Fix ICE in substring locations from macros in header files (PR preprocessor/88257)

PR preprocessor/88257 reports an ICE on gcc.dg/format/pr78304.c
when compiled using g++:

void test (const char *msg)
{
  printf ("size: %" PRIu32 "\n", msg);
}

due to mismatching files (and line maps) between
linemap_resolve_location and expand_location_to_spelling_point
when PRIu32 is defined in a system header.

The root cause is that expand_location_to_spelling_point stops
unwinding locations when it reaches a system header, whereas
linemap_resolve_location can resolve into a system header,
which can lead to locations within get_substring_ranges_for_loc
getting out of sync, and using the wrong line map.

This patch fixes the issue by checking that the files are the
same.

gcc/ChangeLog:
	PR preprocessor/88257
	* input.c (get_substring_ranges_for_loc): Fix indentation.
	Bulletproof against getting a different files back from
	linemap_resolve_location and expand_location_to_spelling_point.

gcc/testsuite/ChangeLog:
	PR preprocessor/88257
	* c-c++-common/Wformat-pr88257.c: New test.
	* c-c++-common/Wformat-pr88257.h: New test header.
	* c-c++-common/empty.h: New test header.

From-SVN: r266671

1 files changed, 6 insertions, 1 deletions

diff --git a/gcc/input.c b/gcc/input.c
index 6ce9782..be1da2c 100644
--- a/gcc/input.c
+++ b/gcc/input.c
@@ -1471,7 +1471,12 @@ get_substring_ranges_for_loc (cpp_reader *pfile,
 	 for start vs finish due to line-length jumps.  */
       if (start_ord_map != final_ord_map
 	  && start_ord_map->to_file != final_ord_map->to_file)
-	  return "start and finish are spelled in different ordinary maps";
+	return "start and finish are spelled in different ordinary maps";
+      /* The file from linemap_resolve_location ought to match that from
+	 expand_location_to_spelling_point.  */
+      if (start_ord_map->to_file != start.file)
+	return "mismatching file after resolving linemap";
+
       location_t start_loc
 	= linemap_position_for_line_and_column (line_table, final_ord_map,
 						start.line, start.column);