Avoid build multiarch if compiler warns about mismatched alias
GCC 8 emits an warning for alias for functions with incompatible types and it is used extensivelly for ifunc resolvers implementations in C (for instance on weak_alias with the internal symbol name to the external one or with the libc_hidden_def to set ifunc for internal usage). This breaks the build when the ifunc resolver is not defined using gcc attribute extensions (HAVE_GCC_IFUNC being 0). Although for all currently architectures that have multiarch support this compiler options is enabled for default, there is still the option where the user might try build glibc with a compiler without support for such extension. In this case this patch just disable the multiarch folder in sysdeps selections. GCC 7 and before still builds IFUNCs regardless of compiler support (although for the lack of attribute support debug information would be optimal). Checked with a build on multiarch support architectures (aarch64, arm, sparc, s390, powerpc, x86_64, i386) with multiarch enable and disable and with GCC 7 and GCC 8. * configure.ac (libc_cv_gcc_incompatbile_alias): New define: indicates whether compiler emits an warning for alias for functions with incompatible types.
This commit is contained in:
Adhemerval Zanella
parent
fe05e1cb6d
commit
8f6f536272
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@ -1,5 +1,9 @@
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2017-10-20 Adhemerval Zanella <adhemerval.zanella@linaro.org>
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* configure.ac (libc_cv_gcc_incompatbile_alias): New define:
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indicates whether compiler emits an warning for alias for
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functions with incompatible types.
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[BZ #22273]
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* sysdeps/unix/sysv/linux/spawni.c (__spawnix): Handle the case where
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the auxiliary process is terminated by a signal before calling _exit
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@ -3996,6 +3996,32 @@ fi
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{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gcc_indirect_function" >&5
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$as_echo "$libc_cv_gcc_indirect_function" >&6; }
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# Check if gcc warns about alias for function with incompatible types.
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{ $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5
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$as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; }
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if ${libc_cv_gcc_incompatible_alias+:} false; then :
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$as_echo_n "(cached) " >&6
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else
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cat > conftest.c <<EOF
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int __redirect_foo (const void *s, int c);
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__typeof (__redirect_foo) *foo_impl (void) __asm__ ("foo");
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__typeof (__redirect_foo) *foo_impl (void)
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{
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return 0;
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}
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extern __typeof (__redirect_foo) foo_alias __attribute__ ((alias ("foo")));
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EOF
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libc_cv_gcc_incompatible_alias=yes
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if ${CC-cc} -Werror -c conftest.c -o conftest.o 1>&5 2>&5 ; then
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libc_cv_gcc_incompatible_alias=no
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fi
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rm -f conftest*
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fi
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{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gcc_incompatible_alias" >&5
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$as_echo "$libc_cv_gcc_incompatible_alias" >&6; }
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if test x"$libc_cv_ld_gnu_indirect_function" != xyes; then
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if test x"$multi_arch" = xyes; then
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as_fn_error $? "--enable-multi-arch support requires assembler and linker support" "$LINENO" 5
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@ -4003,12 +4029,25 @@ if test x"$libc_cv_ld_gnu_indirect_function" != xyes; then
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multi_arch=no
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fi
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fi
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if test x"$libc_cv_gcc_indirect_function" != xyes &&
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test x"$multi_arch" = xyes; then
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{ $as_echo "$as_me:${as_lineno-$LINENO}: WARNING: --enable-multi-arch support recommends a gcc with gnu-indirect-function support.
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if test x"$libc_cv_gcc_indirect_function" != xyes; then
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# GCC 8+ emits a warning for alias with incompatible types and it might
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# fail to build ifunc resolvers aliases to either weak or internal
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# symbols. Disables multiarch build in this case.
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if test x"$libc_cv_gcc_incompatible_alias" == xyes; then
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{ $as_echo "$as_me:${as_lineno-$LINENO}: WARNING: gcc emits a warning for alias between functions of incompatible types" >&5
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$as_echo "$as_me: WARNING: gcc emits a warning for alias between functions of incompatible types" >&2;}
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if test x"$multi_arch" = xyes; then
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as_fn_error $? "--enable-multi-arch support requires a gcc with gnu-indirect-function support" "$LINENO" 5
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fi
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{ $as_echo "$as_me:${as_lineno-$LINENO}: WARNING: Multi-arch is disabled." >&5
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$as_echo "$as_me: WARNING: Multi-arch is disabled." >&2;}
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multi_arch=no
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elif test x"$multi_arch" = xyes; then
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{ $as_echo "$as_me:${as_lineno-$LINENO}: WARNING: --enable-multi-arch support recommends a gcc with gnu-indirect-function support.
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Please use a gcc which supports it by default or configure gcc with --enable-gnu-indirect-function" >&5
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$as_echo "$as_me: WARNING: --enable-multi-arch support recommends a gcc with gnu-indirect-function support.
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Please use a gcc which supports it by default or configure gcc with --enable-gnu-indirect-function" >&2;}
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fi
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fi
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multi_arch_d=
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if test x"$multi_arch" != xno; then
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37
configure.ac
37
configure.ac
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@ -634,6 +634,26 @@ if ${CC-cc} -c conftest.c -o conftest.o 1>&AS_MESSAGE_LOG_FD \
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fi
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rm -f conftest*])
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# Check if gcc warns about alias for function with incompatible types.
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AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types],
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libc_cv_gcc_incompatible_alias, [dnl
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cat > conftest.c <<EOF
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int __redirect_foo (const void *s, int c);
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__typeof (__redirect_foo) *foo_impl (void) __asm__ ("foo");
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__typeof (__redirect_foo) *foo_impl (void)
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{
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return 0;
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}
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extern __typeof (__redirect_foo) foo_alias __attribute__ ((alias ("foo")));
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EOF
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libc_cv_gcc_incompatible_alias=yes
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if ${CC-cc} -Werror -c conftest.c -o conftest.o 1>&AS_MESSAGE_LOG_FD 2>&AS_MESSAGE_LOG_FD ; then
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libc_cv_gcc_incompatible_alias=no
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fi
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rm -f conftest*])
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if test x"$libc_cv_ld_gnu_indirect_function" != xyes; then
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if test x"$multi_arch" = xyes; then
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AC_MSG_ERROR([--enable-multi-arch support requires assembler and linker support])
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@ -641,10 +661,21 @@ if test x"$libc_cv_ld_gnu_indirect_function" != xyes; then
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multi_arch=no
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fi
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fi
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if test x"$libc_cv_gcc_indirect_function" != xyes &&
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test x"$multi_arch" = xyes; then
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AC_MSG_WARN([--enable-multi-arch support recommends a gcc with gnu-indirect-function support.
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if test x"$libc_cv_gcc_indirect_function" != xyes; then
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# GCC 8+ emits a warning for alias with incompatible types and it might
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# fail to build ifunc resolvers aliases to either weak or internal
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# symbols. Disables multiarch build in this case.
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if test x"$libc_cv_gcc_incompatible_alias" == xyes; then
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AC_MSG_WARN([gcc emits a warning for alias between functions of incompatible types])
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if test x"$multi_arch" = xyes; then
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AC_MSG_ERROR([--enable-multi-arch support requires a gcc with gnu-indirect-function support])
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fi
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AC_MSG_WARN([Multi-arch is disabled.])
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multi_arch=no
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elif test x"$multi_arch" = xyes; then
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AC_MSG_WARN([--enable-multi-arch support recommends a gcc with gnu-indirect-function support.
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Please use a gcc which supports it by default or configure gcc with --enable-gnu-indirect-function])
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fi
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fi
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multi_arch_d=
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if test x"$multi_arch" != xno; then
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