bug in unwind check for 64bit

bug in unwind check for 64bit

[Riccardo Mottola]

[-- Attachment #1: Type: text/plain, Size: 1514 bytes --]

Hi,

the configure check for unwind

if test x$TARGET = xX86_64; then
     AC_CACHE_CHECK([toolchain supports unwind section type],
         libffi_cv_as_x86_64_unwind_section_type, [
         cat  > conftest1.s << EOF
.text
.globl foo
foo:
jmp bar
.section .eh_frame,"a",@unwind
bar:
EOF

         cat > conftest2.c  << EOF
extern void foo();
int main(){foo();}
EOF

         libffi_cv_as_x86_64_unwind_section_type=no
         # we ensure that we can compile _and_ link an assembly file 
containing an @unwind section
         # since the compiler can support it and not the linker (ie old 
binutils)
         if $CC -Wa,--fatal-warnings $CFLAGS -c conftest1.s > /dev/null 
2>&1 && \
            $CC conftest2.c conftest1.o > /dev/null 2>&1 ; then
             libffi_cv_as_x86_64_unwind_section_type=yes
         fi
         ])
     if test "x$libffi_cv_as_x86_64_unwind_section_type" = xyes; then
         AC_DEFINE(HAVE_AS_X86_64_UNWIND_SECTION_TYPE, 1,
                   [Define if your assembler supports unwind section 
type.])
     fi
fi


is broken, it returns negative even if the option is supported. This 
makes 64bit build on x86 fail (e.g. on solaris 10 in 64 bit).
The problem is that in the linking stage the CFLAGS are not passed, thus 
the first CC line generates a 64 bit object, but then linking is 
attempted in 32bit, which fails. $CFLAGS are needed there too.

The small attached patch fixed this problem, it comes from opencsw, and 
I am giving it back to upstream.

Thank you,

Riccardo

[-- Attachment #2: configure.ac.patch --]
[-- Type: text/x-patch, Size: 547 bytes --]

--- configure.ac.orig	Sun Mar 15 21:45:29 2015
+++ configure.ac	Sun Mar 15 21:59:45 2015
@@ -490,7 +490,7 @@
 	# we ensure that we can compile _and_ link an assembly file containing an @unwind section
 	# since the compiler can support it and not the linker (ie old binutils)
 	if $CC -Wa,--fatal-warnings $CFLAGS -c conftest1.s > /dev/null 2>&1 && \
-           $CC conftest2.c conftest1.o > /dev/null 2>&1 ; then
+           $CC $CFLAGS conftest2.c conftest1.o > /dev/null 2>&1 ; then
 	    libffi_cv_as_x86_64_unwind_section_type=yes
 	fi
 	])