[PATCH 2/2] Better system header location detection for built-in macro tokens

[Dodji Seketeli <dodji at redhat dot com>]

Hello,

The location for a built-in macro token is BUILTIN_LOCATION.  When we
see that location value, we cannot know if that token was used in a
system header or not.  And that can trigger some unwanted warnings on
e.g, the use of __LONG_LONG_MAX__ built-in macro in system headers
when we compile with -pedantic, like in the test case accompanying
this patch.

In that case, I think we ought to look at the location for the
expansion point of the built-in macro instead.

Bootstrapped and tested on x86_64-unknown-linux-gnu against trunk.

libcpp/

	* line-map.c (linemap_location_in_system_header_p): Check
	expansion point location for built-in macro tokens.

gcc/testsuite/

	* g++.dg/cpp/limits.C: New test.
---
 gcc/testsuite/g++.dg/cpp/limits.C |   21 +++++++++++++++++++++
 libcpp/line-map.c                 |   18 ++++++++++++++----
 2 files changed, 35 insertions(+), 4 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/cpp/limits.C

diff --git a/gcc/testsuite/g++.dg/cpp/limits.C b/gcc/testsuite/g++.dg/cpp/limits.C
new file mode 100644
index 0000000..b64e1e2
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp/limits.C
@@ -0,0 +1,21 @@
+// { dg-options "-pedantic" }
+// { dg-do compile }
+
+#include <limits>
+
+// Compiling this with -pedantic was wrongly triggering this error:
+// libstdc++-v3/include/limits:1269:45: warning : use of C++0x long long integer constant [-Wlong-long]
+//       min() _GLIBCXX_USE_NOEXCEPT { return -__LONG_LONG_MAX__ - 1; }
+//                                             ^
+// libstdc++-v3/include/limits:1272:44: warning : use of C++0x long long integer constant [-Wlong-long]
+//       max() _GLIBCXX_USE_NOEXCEPT { return __LONG_LONG_MAX__; }
+//                                            ^
+// libstdc++-v3/include/limits:1342:44: warning : use of C++0x long long integer constant [-Wlong-long]
+//       max() _GLIBCXX_USE_NOEXCEPT { return __LONG_LONG_MAX__ * 2ULL + 1
+//                                            ^
+
+int
+main ()
+{
+    return 0;
+}
diff --git a/libcpp/line-map.c b/libcpp/line-map.c
index 6e514e5..5a2ca0f 100644
--- a/libcpp/line-map.c
+++ b/libcpp/line-map.c
@@ -754,12 +754,22 @@ linemap_location_in_system_header_p (struct line_maps *set,
 				     source_location location)
 {
   const struct line_map *map = NULL;
-
-  location =
+  source_location loc =
     linemap_resolve_location (set, location, LRK_SPELLING_LOCATION, &map);
 
-  if (location < RESERVED_LOCATION_COUNT)
-    return false;
+  if (loc < RESERVED_LOCATION_COUNT)
+    {
+      /* Maybe LOCATION is for a token that comes from the expansion
+	 of a built-in macro.  In that case, we cannot know from its
+	 spelling location (which is thus a reserved location) where
+	 exactly the token is located.  So let's see where that
+	 built-in macro has been expanded, instead.  */
+      loc = linemap_resolve_location (set, location,
+				      LRK_MACRO_EXPANSION_POINT,
+				      &map);
+      if (loc < RESERVED_LOCATION_COUNT)
+	return false;
+    }
 
   return LINEMAP_SYSP (map);
 }
-- 
		Dodji