[PATCH] check -nopie in configure

[Szabolcs Nagy <szabolcs dot nagy at arm dot com>]

since gcc can be built with --enable-default-pie, there
is a -no-pie flag to turn off PIE.

gcc cannot be built as PIE (pr 71934), so the gcc build
system has to detect the -no-pie flag to disable PIE.

historically default pie toolchains used the -nopie flag
(e.g. gentoo hardened), those toolchains cannot build
gcc anymore, so detect -nopie too.

gcc/
2016-07-20  Szabolcs Nagy  <szabolcs.nagy@arm.com>

	* configure.ac: Detect -nopie flag just like -no-pie.
	* configure: Regenerate.

diff --git a/gcc/configure b/gcc/configure
index ed44472..ca16e66 100755
--- a/gcc/configure
+++ b/gcc/configure
@@ -29566,6 +29566,33 @@ fi
 $as_echo "$gcc_cv_no_pie" >&6; }
 if test "$gcc_cv_no_pie" = "yes"; then
   NO_PIE_FLAG="-no-pie"
+else
+  # Check if -nopie works.
+  { $as_echo "$as_me:${as_lineno-$LINENO}: checking for -nopie option" >&5
+$as_echo_n "checking for -nopie option... " >&6; }
+if test "${gcc_cv_nopie+set}" = set; then :
+  $as_echo_n "(cached) " >&6
+else
+  saved_LDFLAGS="$LDFLAGS"
+     LDFLAGS="$LDFLAGS -nopie"
+     cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+int main(void) {return 0;}
+_ACEOF
+if ac_fn_cxx_try_link "$LINENO"; then :
+  gcc_cv_nopie=yes
+else
+  gcc_cv_nopie=no
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+     LDFLAGS="$saved_LDFLAGS"
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $gcc_cv_nopie" >&5
+$as_echo "$gcc_cv_nopie" >&6; }
+  if test "$gcc_cv_nopie" = "yes"; then
+    NO_PIE_FLAG="-nopie"
+  fi
 fi
 
 
diff --git a/gcc/configure.ac b/gcc/configure.ac
index 086d0fc..98ab5cb 100644
--- a/gcc/configure.ac
+++ b/gcc/configure.ac
@@ -6200,6 +6200,19 @@ AC_CACHE_CHECK([for -no-pie option],
    LDFLAGS="$saved_LDFLAGS"])
 if test "$gcc_cv_no_pie" = "yes"; then
   NO_PIE_FLAG="-no-pie"
+else
+  # Check if -nopie works.
+  AC_CACHE_CHECK([for -nopie option],
+    [gcc_cv_nopie],
+    [saved_LDFLAGS="$LDFLAGS"
+     LDFLAGS="$LDFLAGS -nopie"
+     AC_LINK_IFELSE([int main(void) {return 0;}],
+       [gcc_cv_nopie=yes],
+       [gcc_cv_nopie=no])
+     LDFLAGS="$saved_LDFLAGS"])
+  if test "$gcc_cv_nopie" = "yes"; then
+    NO_PIE_FLAG="-nopie"
+  fi
 fi
 AC_SUBST([NO_PIE_FLAG])