The changes in r16-427-g86627faec10da5 do not work for native mingw-w64
builds because the #include with a hardcoded unix-style path doesnt'
work for a native mingw-w64 compiler. This results in configure
detecting that native mingw builds do not support atomic builtins for
the _Atomic_word type, causing non-inline atomics to be used for
__gnu_cxx::__exchange_and_add and __gnu_cxx::__atomic_add, which is an
unintented ABI change (and inconsistent with mingw cross-compilers where
the configure test passes and so enables the inline functions using
atomic builtins).
This attempts to solve the problem by copying the atomic_word.h header
to the current working directory, so it can be included without using an
absolute path.
libstdc++-v3/ChangeLog:
PR libstdc++/125312
* acinclude.m4 (GLIBCXX_ENABLE_ATOMIC_BUILTINS): Copy header
into cwd instead of including it via an absolute path.
* configure: Regenerate.
---
Tested x86_64-linux and bootstrapped on x86_64-mingw-w64 cross.
I can't test it natively. The reporter gave feedback in Bugzilla that
forcing _GLIBCXX_ATOMIC_WORD_BUILTINS=1 in c++config.h does fix the
reproducer.
Once this is fixed on trunk it will need to be backported to gcc-16 and
added to the https://gcc.gnu.org/gcc-16/changes.html release notes.
libstdc++-v3/acinclude.m4 | 15 +++++++++++++--
libstdc++-v3/configure | 23 +++++++++++++++++------
2 files changed, 30 insertions(+), 8 deletions(-)
diff --git a/libstdc++-v3/acinclude.m4 b/libstdc++-v3/acinclude.m4
index 27a434d8a7a5..dfdf96cd09d4 100644
--- a/libstdc++-v3/acinclude.m4
+++ b/libstdc++-v3/acinclude.m4
@@ -3757,6 +3757,15 @@ AC_DEFUN([GLIBCXX_ENABLE_ATOMIC_BUILTINS], [
esac
fi
+ # The $glibcxx_builddir/include/$target/bits/atomic_word.h header is created
+ # by include/Makefile so isn't available during configure. Copy it from the
+ # source dir to $PWD so that we don't include it using an absolute path,
+ # which does not work for win32 native builds (PR libstdc++/125312).
+ if ! $LN_S "${glibcxx_srcdir}/config/${atomic_word_dir}/atomic_word.h" ./
+ then
+ AC_MSG_ERROR([cannot create ./atomic_word.h])
+ fi
+
if test "$atomic_builtins_link_tests" = yes; then
# Do link tests.
@@ -3765,7 +3774,7 @@ AC_DEFUN([GLIBCXX_ENABLE_ATOMIC_BUILTINS], [
AC_CACHE_CHECK([for atomic builtins for _Atomic_word],
glibcxx_cv_atomic_word,
- [AC_TRY_LINK([#include
"${glibcxx_srcdir}/config/$atomic_word_dir/atomic_word.h"],
+ [AC_TRY_LINK([#include "atomic_word.h"],
[_Atomic_word a = 0, b;
b = __atomic_fetch_add(&a, 1, __ATOMIC_ACQ_REL);],
[glibcxx_cv_atomic_word=yes],
@@ -3781,7 +3790,7 @@ AC_DEFUN([GLIBCXX_ENABLE_ATOMIC_BUILTINS], [
cat > conftest.$ac_ext << EOF
[#]line __oline__ "configure"
-[#]include "${glibcxx_srcdir}/config/$atomic_word_dir/atomic_word.h"
+[#]include "atomic_word.h"
int main()
{
_Atomic_word a = 0, b;
@@ -3801,6 +3810,8 @@ EOF
rm -f conftest*
fi
+ rm -f ./atomic_word.h
+
CXXFLAGS="$old_CXXFLAGS"
AC_LANG_RESTORE
diff --git a/libstdc++-v3/configure b/libstdc++-v3/configure
index b51694ecdfbe..cdc912c79896 100755
--- a/libstdc++-v3/configure
+++ b/libstdc++-v3/configure
@@ -16422,6 +16422,15 @@ ac_compiler_gnu=$ac_cv_cxx_compiler_gnu
esac
fi
+ # The $glibcxx_builddir/include/$target/bits/atomic_word.h header is created
+ # by include/Makefile so isn't available during configure. Copy it from the
+ # source dir to $PWD so that we don't include it using an absolute path,
+ # which does not work for win32 native builds (PR libstdc++/125312).
+ if ! $LN_S "${glibcxx_srcdir}/config/${atomic_word_dir}/atomic_word.h" ./
+ then
+ as_fn_error $? "cannot create ./atomic_word.h" "$LINENO" 5
+ fi
+
if test "$atomic_builtins_link_tests" = yes; then
# Do link tests.
@@ -16438,7 +16447,7 @@ else
fi
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */
-#include "${glibcxx_srcdir}/config/$atomic_word_dir/atomic_word.h"
+#include "atomic_word.h"
int
main ()
{
@@ -16468,8 +16477,8 @@ $as_echo "$glibcxx_cv_atomic_word" >&6; }
# Fake what AC_TRY_COMPILE does.
cat > conftest.$ac_ext << EOF
-#line 16471 "configure"
-#include "${glibcxx_srcdir}/config/$atomic_word_dir/atomic_word.h"
+#line 16480 "configure"
+#include "atomic_word.h"
int main()
{
_Atomic_word a = 0, b;
@@ -16495,6 +16504,8 @@ $as_echo "$glibcxx_cv_atomic_word" >&6; }
rm -f conftest*
fi
+ rm -f ./atomic_word.h
+
CXXFLAGS="$old_CXXFLAGS"
ac_ext=c
ac_cpp='$CPP $CPPFLAGS'
@@ -16614,7 +16625,7 @@ $as_echo "mutex" >&6; }
# unnecessary for this test.
cat > conftest.$ac_ext << EOF
-#line 16617 "configure"
+#line 16628 "configure"
int main()
{
_Decimal32 d1;
@@ -16656,7 +16667,7 @@ ac_compiler_gnu=$ac_cv_cxx_compiler_gnu
# unnecessary for this test.
cat > conftest.$ac_ext << EOF
-#line 16659 "configure"
+#line 16670 "configure"
template<typename T1, typename T2>
struct same
{ typedef T2 type; };
@@ -54147,7 +54158,7 @@ $as_echo "$glibcxx_cv_libbacktrace_atomics" >&6; }
CXXFLAGS='-O0 -S'
cat > conftest.$ac_ext << EOF
-#line 54150 "configure"
+#line 54161 "configure"
#include <stddef.h>
int main()
{
--
2.54.0
