there is a default_node, the only relevant option is
 	 Wswitch-enum.  Otherwise, if both are enabled then we prefer
 	 to warn using -Wswitch because -Wswitch is enabled by -Wall

gcc/testsuite/ChangeLog

+2019-08-01  Matthew Beliveau  <mbelivea@redhat.com>
+
+	PR c++/90590
+	* c-c++-common/pr90590-1.c: New test.
+	* c-c++-common/pr90590-1.h: New test.
+	* c-c++-common/pr90590-2.c: New test.
+	* c-c++-common/pr90590-2.h: New test.
+
 2019-08-01  Marek Polacek  <polacek@redhat.com>
 
 	PR c++/90805 - detect narrowing in case values.

gcc/testsuite/c-c++-common/pr90590-1.c

+// PR c++/90590
+// { dg-options -Wswitch }
+#include "pr90590-1.h"
+
+void
+g ()
+{
+  enum E e = _A;
+  switch (e) // { dg-bogus "enumeration value '_C' not handled in switch" }
+    {
+    case _A:
+    case _B:
+      break;
+    }
+}

gcc/testsuite/c-c++-common/pr90590-1.h

+#pragma GCC system_header
+enum E { _A, _B, _C };

gcc/testsuite/c-c++-common/pr90590-2.c

+// PR c++/90590
+// { dg-options -Wswitch }
+
+#include "pr90590-2.h"
+
+void
+fn ()
+{
+  switch (c.b) // { dg-bogus "enumeration value" }
+    ;
+}

gcc/testsuite/c-c++-common/pr90590-2.h

+#pragma GCC system_header
+struct {
+  enum { _A } b;
+} c;