[Bug preprocessor/68638] New: [6 Regression] ICE in linemap_macro_map_lookup

["msebor at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68638

            Bug ID: 68638
           Summary: [6 Regression] ICE in linemap_macro_map_lookup
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: preprocessor
          Assignee: unassigned at gcc dot gnu.org
          Reporter: msebor at gcc dot gnu.org
  Target Milestone: ---

The following test case triggers an ICE in linemap_macro_map_lookup, at
libcpp/line-map.c:991 with yesterday's top of trunk.  The test case compiles
fine with GCC 5.1 so this is a regression.

$ cat line-map-ice.c && /build/gcc-trunk-svn/gcc/xgcc -B
/build/gcc-trunk-svn/gcc -O2 -S -Wall -fno-diagnostics-show-caret
line-map-ice.c
typedef union tree_node *tree;

struct ht_identifier {
  const unsigned char *str;
};

struct tree_identifier {
  struct ht_identifier id;
};

union tree_node {
  struct tree_identifier identifier;
};

static int foo (void) {
  tree val;
  return mep_pragma_lex (&val);
}

void bar (void) {
  tree val = 0;
  if (__extension__ ({val;})->identifier.id.str == 0) foo ();
}
line-map-ice.c: In function âfooâ:
line-map-ice.c:17:10: warning: implicit declaration of function
âmep_pragma_lexâ [-Wimplicit-function-declaration]
line-map-ice.c: In function âbarâ:
line-map-ice.c:20:6: internal compiler error: in linemap_macro_map_lookup, at
libcpp/line-map.c:991
0x1795063 linemap_macro_map_lookup
        /home/msebor/scm/fsf/gcc-svn/libcpp/line-map.c:991
0x1794e4e linemap_lookup(line_maps*, unsigned int)
        /home/msebor/scm/fsf/gcc-svn/libcpp/line-map.c:925
0x1795fad linemap_unwind_to_first_non_reserved_loc(line_maps*, unsigned int,
line_map const**)
        /home/msebor/scm/fsf/gcc-svn/libcpp/line-map.c:1629
0x1774164 expand_location_1
        /home/msebor/scm/fsf/gcc-svn/gcc/input.c:159
0x177525d expand_location_to_spelling_point(unsigned int)
        /home/msebor/scm/fsf/gcc-svn/gcc/input.c:751
0x1775283 linemap_client_expand_location_to_spelling_point(unsigned int)
        /home/msebor/scm/fsf/gcc-svn/gcc/input.c:766
0x1796d6c rich_location::add_range(unsigned int, unsigned int, bool)
        /home/msebor/scm/fsf/gcc-svn/libcpp/line-map.c:2011
0x1796e44 rich_location::add_range(source_range, bool)
        /home/msebor/scm/fsf/gcc-svn/libcpp/line-map.c:2024
0x1796b7f rich_location::rich_location(line_maps*, unsigned int)
        /home/msebor/scm/fsf/gcc-svn/libcpp/line-map.c:1961
0x176d9ca warning_at(unsigned int, int, char const*, ...)
        /home/msebor/scm/fsf/gcc-svn/gcc/diagnostic.c:1024
0x1653666 find_explicit_erroneous_behaviour
        /home/msebor/scm/fsf/gcc-svn/gcc/gimple-ssa-isolate-paths.c:400
0x16538ef gimple_ssa_isolate_erroneous_paths
        /home/msebor/scm/fsf/gcc-svn/gcc/gimple-ssa-isolate-paths.c:505
0x16539e2 execute
        /home/msebor/scm/fsf/gcc-svn/gcc/gimple-ssa-isolate-paths.c:556
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