Patch: PR preprocessor/28165

[Tom Tromey <tromey at redhat dot com>]

This patch fixes PR preprocessor/28165.

The bug here is that _Pragma("GCC system_header") does not warn when 
"#pragma GCC system_header" would have warned.

The problem is that destringize_and_run pushes a new buffer in order
to parse the string argument to _Pragma.  This new buffer has a
non-null 'prev' pointer.  However, the rest of cpp uses 'prev==NULL'
to check to see whether the current file is the outermost.

I fixed this by changing the test for outermost file to look at the
line table's depth instead.  Also I moved this test into a new
function, as I think this is clearer.

Bootstrapped and regression tested on x86 FC6.  New test case
included.

Ok?

Tom

:ADDPATCH preprocessor:

libcpp
2006-12-28  Tom Tromey  <tromey@redhat.com>

	PR preprocessor/28165:
	* internal.h (cpp_in_primary_file): New function.
	* directives.c (do_include_next): Use cpp_in_primary_file.
	(do_pragma_once): Likewise.
	(do_pragma_system_header): Likewise.

gcc/testsuite
2006-12-29  Tom Tromey  <tromey@redhat.com>

	PR preprocessor/28165:
	* gcc.dg/cpp/pr28165.c: New file.

Index: libcpp/internal.h
===================================================================
--- libcpp/internal.h	(revision 120244)
+++ libcpp/internal.h	(working copy)
@@ -1,5 +1,5 @@
 /* Part of CPP library.
-   Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005
+   Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006
    Free Software Foundation, Inc.
 
 This program is free software; you can redistribute it and/or modify it
@@ -488,6 +488,13 @@
 #define CPP_PEDANTIC(PF) CPP_OPTION (PF, pedantic)
 #define CPP_WTRADITIONAL(PF) CPP_OPTION (PF, warn_traditional)
 
+static inline int cpp_in_primary_file (cpp_reader *);
+static inline int
+cpp_in_primary_file (cpp_reader *pfile)
+{
+  return pfile->line_table->depth == 1;
+}
+
 /* In errors.c  */
 extern int _cpp_begin_message (cpp_reader *, int,
 			       source_location, unsigned int);

Index: libcpp/directives.c
===================================================================
--- libcpp/directives.c	(revision 120244)
+++ libcpp/directives.c	(working copy)
@@ -772,7 +780,7 @@
 
   /* If this is the primary source file, warn and use the normal
      search logic.  */
-  if (! pfile->buffer->prev)
+  if (cpp_in_primary_file (pfile))
     {
       cpp_error (pfile, CPP_DL_WARNING,
 		 "#include_next in primary source file");
@@ -1346,7 +1354,7 @@
 static void
 do_pragma_once (cpp_reader *pfile)
 {
-  if (pfile->buffer->prev == NULL)
+  if (cpp_in_primary_file (pfile))
     cpp_error (pfile, CPP_DL_WARNING, "#pragma once in main file");
 
   check_eol (pfile);
@@ -1396,9 +1404,7 @@
 static void
 do_pragma_system_header (cpp_reader *pfile)
 {
-  cpp_buffer *buffer = pfile->buffer;
-
-  if (buffer->prev == 0)
+  if (cpp_in_primary_file (pfile))
     cpp_error (pfile, CPP_DL_WARNING,
 	       "#pragma system_header ignored outside include file");
   else

Index: gcc/testsuite/gcc.dg/cpp/pr28165.c
===================================================================
--- gcc/testsuite/gcc.dg/cpp/pr28165.c	(revision 0)
+++ gcc/testsuite/gcc.dg/cpp/pr28165.c	(revision 0)
@@ -0,0 +1,6 @@
+/* Copyright (C) 2006 Free Software Foundation, Inc.  */
+/* PR preprocessor/28165 */
+
+/* { dg-do preprocess } */
+#pragma GCC system_header   /* { dg-warning "system_header" "ignored" } */
+_Pragma ("GCC system_header")   /* { dg-warning "system_header" "ignored" } */