[build] Support --sysroot with Solaris ld

[Rainer Orth <ro at CeBiTec dot Uni-Bielefeld dot DE>]

The Solaris linker recently gained sysroot support.  The following patch
enables that, although there isn't much to do:

* Until recently, ld --help output went to stderr, not being caught by
  gcc/configure's tests which only checked stdout.  However, older ld
  versions still differ here and libtool long has been checking both
  stdout and stderr, so this seems a pretty obvious change to me.

  The only point worth mentioning is that I've guarded the --as-needed
  check for non-GNU ld: before, the native Solaris -z ignore/-z record
  forms were used, now this would use the compat options
  --as-needed/--no-as-needed which occur in the --help output.

* While Solaris ld *does* support --sysroot for gld compatibility, we've
  always preferred the native forms of the options, -z sysroot in this
  case, which the sol2.h part of the patch implements.

Tested in i386-pc-solaris2.12 and sparc-sun-solaris2.12 builds with both
ld and gld, checking that auto-host.h has no unexpected changes.

Also tested with i386-pc-solaris2.12 x sparc-sun-solaris2.12 and
sparc-sun-solaris2.12 x i386-pc-solaris2.12 crosses with both ld (which
has been a cross-linker for quite some time) and gld, checking that -z
sysroot/--sysroot was used as expected.

Ok for mainline?

	Rainer

-- 
-----------------------------------------------------------------------------
Rainer Orth, Center for Biotechnology, Bielefeld University


2017-05-16  Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>

	* configure.ac (gcc_cv_ld_static_dynamic): Also check stderr for
	$gcc_cv_ld --help output.
	(gcc_cv_ld_demangle): Likewise.
	(gcc_cv_ld_eh_frame_hdr): Likewise.
	(gcc_cv_ld_pie): Likewise.
	(gcc_cv_ld_as_needed): Likewise.  Prefer native forms unless $gnu_ld.
	(gcc_cv_ld_buildid): Likewise.
	(gcc_cv_ld_sysroot): Likewise.
	(ld_bndplt_support): Likewise.
	(ld_pushpopstate_support): Likewise.
	* configure: Regenerate.
	* config/sol2.h [!USE_GLD] (SYSROOT_SPEC): Define.

# HG changeset patch
# Parent  75c2ebacfcb74a24e20ed0ec0acd6eeafeff5e86
Support --sysroot with Solaris ld

diff --git a/gcc/config/sol2.h b/gcc/config/sol2.h
--- a/gcc/config/sol2.h
+++ b/gcc/config/sol2.h
@@ -334,6 +334,11 @@ along with GCC; see the file COPYING3.  
 #endif
 
 #ifndef USE_GLD
+/* Prefer native form with Solaris ld.  */
+#define SYSROOT_SPEC "-z sysroot=%R"
+#endif
+
+#ifndef USE_GLD
 /* With Sun ld, use mapfile to enforce direct binding to libgcc_s unwinder.  */
 #define LINK_LIBGCC_MAPFILE_SPEC \
   "%{shared|shared-libgcc:-M %slibgcc-unwind.map}"
diff --git a/gcc/configure.ac b/gcc/configure.ac
--- a/gcc/configure.ac
+++ b/gcc/configure.ac
@@ -3569,8 +3569,8 @@ if test $in_tree_ld = yes ; then
   fi
 elif test x$gcc_cv_ld != x; then
   # Check if linker supports -Bstatic/-Bdynamic option
-  if $gcc_cv_ld --help 2>/dev/null | grep -- -Bstatic > /dev/null \
-     && $gcc_cv_ld --help 2>/dev/null | grep -- -Bdynamic > /dev/null; then
+  if $gcc_cv_ld --help 2>&1 | grep -- -Bstatic > /dev/null \
+     && $gcc_cv_ld --help 2>&1 | grep -- -Bdynamic > /dev/null; then
       gcc_cv_ld_static_dynamic=yes
   else
     case "$target" in
@@ -3614,7 +3614,7 @@ if test x"$demangler_in_ld" = xyes; then
     fi
   elif test x$gcc_cv_ld != x -a x"$gnu_ld" = xyes; then
     # Check if the GNU linker supports --demangle option
-    if $gcc_cv_ld --help 2>/dev/null | grep no-demangle > /dev/null; then
+    if $gcc_cv_ld --help 2>&1 | grep no-demangle > /dev/null; then
       gcc_cv_ld_demangle=yes
     fi
   fi
@@ -4949,7 +4949,7 @@ if test $in_tree_ld = yes ; then
 elif test x$gcc_cv_ld != x; then
   if echo "$ld_ver" | grep GNU > /dev/null; then
     # Check if linker supports --eh-frame-hdr option
-    if $gcc_cv_ld --help 2>/dev/null | grep eh-frame-hdr > /dev/null; then
+    if $gcc_cv_ld --help 2>&1 | grep eh-frame-hdr > /dev/null; then
       gcc_cv_ld_eh_frame_hdr=yes
     fi
   else
@@ -5020,7 +5020,7 @@ if test $in_tree_ld = yes ; then
   fi
 elif test x$gcc_cv_ld != x; then
   # Check if linker supports -pie option
-  if $gcc_cv_ld --help 2>/dev/null | grep -- -pie > /dev/null; then
+  if $gcc_cv_ld --help 2>&1 | grep -- -pie > /dev/null; then
     gcc_cv_ld_pie=yes
     case "$target" in
       *-*-solaris2*)
@@ -5346,19 +5346,19 @@ if test $in_tree_ld = yes ; then
     gcc_cv_ld_as_needed=yes
   fi
 elif test x$gcc_cv_ld != x; then
-	# Check if linker supports --as-needed and --no-as-needed options
-	if $gcc_cv_ld --help 2>/dev/null | grep as-needed > /dev/null; then
-		gcc_cv_ld_as_needed=yes
-	else
-	  case "$target" in
-	    # Solaris 2 ld always supports -z ignore/-z record.
-	    *-*-solaris2*)
-	      gcc_cv_ld_as_needed=yes
-	      gcc_cv_ld_as_needed_option="-z ignore"
-	      gcc_cv_ld_no_as_needed_option="-z record"
-	      ;;
-	  esac
-	fi
+  # Check if linker supports --as-needed and --no-as-needed options
+  if $gcc_cv_ld --help 2>&1 | grep as-needed > /dev/null; then
+    gcc_cv_ld_as_needed=yes
+  fi
+  case "$target:$gnu_ld" in
+    *-*-solaris2*:no)
+      # Solaris 2 ld always supports -z ignore/-z record.  Prefer the native
+      # forms.
+      gcc_cv_ld_as_needed=yes
+      gcc_cv_ld_as_needed_option="-z ignore"
+      gcc_cv_ld_no_as_needed_option="-z record"
+      ;;
+  esac
 fi
 # --as-needed/-z ignore can only be used if libgcc_s.so.1 uses
 # dl_iterate_phdr, i.e. since Solaris 11.
@@ -5598,7 +5598,7 @@ AC_CACHE_CHECK(linker --build-id support
       gcc_cv_ld_buildid=yes
     fi
   elif test x$gcc_cv_ld != x; then
-    if $gcc_cv_ld --help 2>/dev/null | grep build-id > /dev/null; then
+    if $gcc_cv_ld --help 2>&1 | grep build-id > /dev/null; then
       gcc_cv_ld_buildid=yes
     fi
   fi])
@@ -5653,7 +5653,7 @@ AC_CACHE_CHECK(linker --sysroot support,
         gcc_cv_ld_sysroot=yes
       fi
   elif test x$gcc_cv_ld != x; then 
-    if $gcc_cv_ld --help 2>/dev/null | grep sysroot > /dev/null; then
+    if $gcc_cv_ld --help 2>&1 | grep sysroot > /dev/null; then
       gcc_cv_ld_sysroot=yes
     fi
   fi])
@@ -6327,7 +6327,7 @@ if test x"$ld_is_gold" = xno; then
     fi
   elif test x$gcc_cv_ld != x; then
     # Check if linker supports -a bndplt option
-    if $gcc_cv_ld --help 2>/dev/null | grep -- '-z bndplt' > /dev/null; then
+    if $gcc_cv_ld --help 2>&1 | grep -- '-z bndplt' > /dev/null; then
       ld_bndplt_support=yes
     fi
   fi
@@ -6348,7 +6348,7 @@ if test x"$ld_is_gold" = xno; then
     fi
   elif test x$gcc_cv_ld != x; then
     # Check if linker supports --push-state/--pop-state options
-    if $gcc_cv_ld --help 2>/dev/null | grep -- '--push-state' > /dev/null; then
+    if $gcc_cv_ld --help 2>&1 | grep -- '--push-state' > /dev/null; then
       ld_pushpopstate_support=yes
     fi
   fi