Fix 69650, bogus line numbers from libcpp

[Bernd Schmidt <bschmidt at redhat dot com>]

This is a case where bogus #line directives can confuse libcpp into 
producing nonsensical line numbers, even leading to a crash later on in LTO.

The following patch moves the test earlier to a point where we can more 
easily recover from the error condition. I should note that I changed 
the raw fprintf (stderr) to a cpp_error call, which is a slight change 
in behaviour (we don't even get to LTO anymore due to erroring out earlier).

Bootstrapped and tested on x86_64-linux (as always including Ada, which 
failed with an earlier version of the patch). Ok?


Bernd

	PR lto/69650
	* directives.c (do_linemarker): Test for file left but not entered
	here.
	* line-map.c (linemap_add): Not here.

	PR lto/69650
	* gcc.dg/pr69650.c: New test.

Index: libcpp/directives.c
===================================================================
--- libcpp/directives.c	(revision 234025)
+++ libcpp/directives.c	(working copy)
@@ -1046,6 +1046,19 @@ do_linemarker (cpp_reader *pfile)
 
   skip_rest_of_line (pfile);
 
+  if (reason == LC_LEAVE)
+    {
+      const line_map_ordinary *from;      
+      if (MAIN_FILE_P (map)
+	  || (new_file
+	      && (from = INCLUDED_FROM (pfile->line_table, map)) != NULL
+	      && filename_cmp (ORDINARY_MAP_FILE_NAME (from), new_file) != 0))
+	{
+	  cpp_error (pfile, CPP_DL_ERROR,
+		     "file \"%s\" left but not entered", new_file);
+	  return;
+	}
+    }
   /* Compensate for the increment in linemap_add that occurs in
      _cpp_do_file_change.  We're currently at the start of the line
      *following* the #line directive.  A separate source_location for this
Index: libcpp/line-map.c
===================================================================
--- libcpp/line-map.c	(revision 234025)
+++ libcpp/line-map.c	(working copy)
@@ -514,43 +514,23 @@ linemap_add (struct line_maps *set, enum
 	 "included", this variable points the map in use right before the
 	 #include "included", inside the same "includer" file.  */
       line_map_ordinary *from;
-      bool error;
-
-      if (MAIN_FILE_P (map - 1))
-	{
-	  /* So this _should_ mean we are leaving the main file --
-	     effectively ending the compilation unit. But to_file not
-	     being NULL means the caller thinks we are leaving to
-	     another file. This is an erroneous behaviour but we'll
-	     try to recover from it. Let's pretend we are not leaving
-	     the main file.  */
-	  error = true;
-          reason = LC_RENAME;
-          from = map - 1;
-	}
-      else
-	{
-	  /* (MAP - 1) points to the map we are leaving. The
-	     map from which (MAP - 1) got included should be the map
-	     that comes right before MAP in the same file.  */
-	  from = INCLUDED_FROM (set, map - 1);
-	  error = to_file && filename_cmp (ORDINARY_MAP_FILE_NAME (from),
-					   to_file);
-	}
 
-      /* Depending upon whether we are handling preprocessed input or
-	 not, this can be a user error or an ICE.  */
-      if (error)
-	fprintf (stderr, "line-map.c: file \"%s\" left but not entered\n",
-		 to_file);
+      linemap_assert (!MAIN_FILE_P (map - 1));
+      /* (MAP - 1) points to the map we are leaving. The
+	 map from which (MAP - 1) got included should be the map
+	 that comes right before MAP in the same file.  */
+      from = INCLUDED_FROM (set, map - 1);
 
       /* A TO_FILE of NULL is special - we use the natural values.  */
-      if (error || to_file == NULL)
+      if (to_file == NULL)
 	{
 	  to_file = ORDINARY_MAP_FILE_NAME (from);
 	  to_line = SOURCE_LINE (from, from[1].start_location);
 	  sysp = ORDINARY_MAP_IN_SYSTEM_HEADER_P (from);
 	}
+      else
+	linemap_assert (filename_cmp (ORDINARY_MAP_FILE_NAME (from),
+				      to_file) == 0);
     }
 
   map->sysp = sysp;
Index: gcc/testsuite/gcc.dg/pr69650.c
===================================================================
--- gcc/testsuite/gcc.dg/pr69650.c	(revision 0)
+++ gcc/testsuite/gcc.dg/pr69650.c	(working copy)
@@ -0,0 +1,5 @@
+/* { dg-do compile } */
+/* { dg-options "-std=gnu99" } */
+
+# 9 "" 2 /* { dg-error "left but not entered" } */
+not_a_type a; /* { dg-error "unknown type" } */