[PATCHv2,09/12] gcc/4.7: add patch to warn about unsafe header paths

diff --git a/package/gcc/4.7.4/910-gcc-poison-system-directories.patch b/package/gcc/4.7.4/910-gcc-poison-system-directories.patch
new file mode 100644
index 0000000..bc2d5c6
--- /dev/null
+++ b/package/gcc/4.7.4/910-gcc-poison-system-directories.patch
@@ -0,0 +1,207 @@ 
+From 160397ef3c3331099af028f1b8d3e085b07d88ad Mon Sep 17 00:00:00 2001
+From: Khem Raj <raj.khem@gmail.com>
+Date: Fri, 29 Mar 2013 08:59:00 +0400
+Subject: [PATCH 16/35] gcc: poison-system-directories
+
+Adapted to Buildroot and gcc 4.7.4 by Thomas Petazzoni, especially the
+addition of the BR_COMPILER_PARANOID_UNSAFE_PATH environment variable.
+
+Signed-off-by: Khem Raj <raj.khem@gmail.com>
+Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
+
+Upstream-Status: Inappropriate [distribution: codesourcery]
+---
+ gcc/Makefile.in     |    2 +-
+ gcc/common.opt      |    4 ++++
+ gcc/config.in       |    6 ++++++
+ gcc/configure       |   20 ++++++++++++++++++--
+ gcc/configure.ac    |   10 ++++++++++
+ gcc/doc/invoke.texi |    9 +++++++++
+ gcc/gcc.c           |    2 ++
+ gcc/incpath.c       |   19 +++++++++++++++++++
+ 8 files changed, 69 insertions(+), 3 deletions(-)
+
+Index: b/gcc/common.opt
+===================================================================
+--- a/gcc/common.opt
++++ b/gcc/common.opt
+@@ -585,6 +585,10 @@
+ Common Var(warn_padded) Warning
+ Warn when padding is required to align structure members
+ 
++Wpoison-system-directories
++Common Var(flag_poison_system_directories) Init(1) Warning
++Warn for -I and -L options using system directories if cross compiling
++
+ Wshadow
+ Common Var(warn_shadow) Warning
+ Warn when one local variable shadows another
+Index: b/gcc/config.in
+===================================================================
+--- a/gcc/config.in
++++ b/gcc/config.in
+@@ -144,6 +144,12 @@
+ #endif
+ 
+ 
++/* Define to warn for use of native system header directories */
++#ifndef USED_FOR_TARGET
++#undef ENABLE_POISON_SYSTEM_DIRECTORIES
++#endif
++
++
+ /* Define if you want all operations on RTL (the basic data structure of the
+    optimizer and back end) to be checked for dynamic type safety at runtime.
+    This is quite expensive. */
+Index: b/gcc/configure
+===================================================================
+--- a/gcc/configure
++++ b/gcc/configure
+@@ -918,6 +918,7 @@
+ with_system_zlib
+ enable_maintainer_mode
+ enable_version_specific_runtime_libs
++enable_poison_system_directories
+ enable_plugin
+ enable_libquadmath_support
+ with_linker_hash_style
+@@ -1632,6 +1633,8 @@
+   --enable-version-specific-runtime-libs
+                           specify that runtime libraries should be installed
+                           in a compiler-specific directory
++  --enable-poison-system-directories
++                          warn for use of native system header directories
+   --enable-plugin         enable plugin support
+   --disable-libquadmath-support
+                           disable libquadmath support for Fortran
+@@ -27186,6 +27189,19 @@
+ fi
+ 
+ 
++# Check whether --enable-poison-system-directories was given.
++if test "${enable_poison_system_directories+set}" = set; then :
++  enableval=$enable_poison_system_directories;
++else
++  enable_poison_system_directories=no
++fi
++
++if test "x${enable_poison_system_directories}" = "xyes"; then
++
++$as_echo "#define ENABLE_POISON_SYSTEM_DIRECTORIES 1" >>confdefs.h
++
++fi
++
+ # Substitute configuration variables
+ 
+ 
+Index: b/gcc/configure.ac
+===================================================================
+--- a/gcc/configure.ac
++++ b/gcc/configure.ac
+@@ -5037,6 +5037,16 @@
+                 [specify that runtime libraries should be
+                  installed in a compiler-specific directory])])
+ 
++AC_ARG_ENABLE([poison-system-directories],
++             AS_HELP_STRING([--enable-poison-system-directories],
++                            [warn for use of native system header directories]),,
++             [enable_poison_system_directories=no])
++if test "x${enable_poison_system_directories}" = "xyes"; then
++  AC_DEFINE([ENABLE_POISON_SYSTEM_DIRECTORIES],
++           [1],
++           [Define to warn for use of native system header directories])
++fi
++
+ # Substitute configuration variables
+ AC_SUBST(subdirs)
+ AC_SUBST(srcdir)
+Index: b/gcc/doc/invoke.texi
+===================================================================
+--- a/gcc/doc/invoke.texi
++++ b/gcc/doc/invoke.texi
+@@ -260,6 +260,7 @@
+ -Woverlength-strings  -Wpacked  -Wpacked-bitfield-compat  -Wpadded @gol
+ -Wparentheses  -Wpedantic-ms-format -Wno-pedantic-ms-format @gol
+ -Wpointer-arith  -Wno-pointer-to-int-cast @gol
++-Wno-poison-system-directories @gol
+ -Wredundant-decls @gol
+ -Wreturn-type  -Wsequence-point  -Wshadow @gol
+ -Wsign-compare  -Wsign-conversion  -Wstack-protector @gol
+@@ -3880,6 +3881,14 @@
+  for most targets, it is made up of code and thus requires the stack
+  to be made executable in order for the program to work properly.
+ 
++@item -Wno-poison-system-directories
++@opindex Wno-poison-system-directories
++Do not warn for @option{-I} or @option{-L} options using system
++directories such as @file{/usr/include} when cross compiling.  This
++option is intended for use in chroot environments when such
++directories contain the correct headers and libraries for the target
++system rather than the host.
++
+ @item -Wfloat-equal
+ @opindex Wfloat-equal
+ @opindex Wno-float-equal
+Index: b/gcc/gcc.c
+===================================================================
+--- a/gcc/gcc.c
++++ b/gcc/gcc.c
+@@ -674,6 +674,8 @@
+     %{flto} %{flto=*} %l " LINK_PIE_SPEC \
+    "%X %{o*} %{e*} %{N} %{n} %{r}\
+     %{s} %{t} %{u*} %{z} %{Z} %{!nostdlib:%{!nostartfiles:%S}}\
++    %{Wno-poison-system-directories:--no-poison-system-directories}\
++    %{Werror=poison-system-directories:--error-poison-system-directories}\
+     %{static:} %{L*} %(mfwrap) %(link_libgcc) %o\
+     %{fopenmp|ftree-parallelize-loops=*:%:include(libgomp.spec)%(link_gomp)}\
+     %{fgnu-tm:%:include(libitm.spec)%(link_itm)}\
+@@ -3907,6 +3909,12 @@
+       gcc_assert (!compare_debug_opt);
+     }
+ 
++  temp = getenv("BR_COMPILER_PARANOID_UNSAFE_PATH");
++  if (temp && strlen(temp) > 0)
++    {
++      save_switch("-Werror=poison-system-directories", 0, NULL, false);
++    }
++
+   /* Set up the search paths.  We add directories that we expect to
+      contain GNU Toolchain components before directories specified by
+      the machine description so that we will find GNU components (like
+Index: b/gcc/incpath.c
+===================================================================
+--- a/gcc/incpath.c
++++ b/gcc/incpath.c
+@@ -30,6 +30,7 @@
+ #include "intl.h"
+ #include "incpath.h"
+ #include "cppdefault.h"
++#include "diagnostic-core.h"
+ 
+ /* Microsoft Windows does not natively support inodes.
+    VMS has non-numeric inodes.  */
+@@ -373,6 +374,24 @@
+ 	}
+       fprintf (stderr, _("End of search list.\n"));
+     }
++
++#ifdef ENABLE_POISON_SYSTEM_DIRECTORIES
++  if (flag_poison_system_directories)
++    {
++       struct cpp_dir *p;
++
++       for (p = heads[QUOTE]; p; p = p->next)
++         {
++          if ((!strncmp (p->name, "/usr/include", 12))
++              || (!strncmp (p->name, "/usr/local/include", 18))
++              || (!strncmp (p->name, "/usr/X11R6/include", 18)))
++            warning (OPT_Wpoison_system_directories,
++                     "include location \"%s\" is unsafe for "
++                     "cross-compilation",
++                     p->name);
++         }
++    }
++#endif
+ }
+ 
+ /* Use given -I paths for #include "..." but not #include <...>, and