From df6d9e8d1bb955d9cffe3095cc27d4209de1ce33 Mon Sep 17 00:00:00 2001 From: Jelte Fennema-Nio Date: Sun, 29 Mar 2026 13:01:37 +0200 Subject: [PATCH v12 3/4] Add support for C++ extensions with MSVC To build C++ extensions we need support for designated initializers, because PG_MODULE_MAGIC uses it. Designated initializers only got standardized in C++20. In GCC and Clang they also work when using earlier C++ versions, but MSVC really only supports them when its configured to be in C++20 mode or higher. This extends C++11 feature test to also check for designated initializer support. When passing both -pedantic and -Werror even Clang and GCC can fail this new feature test if they're old enough that they don't compile with C++20 by default. So this also changes meson and configure to try C++20 if using C++11 didn't work. Before this patch this such a setup would pass the C++11 check but would then fail to compile test_cplusplusext. --- configure.ac | 13 ++++++---- doc/src/sgml/xfunc.sgml | 5 ++++ meson.build | 26 +++++++++++-------- .../modules/test_cplusplusext/meson.build | 5 ---- 4 files changed, 28 insertions(+), 21 deletions(-) diff --git a/configure.ac b/configure.ac index 2baac5e9da7..e4570a805c6 100644 --- a/configure.ac +++ b/configure.ac @@ -398,17 +398,20 @@ AC_SUBST(have_cxx) if test "$have_cxx" = yes; then -# Detect option needed for C++11 -AC_MSG_CHECKING([for $CXX option to accept ISO C++11]) +# Detect option needed for C++11 with designated initializers. We need +# designated initializers because we use them in many of our headers, including +# in the PG_MODULE_MAGIC definition. +AC_MSG_CHECKING([for $CXX option to accept ISO C++11 with designated initializers]) AC_CACHE_VAL([pgac_cv_prog_cxx_cxx11], [pgac_cv_prog_cxx_cxx11=no pgac_save_CXX=$CXX AC_LANG_PUSH([C++]) -for pgac_arg in '' '-std=gnu++11' '-std=c++11'; do +for pgac_arg in '' '-std=gnu++11' '-std=c++11' '-std=gnu++20' '-std=c++20'; do CXX="$pgac_save_CXX $pgac_arg" AC_COMPILE_IFELSE([AC_LANG_SOURCE([[#if !defined __cplusplus || __cplusplus < 201103L # error "Compiler does not advertise C++11 conformance" -#endif]])], [[pgac_cv_prog_cxx_cxx11=$pgac_arg]]) +#endif +struct S { int x; } s = { .x = 1 };]])], [[pgac_cv_prog_cxx_cxx11=$pgac_arg]]) test x"$pgac_cv_prog_cxx_cxx11" != x"no" && break done AC_LANG_POP([C++]) @@ -416,7 +419,7 @@ CXX=$pgac_save_CXX]) if test x"$pgac_cv_prog_cxx_cxx11" = x"no"; then AC_MSG_RESULT([unsupported]) - AC_MSG_WARN([C++ compiler "$CXX" does not support C++11]) + AC_MSG_WARN([C++ compiler "$CXX" does not support C++11 with designated initializers]) have_cxx=no elif test x"$pgac_cv_prog_cxx_cxx11" = x""; then AC_MSG_RESULT([none needed]) diff --git a/doc/src/sgml/xfunc.sgml b/doc/src/sgml/xfunc.sgml index 70e815b8a2c..6895fe483c1 100644 --- a/doc/src/sgml/xfunc.sgml +++ b/doc/src/sgml/xfunc.sgml @@ -4026,6 +4026,11 @@ extern PgStat_Kind pgstat_register_kind(PgStat_Kind kind, + + You need a C++ compiler that supports C++11 and designated + initializers (GCC and Clang support this in C++11 mode, but MSVC only + supports it in C++20 mode). + All functions accessed by the backend must present a C interface to the backend; these C functions can then call C++ functions. diff --git a/meson.build b/meson.build index 64a5bb888d6..bcad5f4fc01 100644 --- a/meson.build +++ b/meson.build @@ -647,29 +647,33 @@ if not cc.compiles(c11_test, name: 'C11') endif -# Do we need an option to enable C++11? -cxx11_test = ''' +# Do we need an option to enable C++11 and/or designated initializers? We need +# designated initiliazers because we use them in many of our headers, including +# in the PG_MODULE_MAGIC definition. Clang and gcc support designated +# initializers in C++11 mode, but MSVC only supports them in C++20 mode. +cxx_features_test = ''' #if !defined __cplusplus || __cplusplus < 201103L # error "Compiler does not advertise C++11 conformance" #endif +struct S { int x; } s = { .x = 1 }; ''' -if have_cxx and not cxx.compiles(cxx11_test, name: 'C++11') - cxx11_ok = false +if have_cxx and not cxx.compiles(cxx_features_test, name: 'C++11 with designated initializers') + cxx_features_ok = false if cxx.get_id() == 'msvc' - cxx11_test_args = ['/std:c++14'] # oldest version supported + cxx_features_test_args = ['/std:c++20'] else - cxx11_test_args = ['-std=gnu++11', '-std=c++11'] + cxx_features_test_args = ['-std=gnu++11', '-std=c++11', '-std=gnu++20', 'std=c++20'] endif - foreach arg : cxx11_test_args - if cxx.compiles(cxx11_test, name: 'C++11 with @0@'.format(arg), args: [arg]) - cxx11_ok = true + foreach arg : cxx_features_test_args + if cxx.compiles(cxx_features_test, name: 'C++11 with designated initializers with @0@'.format(arg), args: [arg]) + cxx_features_ok = true cxxflags += arg break endif endforeach - if not cxx11_ok - error('C++ compiler does not support C++11') + if not cxx_features_ok + error('C++ compiler does not support C++11 with designated initializers') endif endif diff --git a/src/test/modules/test_cplusplusext/meson.build b/src/test/modules/test_cplusplusext/meson.build index d13210ca593..24a9cf16dca 100644 --- a/src/test/modules/test_cplusplusext/meson.build +++ b/src/test/modules/test_cplusplusext/meson.build @@ -4,11 +4,6 @@ if not have_cxx subdir_done() endif -# Currently not supported, to be fixed. -if cc.get_id() == 'msvc' - subdir_done() -endif - test_cplusplusext_sources = files( 'test_cplusplusext.cpp', ) -- 2.53.0