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

6 files changed, 69 insertions, 2 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 7597dedf67c..7cda0b4191a 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+2018-11-30  David Malcolm  <dmalcolm@redhat.com>
+
+	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.
+
 2018-11-30  Alexander Monakov  <amonakov@ispras.ru>
 
 	PR gcov-profile/88279
diff --git a/gcc/input.c b/gcc/input.c
index 6ce9782d3a8..be1da2cf471 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);
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 4963b1dd41c..fcc7c8c0a27 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,10 @@
+2018-11-30  David Malcolm  <dmalcolm@redhat.com>
+
+	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.
+
 2018-11-30  Sam Tebbs  <sam.tebbs@arm.com>
 
 	* gcc.target/arm/neon-dotprod-restriction.c: New file.
@@ -10,7 +17,6 @@
 	PR sanitizer/81715
 	* c-c++-common/asan/asan-stack-small.c: New test.
 
->>>>>>> .r266664
 2018-11-30  Richard Biener  <rguenther@suse.de>
 
 	* gcc.dg/gimplefe-34.c: New testcase.
diff --git a/gcc/testsuite/c-c++-common/Wformat-pr88257.c b/gcc/testsuite/c-c++-common/Wformat-pr88257.c
new file mode 100644
index 00000000000..59e4db50847
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/Wformat-pr88257.c
@@ -0,0 +1,23 @@
+/* { dg-options "-Wformat -fdiagnostics-show-caret" } */
+
+#include "Wformat-pr88257.h"
+
+void test (const char *msg)
+{
+  __builtin_printf ("size: %" PRIu32 "\n", msg); /* { dg-warning "expects argument of type" } */
+  /* { dg-begin-multiline-output "" }
+   __builtin_printf ("size: %" PRIu32 "\n", msg);
+                     ^~~~~~~~~              ~~~
+                                            |
+                                            const char *
+     { dg-end-multiline-output "" { target c } } */
+  /* { dg-begin-multiline-output "" }
+ # define PRIu32  "u"
+     { dg-end-multiline-output "" { target c } } */
+  /* { dg-begin-multiline-output "" }
+   __builtin_printf ("size: %" PRIu32 "\n", msg);
+                     ^~~~~~~~~~~~~~~~~~~~~  ~~~
+                                            |
+                                            const char*
+     { dg-end-multiline-output "" { target c++ } } */
+}
diff --git a/gcc/testsuite/c-c++-common/Wformat-pr88257.h b/gcc/testsuite/c-c++-common/Wformat-pr88257.h
new file mode 100644
index 00000000000..c778e935e60
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/Wformat-pr88257.h
@@ -0,0 +1,26 @@
+#pragma GCC system_header
+
+/* Whitespace is significant here, due to line numbering.
+   See the comment below.
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+  End of significant whitespace */
+
+#include "empty.h"
+/* The preceding include ensures a line map starts here, with a line
+   number greater than that of the usage site, to try to trigger
+   an assertion failure.  */
+
+# define PRIu32  "u"
diff --git a/gcc/testsuite/c-c++-common/empty.h b/gcc/testsuite/c-c++-common/empty.h
new file mode 100644
index 00000000000..e69de29bb2d
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/empty.h