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The platform doesn't support undefweak symbols (the kernel module loader fails to load modules containing them), and because creating such modules doesn't involve final linking, only -r linking. The vague-linkage weak defs with abi-v2 mangling that get discarded from floating_to_chars.o because the same comdat section is present in the main executable. But since the alternate mangling is not defined in the main executable, the weak definition decays to a weak undefined symbol in the partially-linked kernel module, and then the kernel module loader barfs. Since our vxworks toolchains have little use for the compat ABI symbols, I thought we could work around this problem by getting rid of them. Absent a configure option to control that, I added one. Regstrapped on x86_64-linux-gnu. Also tested with gcc-13 on arm-, aarch64-, x86- and x86_64-vxworks7r2. Ok to install? PS: for an alternate path to avoid this problem, see also https://sourceware.org/pipermail/binutils/2024-April/133602.html https://sourceware.org/pipermail/binutils/2024-April/133410.html for libstdc++-v3/ChangeLog * acinclude.m4 (GLIBCXX_EXPORT_FLAGS): Split -Wabi=2... (GLIBCXX_ENABLE_WABI): ... here. Control it with newly added --disable-compat-libstdcxx-abi. * configure: Rebuilt. * doc/html/manual/configure.html: Document it. --- libstdc++-v3/acinclude.m4 | 26 ++++++++++++++ libstdc++-v3/configure | 49 ++++++++++++++++++++++----- libstdc++-v3/doc/html/manual/configure.html | 2 + 3 files changed, 67 insertions(+), 10 deletions(-) diff --git a/libstdc++-v3/acinclude.m4 b/libstdc++-v3/acinclude.m4 index 51a08bcc8b1d0..4ef5d5e98c2be 100644 --- a/libstdc++-v3/acinclude.m4 +++ b/libstdc++-v3/acinclude.m4 @@ -707,10 +707,34 @@ AC_DEFUN([GLIBCXX_EXPORT_FLAGS], [ # OPTIMIZE_CXXFLAGS = -O3 -fstrict-aliasing -fvtable-gc AC_SUBST(OPTIMIZE_CXXFLAGS) - WARN_FLAGS="-Wall -Wextra -Wwrite-strings -Wcast-qual -Wabi=2" + WARN_FLAGS="-Wall -Wextra -Wwrite-strings -Wcast-qual" AC_SUBST(WARN_FLAGS) + + GLIBCXX_ENABLE_WABI ]) +dnl +dnl Enable -Wabi=2 if not overridden by --disable-compat-libstdcxx-abi. +dnl +AC_DEFUN([GLIBCXX_ENABLE_WABI], [ + # Default. + WARN_FLAGS_WABI=\ -Wabi=2 + AC_MSG_CHECKING([for --disable-compat-libstdcxx-abi]) + AC_ARG_ENABLE([compat-libstdcxx-abi], + AC_HELP_STRING([--disable-compat-libstdcxx-abi], + [Disable backward-compatibility ABI symbols)]), + [case "$enableval" in + yes) AC_MSG_RESULT(enabled$WARN_FLAGS_WABI) ;; + no) WARN_FLAGS_WABI= + AC_MSG_RESULT(disabled) ;; + *) AC_MSG_RESULT(unsupported) + AC_MSG_ERROR([Unsupported argument to enable/disable compat libstdc++ abi]);; + esac], [ + AC_MSG_RESULT(defaulting to enabled$WARN_FLAGS_WABI) + ]) + + WARN_FLAGS="$WARN_FLAGS$WARN_FLAGS_WABI" +]) dnl dnl All installation directory information is determined here. diff --git a/libstdc++-v3/configure b/libstdc++-v3/configure index 21abaeb077881..8066397b58c2e 100755 --- a/libstdc++-v3/configure +++ b/libstdc++-v3/configure @@ -973,6 +973,7 @@ enable_cet with_gxx_include_dir enable_version_specific_runtime_libs with_toolexeclibdir +enable_compat_libstdcxx_abi with_gcc_major_version_only ' ac_precious_vars='build_alias @@ -1689,6 +1690,8 @@ Optional Features: --enable-version-specific-runtime-libs Specify that runtime libraries should be installed in a compiler-specific directory + --disable-compat-libstdcxx-abi + Disable backward-compatibility ABI symbols) Optional Packages: --with-PACKAGE[=ARG] use PACKAGE [ARG=yes] @@ -12280,7 +12283,7 @@ else lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2 lt_status=$lt_dlunknown cat > conftest.$ac_ext <<_LT_EOF -#line 12283 "configure" +#line 12286 "configure" #include "confdefs.h" #if HAVE_DLFCN_H @@ -12386,7 +12389,7 @@ else lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2 lt_status=$lt_dlunknown cat > conftest.$ac_ext <<_LT_EOF -#line 12389 "configure" +#line 12392 "configure" #include "confdefs.h" #if HAVE_DLFCN_H @@ -16182,7 +16185,7 @@ $as_echo "$glibcxx_cv_atomic_long_long" >&6; } # Fake what AC_TRY_COMPILE does. cat > conftest.$ac_ext << EOF -#line 16185 "configure" +#line 16188 "configure" int main() { typedef bool atomic_type; @@ -16217,7 +16220,7 @@ $as_echo "$glibcxx_cv_atomic_bool" >&6; } rm -f conftest* cat > conftest.$ac_ext << EOF -#line 16220 "configure" +#line 16223 "configure" int main() { typedef short atomic_type; @@ -16252,7 +16255,7 @@ $as_echo "$glibcxx_cv_atomic_short" >&6; } rm -f conftest* cat > conftest.$ac_ext << EOF -#line 16255 "configure" +#line 16258 "configure" int main() { // NB: _Atomic_word not necessarily int. @@ -16288,7 +16291,7 @@ $as_echo "$glibcxx_cv_atomic_int" >&6; } rm -f conftest* cat > conftest.$ac_ext << EOF -#line 16291 "configure" +#line 16294 "configure" int main() { typedef long long atomic_type; @@ -16444,7 +16447,7 @@ $as_echo "mutex" >&6; } # unnecessary for this test. cat > conftest.$ac_ext << EOF -#line 16447 "configure" +#line 16450 "configure" int main() { _Decimal32 d1; @@ -16486,7 +16489,7 @@ ac_compiler_gnu=$ac_cv_cxx_compiler_gnu # unnecessary for this test. cat > conftest.$ac_ext << EOF -#line 16489 "configure" +#line 16492 "configure" template struct same { typedef T2 type; }; @@ -55671,7 +55674,35 @@ $as_echo "$gxx_include_dir" >&6; } # OPTIMIZE_CXXFLAGS = -O3 -fstrict-aliasing -fvtable-gc - WARN_FLAGS="-Wall -Wextra -Wwrite-strings -Wcast-qual -Wabi=2" + WARN_FLAGS="-Wall -Wextra -Wwrite-strings -Wcast-qual" + + + + # Default. + WARN_FLAGS_WABI=\ -Wabi=2 + { $as_echo "$as_me:${as_lineno-$LINENO}: checking for --disable-compat-libstdcxx-abi" >&5 +$as_echo_n "checking for --disable-compat-libstdcxx-abi... " >&6; } + # Check whether --enable-compat-libstdcxx-abi was given. +if test "${enable_compat_libstdcxx_abi+set}" = set; then : + enableval=$enable_compat_libstdcxx_abi; case "$enableval" in + yes) { $as_echo "$as_me:${as_lineno-$LINENO}: result: enabled$WARN_FLAGS_WABI" >&5 +$as_echo "enabled$WARN_FLAGS_WABI" >&6; } ;; + no) WARN_FLAGS_WABI= + { $as_echo "$as_me:${as_lineno-$LINENO}: result: disabled" >&5 +$as_echo "disabled" >&6; } ;; + *) { $as_echo "$as_me:${as_lineno-$LINENO}: result: unsupported" >&5 +$as_echo "unsupported" >&6; } + as_fn_error $? "Unsupported argument to enable/disable compat libstdc++ abi" "$LINENO" 5;; + esac +else + + { $as_echo "$as_me:${as_lineno-$LINENO}: result: defaulting to enabled$WARN_FLAGS_WABI" >&5 +$as_echo "defaulting to enabled$WARN_FLAGS_WABI" >&6; } + +fi + + + WARN_FLAGS="$WARN_FLAGS$WARN_FLAGS_WABI" diff --git a/libstdc++-v3/doc/html/manual/configure.html b/libstdc++-v3/doc/html/manual/configure.html index 346b5d345cd1b..8636b2360d9f0 100644 --- a/libstdc++-v3/doc/html/manual/configure.html +++ b/libstdc++-v3/doc/html/manual/configure.html @@ -108,6 +108,8 @@ then the [time.clock] implementation will use a system call to access the realtime and monotonic clocks, which is significantly slower than the C library's clock_gettime function. +

--disable-compat-libstdcxx-abi

Disables + backward-compatibility ABI symbols.

--enable-libstdcxx-debug

Build separate debug libraries in addition to what is normally built. By default, the debug libraries are compiled with CXXFLAGS='-g3 -O0 -fno-inline' -- Alexandre Oliva, happy hacker https://FSFLA.org/blogs/lxo/ Free Software Activist GNU Toolchain Engineer More tolerance and less prejudice are key for inclusion and diversity Excluding neuro-others for not behaving ""normal"" is *not* inclusive