[PATCH] Don't use -frandom-seed=$@ to build libbacktrace unconditionally (PR bootstrap/54926)

[Jakub Jelinek]

Hi!

Richard noticed that bootstrap with very old GCC as system compiler failed
(as one of the reasons) because -frandom-seed=dwarf.lo etc. was used to
compile the host libbacktrace in stage1.  Non-GCC compilers presumably don't
support that option either.

The following patch fixes it by adding it unconditionally only for target
libbacktrace and otherwise testing, if the option is supported.

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

2012-12-11  Jakub Jelinek  <jakub@redhat.com>

	PR bootstrap/54926
	* Makefile.am (AM_CFLAGS): Remove -frandom-seed=$@.
	* configure.ac: If --with-target-subdir, add -frandom-seed=$@
	to EXTRA_FLAGS unconditionally, otherwise check whether the compiler
	accepts it.
	* Makefile.in: Regenerated.
	* configure: Regenerated.

--- libbacktrace/Makefile.am.jj	2012-12-07 15:13:56.000000000 +0100
+++ libbacktrace/Makefile.am	2012-12-11 12:30:48.498852727 +0100
@@ -34,7 +34,7 @@ ACLOCAL_AMFLAGS = -I .. -I ../config
 AM_CPPFLAGS = -I $(top_srcdir)/../include -I $(top_srcdir)/../libgcc \
 	-I ../libgcc -I ../gcc/include -I $(MULTIBUILDTOP)../../gcc/include
 
-AM_CFLAGS = $(EXTRA_FLAGS) $(WARN_FLAGS) $(PIC_FLAG) -frandom-seed=$@
+AM_CFLAGS = $(EXTRA_FLAGS) $(WARN_FLAGS) $(PIC_FLAG)
 
 noinst_LTLIBRARIES = libbacktrace.la
 
--- libbacktrace/configure.ac.jj	2012-11-14 08:13:38.000000000 +0100
+++ libbacktrace/configure.ac	2012-12-11 12:30:29.466962449 +0100
@@ -98,7 +98,7 @@ AC_SUBST(BACKTRACE_FILE)
 
 EXTRA_FLAGS=
 if test -n "${with_target_subdir}"; then
-  EXTRA_FLAGS=-funwind-tables
+  EXTRA_FLAGS="-funwind-tables -frandom-seed=\$@"
 else
   AC_CACHE_CHECK([for -funwind-tables option],
     [libbacktrace_cv_c_unwind_tables],
@@ -109,9 +109,21 @@ else
        [libbacktrace_cv_c_unwind_tables=yes],
        [libbacktrace_cv_c_unwind_tables=no])
      CFLAGS="$CFLAGS_hold"])
-   if test "$libbacktrace_cv_c_unwind_tables" = "yes"; then
-     EXTRA_FLAGS=-funwind-tables
-   fi
+  if test "$libbacktrace_cv_c_unwind_tables" = "yes"; then
+    EXTRA_FLAGS=-funwind-tables
+  fi
+  AC_CACHE_CHECK([for -frandom-seed=string option],
+    [libbacktrace_cv_c_random_seed_string],
+    [CFLAGS_hold="$CFLAGS"
+     CFLAGS="$CFLAGS -frandom-seed=conftest.lo"
+     AC_COMPILE_IFELSE(
+       [AC_LANG_PROGRAM([], [return 0;])],
+       [libbacktrace_cv_c_random_seed_string=yes],
+       [libbacktrace_cv_c_random_seed_string=no])
+     CFLAGS="$CFLAGS_hold"])
+  if test "$libbacktrace_cv_c_random_seed_string" = "yes"; then
+    EXTRA_FLAGS="$EXTRA_FLAGS -frandom-seed=\$@"
+  fi
 fi
 AC_SUBST(EXTRA_FLAGS)
 
--- libbacktrace/Makefile.in.jj	2012-12-07 15:13:56.000000000 +0100
+++ libbacktrace/Makefile.in	2012-12-11 12:31:05.951752225 +0100
@@ -254,7 +254,7 @@ ACLOCAL_AMFLAGS = -I .. -I ../config
 AM_CPPFLAGS = -I $(top_srcdir)/../include -I $(top_srcdir)/../libgcc \
 	-I ../libgcc -I ../gcc/include -I $(MULTIBUILDTOP)../../gcc/include
 
-AM_CFLAGS = $(EXTRA_FLAGS) $(WARN_FLAGS) $(PIC_FLAG) -frandom-seed=$@
+AM_CFLAGS = $(EXTRA_FLAGS) $(WARN_FLAGS) $(PIC_FLAG)
 noinst_LTLIBRARIES = libbacktrace.la
 libbacktrace_la_SOURCES = \
 	backtrace.h \
--- libbacktrace/configure.jj	2012-11-14 08:13:38.000000000 +0100
+++ libbacktrace/configure	2012-12-11 12:31:19.217675175 +0100
@@ -11491,7 +11491,7 @@ fi
 
 EXTRA_FLAGS=
 if test -n "${with_target_subdir}"; then
-  EXTRA_FLAGS=-funwind-tables
+  EXTRA_FLAGS="-funwind-tables -frandom-seed=\$@"
 else
   { $as_echo "$as_me:${as_lineno-$LINENO}: checking for -funwind-tables option" >&5
 $as_echo_n "checking for -funwind-tables option... " >&6; }
@@ -11521,9 +11521,40 @@ rm -f core conftest.err conftest.$ac_obj
 fi
 { $as_echo "$as_me:${as_lineno-$LINENO}: result: $libbacktrace_cv_c_unwind_tables" >&5
 $as_echo "$libbacktrace_cv_c_unwind_tables" >&6; }
-   if test "$libbacktrace_cv_c_unwind_tables" = "yes"; then
-     EXTRA_FLAGS=-funwind-tables
-   fi
+  if test "$libbacktrace_cv_c_unwind_tables" = "yes"; then
+    EXTRA_FLAGS=-funwind-tables
+  fi
+  { $as_echo "$as_me:${as_lineno-$LINENO}: checking for -frandom-seed=string option" >&5
+$as_echo_n "checking for -frandom-seed=string option... " >&6; }
+if test "${libbacktrace_cv_c_random_seed_string+set}" = set; then :
+  $as_echo_n "(cached) " >&6
+else
+  CFLAGS_hold="$CFLAGS"
+     CFLAGS="$CFLAGS -frandom-seed=conftest.lo"
+     cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main ()
+{
+return 0;
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  libbacktrace_cv_c_random_seed_string=yes
+else
+  libbacktrace_cv_c_random_seed_string=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+     CFLAGS="$CFLAGS_hold"
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libbacktrace_cv_c_random_seed_string" >&5
+$as_echo "$libbacktrace_cv_c_random_seed_string" >&6; }
+  if test "$libbacktrace_cv_c_random_seed_string" = "yes"; then
+    EXTRA_FLAGS="$EXTRA_FLAGS -frandom-seed=\$@"
+  fi
 fi
 
 

	Jakub