> configure.ac: > +AC_REQUIRE([gl_ANSI_CXX]) > +if test "$CXX" != no; then > + dnl On FreeBSD 12, 'c++' defines __cplusplus to 201402, although it does > not > + dnl have the <cuchar> header file from C++11. > + AC_CACHE_CHECK([whether the C++ compiler has <cuchar>], > + [gl_cv_cxxheader_cuchar], > + [AC_LANG_PUSH([C++]) > + AC_COMPILE_IFELSE( > + [AC_LANG_PROGRAM( > + [[#include <cuchar>]], > + [[]]) > + ], > + [gl_cv_cxxheader_cuchar=yes], > + [gl_cv_cxxheader_cuchar=no]) > + AC_LANG_POP([C++]) > + ]) > +else > + gl_cv_cxxheader_cuchar=no > +fi > +AM_CONDITIONAL([CXX_HAVE_CUCHAR], [test $gl_cv_cxxheader_cuchar != no])
This patch caused a serious regression. Namely, in a testdir produced by gnulib-tool, many math function tests fail to link. E.g. test-remainder fails to link because of an unknown function 'remainder'. Why? Because this change causes the "checking whether remainder() can be used without libm" test to report "yes" instead of "no", and likewise for many similar tests, and thus 'test-remainder' gets built without the link option '-lm'. I've reported it as an autoconf bug <https://savannah.gnu.org/support/?110294>. Here is the workaround. 2020-08-18 Bruno Haible <br...@clisp.org> uchar C++ tests: Fix side effect on math modules (regr. 2020-08-17). * modules/uchar-c++-tests (configure.ac): Don't use AC_LANG_PUSH and AC_LANG_POP. diff --git a/modules/uchar-c++-tests b/modules/uchar-c++-tests index 2cbc331..351bdff 100644 --- a/modules/uchar-c++-tests +++ b/modules/uchar-c++-tests @@ -16,15 +16,16 @@ if test "$CXX" != no; then dnl have the <cuchar> header file from C++11. AC_CACHE_CHECK([whether the C++ compiler has <cuchar>], [gl_cv_cxxheader_cuchar], - [AC_LANG_PUSH([C++]) - AC_COMPILE_IFELSE( - [AC_LANG_PROGRAM( - [[#include <cuchar>]], - [[]]) - ], - [gl_cv_cxxheader_cuchar=yes], - [gl_cv_cxxheader_cuchar=no]) - AC_LANG_POP([C++]) + [dnl We can't use AC_LANG_PUSH([C++]) and AC_LANG_POP([C++]) here, due to + dnl an autoconf bug <https://savannah.gnu.org/support/?110294>. + echo '#include <cuchar>' > conftest.cpp + gl_command="$CXX $CXXFLAGS $CPPFLAGS -c conftest.cpp" + if AC_TRY_EVAL([gl_command]); then + gl_cv_cxxheader_cuchar=yes + else + gl_cv_cxxheader_cuchar=no + fi + rm -fr conftest* ]) else gl_cv_cxxheader_cuchar=no
