On Tue, Mar 17, 2026 at 5:37 PM Jonathan Wakely <[email protected]> wrote:
> libstdc++-v3/ChangeLog:
>
> PR libstdc++/124554
> * acinclude.m4 (GLIBCXX_CHECK_CSETJMP): Define.
> * config.h.in: Regenerate.
> * configure: Regenerate.
> * configure.ac: Use GLIBCXX_CHECK_CSETJMP.
> * include/c_global/csetjmp: Check new macro.
> ---
>
> For the record, I think something like this would fix PR
> libstdc++/124554 but I'm just going to revert the patch that caused it.
>
You need to also guard exports for longjmp and set_jmp
in libstdc++-v3/src/c++23/std-clib.cc.in.
>
> libstdc++-v3/acinclude.m4 | 22 +++++++++++++
> libstdc++-v3/config.h.in | 3 ++
> libstdc++-v3/configure | 45 +++++++++++++++++++++++++++
> libstdc++-v3/configure.ac | 3 ++
> libstdc++-v3/include/c_global/csetjmp | 2 ++
> 5 files changed, 75 insertions(+)
>
> diff --git a/libstdc++-v3/acinclude.m4 b/libstdc++-v3/acinclude.m4
> index 8dc9e17b214c..23ffaf789724 100644
> --- a/libstdc++-v3/acinclude.m4
> +++ b/libstdc++-v3/acinclude.m4
> @@ -5902,6 +5902,28 @@ AC_LANG_SAVE
> AC_LANG_RESTORE
> ])
>
> +dnl
> +dnl Check whether we can define the contents of <csetjmp>
> +dnl
> +dnl Defines:
> +dnl _GLIBCXX_HAVE_JMP_BUF if setjmp and jmp_buf are available.
> +dnl
> +AC_DEFUN([GLIBCXX_CHECK_CSETJMP], [
> + AC_LANG_SAVE
> + AC_LANG_CPLUSPLUS
> +
> + AC_MSG_CHECKING([for jmp_buf and setjmp in <setjmp.h>])
> + AC_TRY_COMPILE([#include <setjmp.h>],
> + [using ::jmp_buf; using ::setjmp;],
> + [ac_jmp_buf=yes],[ac_jmp_buf=no])
> + AC_MSG_RESULT($ac_jmp_buf)
> + if test "$ac_jmp_buf" = yes; then
> + AC_DEFINE(HAVE_JMP_BUF,1,[Define if jmp_buf is defined in <setjmp.h>])
> + fi
> +
> + AC_LANG_RESTORE
> +])
> +
>
> # Macros from the top-level gcc directory.
> m4_include([../config/gc++filt.m4])
> diff --git a/libstdc++-v3/config.h.in b/libstdc++-v3/config.h.in
> index 4cfb9ba26be4..83e03ea91ed5 100644
> --- a/libstdc++-v3/config.h.in
> +++ b/libstdc++-v3/config.h.in
> @@ -203,6 +203,9 @@
> /* Defined if iswblank exists. */
> #undef HAVE_ISWBLANK
>
> +/* Define if jmp_buf is defined in <setjmp.h> */
> +#undef HAVE_JMP_BUF
> +
> /* Define if LC_MESSAGES is available in <locale.h>. */
> #undef HAVE_LC_MESSAGES
>
> diff --git a/libstdc++-v3/configure b/libstdc++-v3/configure
> index 6713e4504b1c..d05d6befc932 100755
> --- a/libstdc++-v3/configure
> +++ b/libstdc++-v3/configure
> @@ -55330,6 +55330,51 @@ ac_compiler_gnu=$ac_cv_c_compiler_gnu
>
>
>
> +# Whether we can define the contents of <csetjmp>
> +
> +
> + ac_ext=cpp
> +ac_cpp='$CXXCPP $CPPFLAGS'
> +ac_compile='$CXX -c $CXXFLAGS $CPPFLAGS conftest.$ac_ext >&5'
> +ac_link='$CXX -o conftest$ac_exeext $CXXFLAGS $CPPFLAGS $LDFLAGS
> conftest.$ac_ext $LIBS >&5'
> +ac_compiler_gnu=$ac_cv_cxx_compiler_gnu
> +
> +
> + { $as_echo "$as_me:${as_lineno-$LINENO}: checking for jmp_buf and
> setjmp in <setjmp.h>" >&5
> +$as_echo_n "checking for jmp_buf and setjmp in <setjmp.h>... " >&6; }
> + cat confdefs.h - <<_ACEOF >conftest.$ac_ext
> +/* end confdefs.h. */
> +#include <setjmp.h>
> +int
> +main ()
> +{
> +using ::jmp_buf; using ::setjmp;
> + ;
> + return 0;
> +}
> +_ACEOF
> +if ac_fn_cxx_try_compile "$LINENO"; then :
> + ac_jmp_buf=yes
> +else
> + ac_jmp_buf=no
> +fi
> +rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
> + { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_jmp_buf" >&5
> +$as_echo "$ac_jmp_buf" >&6; }
> + if test "$ac_jmp_buf" = yes; then
> +
> +$as_echo "#define HAVE_JMP_BUF 1" >>confdefs.h
> +
> + fi
> +
> + ac_ext=c
> +ac_cpp='$CPP $CPPFLAGS'
> +ac_compile='$CC -c $CFLAGS $CPPFLAGS conftest.$ac_ext >&5'
> +ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS
> conftest.$ac_ext $LIBS >&5'
> +ac_compiler_gnu=$ac_cv_c_compiler_gnu
> +
> +
> +
> # Define documentation rules conditionally.
>
> # See if makeinfo has been installed and is modern enough
> diff --git a/libstdc++-v3/configure.ac b/libstdc++-v3/configure.ac
> index f81dccdeef70..620f6a54f4c2 100644
> --- a/libstdc++-v3/configure.ac
> +++ b/libstdc++-v3/configure.ac
> @@ -666,6 +666,9 @@ GLIBCXX_CHECK_DEBUGGING
> # For std::print
> GLIBCXX_CHECK_STDIO_LOCKING
>
> +# Whether we can define the contents of <csetjmp>
> +GLIBCXX_CHECK_CSETJMP
> +
> # Define documentation rules conditionally.
>
> # See if makeinfo has been installed and is modern enough
> diff --git a/libstdc++-v3/include/c_global/csetjmp
> b/libstdc++-v3/include/c_global/csetjmp
> index 22311a7ee613..038a5228d91b 100644
> --- a/libstdc++-v3/include/c_global/csetjmp
> +++ b/libstdc++-v3/include/c_global/csetjmp
> @@ -44,6 +44,7 @@
> #endif
>
> #include <bits/c++config.h>
> +#if _GLIBCXX_HAVE_JMP_BUF
> #include <setjmp.h>
>
> // Get rid of those macros defined in <setjmp.h> in lieu of real
> functions.
> @@ -60,4 +61,5 @@ namespace std
> using ::longjmp;
> } // namespace std
>
> +#endif // _GLIBCXX_HAVE_JMP_BUF
> #endif
> --
> 2.53.0
>
>
