http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53463
--- Comment #6 from Dodji Seketeli <dodji at gcc dot gnu.org> 2012-06-04 19:20:16 UTC --- Author: dodji Date: Mon Jun 4 19:19:58 2012 New Revision: 188203 URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=188203 Log: PR preprocessor/53463 - Fix system header detection for built-in macro tokens 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 step-up to see where the built-in macro has been expanded, until we see a location that is not for a built-in macro. Then we can check if the resulting location is in a system header or not. Now that we step up to the location of first non-built-in-macro token, it appeared that for testsuite/c-c++-common/dfp/convert-int-saturate.c, G++ then fails to emit the warning in: volatile unsigned int usi; int main () { usi = DEC32_MAX; /* { dg-warning "overflow in implicit constant conversion" } */ ... } Because DEC32_MAX is defined in the system header float.h as a built-in macro: #define DEC32_MAX __DEC32_MAX__ And during the parsing of the assignment expression that should have led to the warning above, input_location is set to the location for the DEC32_MAX, which is actually the location for the built-in __DECL32_MAX_EXP. A possible fix is to use the location of the "=" operator as the default location for assignment expressions. This is what the patch does. I had to adjust a couple of tests to arrange for this. Bootstrapped and tested on x86_64-unknown-linux-gnu against trunk. libcpp/ PR preprocessor/53463 * line-map.c (linemap_location_in_system_header_p): For built-in macro tokens, check the first expansion point location for that is not for a token coming from a built-in macro. gcc/cp/ PR preprocessor/53463 * parser.c (cp_parser_assignment_expression): Use the location for the LHS as the default location for the expression. gcc/testsuite/ PR preprocessor/53463 * g++.dg/cpp/limits.C: New test. * g++.dg/parse/error19.C: Adjust. * g++.dg/warn/Wconversion-real-integer2.C: Likewise. * g++.dg/warn/pr35635.C: Likewise. * g++.old-deja/g++.pt/assign1.C: Likewise. Added: trunk/gcc/testsuite/g++.dg/cpp/limits.C Modified: trunk/gcc/ChangeLog trunk/gcc/cp/parser.c trunk/gcc/testsuite/ChangeLog trunk/gcc/testsuite/g++.dg/parse/error19.C trunk/gcc/testsuite/g++.dg/warn/Wconversion-real-integer2.C trunk/gcc/testsuite/g++.dg/warn/pr35635.C trunk/gcc/testsuite/g++.old-deja/g++.pt/assign1.C trunk/libcpp/ChangeLog trunk/libcpp/line-map.c
