7 files changed, 45 insertions, 4 deletions
diff --git a/gcc/c-family/ChangeLog b/gcc/c-family/ChangeLog
index 6de6af5..17816a3 100644
--- a/gcc/c-family/ChangeLog
+++ b/gcc/c-family/ChangeLog
@@ -1,3 +1,8 @@
+2015-06-08  Marek Polacek  <polacek@redhat.com>
+
+	PR c/66415
+	* c-format.c (location_from_offset): Return LOC if LINE is null.
+
 2015-06-05  Aldy Hernandez  <aldyh@redhat.com>
 
 	* c-common.h (c_parse_final_cleanups): New prototype.
diff --git a/gcc/c-family/c-format.c b/gcc/c-family/c-format.c
index 719b3a9..564e47b 100644
--- a/gcc/c-family/c-format.c
+++ b/gcc/c-family/c-format.c
@@ -138,9 +138,11 @@ location_from_offset (location_t loc, int offset)
   expanded_location s = expand_location_to_spelling_point (loc);
   int line_width;
   const char *line = location_get_source_line (s, &line_width);
+  if (line == NULL)
+    return loc;
   line += s.column - 1 ;
   line_width -= s.column - 1;
-  unsigned int column = 
+  unsigned int column =
     location_column_from_byte_offset (line, line_width, (unsigned) offset);
 
   return linemap_position_for_loc_and_offset (line_table, loc, column);
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 5537a46..202551f 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2015-06-08  Marek Polacek  <polacek@redhat.com>
+
+	PR c/66415
+	* gcc.dg/cpp/pr66415-1.c: New test.
+	* gcc.dg/cpp/pr66415-2.c: New test.
+
 2015-06-08  Richard Biener  <rguenther@suse.de>
 
 	PR tree-optimization/66422
diff --git a/gcc/testsuite/gcc.dg/cpp/pr66415-1.c b/gcc/testsuite/gcc.dg/cpp/pr66415-1.c
new file mode 100644
index 0000000..922e326
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/cpp/pr66415-1.c
@@ -0,0 +1,9 @@
+/* PR c/66415 */
+/* { dg-do compile } */
+/* { dg-options "-Wformat" } */
+
+void
+fn1 (void)
+{
+  __builtin_printf                                ("xxxxxxxxxxxxxxxxx%dxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"); /* { dg-warning "format" } */
+}
diff --git a/gcc/testsuite/gcc.dg/cpp/pr66415-2.c b/gcc/testsuite/gcc.dg/cpp/pr66415-2.c
new file mode 100644
index 0000000..c168ce9
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/cpp/pr66415-2.c
@@ -0,0 +1,11 @@
+/* PR c/66415 */
+/* { dg-do compile } */
+/* { dg-options "-Wformat" } */
+
+#24
+void
+fn1 (void)
+{
+  __builtin_printf                                ("xxxxxxxxxxxxxxxxx%dxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx");
+  /* { dg-warning "format" "" { target *-*-* } 27 } */
+}
diff --git a/libcpp/ChangeLog b/libcpp/ChangeLog
index 31d3b61..f373dad 100644
--- a/libcpp/ChangeLog
+++ b/libcpp/ChangeLog
@@ -1,3 +1,9 @@
+2015-06-08  Marek Polacek  <polacek@redhat.com>
+
+	PR c/66415
+	* line-map.c (linemap_position_for_loc_and_offset): Remove
+	linemap_assert_fails; reverse conditions.
+
 2015-05-26  Manuel López-Ibáñez  <manu@gcc.gnu.org>
 
 	* line-map.c (LINE_MAP_MAX_COLUMN_NUMBER
diff --git a/libcpp/line-map.c b/libcpp/line-map.c
index 972f66c..d58cad2 100644
--- a/libcpp/line-map.c
+++ b/libcpp/line-map.c
@@ -688,15 +688,17 @@ linemap_position_for_loc_and_offset (struct line_maps *set,
   /* We find the real location and shift it.  */
   loc = linemap_resolve_location (set, loc, LRK_SPELLING_LOCATION, &map);
   /* The new location (loc + offset) should be higher than the first
-     location encoded by MAP.  */
-  if (linemap_assert_fails (MAP_START_LOCATION (map) < loc + offset))
+     location encoded by MAP.
+     FIXME: We used to linemap_assert_fails here and in the if below,
+     but that led to PR66415.  So give up for now.  */
+  if ((MAP_START_LOCATION (map) >= loc + offset))
     return loc;
 
   /* If MAP is not the last line map of its set, then the new location
      (loc + offset) should be less than the first location encoded by
      the next line map of the set.  */
   if (map != LINEMAPS_LAST_ORDINARY_MAP (set))
-    if (linemap_assert_fails (loc + offset < MAP_START_LOCATION (&map[1])))
+    if ((loc + offset >= MAP_START_LOCATION (&map[1])))
       return loc;
 
   offset += SOURCE_COLUMN (map, loc);