From 63397ed786c0feb42f9a29989f8c53fe0c9c07ec Mon Sep 17 00:00:00 2001 From: Jelte Fennema-Nio Date: Fri, 2 Jan 2026 22:31:05 +0100 Subject: [PATCH v7 1/5] Support building C++ extensions with MSVC In 476b35d4e31 a C++ test extension module was added. This test was disabled for MSVC, because it failed to compile it in any C++ version lower than C++20. The reason for that is our usage of designated initializers in PG_MODULE_MAGIC_DATA (which was done in 9324c8c580). Designated initialzers are only part of C++ from the C++20 standard (although clang and gcc implemented support way earlier). This reverts to using positional initializers in PG_MODULE_MAGIC_DATA so that its possible to write C++ extensions in standard C++11. Sadly that means that using designated initializers in C++20 is still not allowed in PG_MODULE_MAGIC_EXT because mixing designated an positional initializers is a C only feature. This restriction for C++ extensions is now documented and tested. --- doc/src/sgml/xfunc.sgml | 6 ++++++ meson.build | 4 ++++ src/include/fmgr.h | 12 +++++++----- .../test_cplusplusext/expected/test_cplusplusext.out | 7 +++++++ src/test/modules/test_cplusplusext/meson.build | 5 ----- .../test_cplusplusext/sql/test_cplusplusext.sql | 3 +++ .../modules/test_cplusplusext/test_cplusplusext.cpp | 2 +- 7 files changed, 28 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/xfunc.sgml b/doc/src/sgml/xfunc.sgml index 70e815b8a2c..143f87a253a 100644 --- a/doc/src/sgml/xfunc.sgml +++ b/doc/src/sgml/xfunc.sgml @@ -1973,6 +1973,12 @@ PG_MODULE_MAGIC_EXT( .name = "my_module_name", .version = "1.2.3" ); + + + In C++ code, use positional arguments instead of designated initializers: + + +PG_MODULE_MAGIC_EXT("my_module_name", "1.2.3"); Subsequently the name and version can be examined via diff --git a/meson.build b/meson.build index df907b62da3..056412890b5 100644 --- a/meson.build +++ b/meson.build @@ -2238,6 +2238,10 @@ if cc.get_id() == 'msvc' '/w24777', # 'function' : format string 'string' requires an argument of type 'type1', but variadic argument number has type 'type2' [like -Wformat] ] + cxxflags_warn += [ + '/wd4200', # nonstandard extension used: zero-sized array in struct/union + ] + cppflags += [ '/DWIN32', '/DWINDOWS', diff --git a/src/include/fmgr.h b/src/include/fmgr.h index eabbc78b280..1ab8749cee1 100644 --- a/src/include/fmgr.h +++ b/src/include/fmgr.h @@ -497,13 +497,15 @@ typedef struct } /* - * Macro to fill a magic block. If any arguments are given, they should - * be field initializers. + * Macro to fill a magic block. If any arguments are given, they should be + * field initializers. These can be designated initialzers, or non-designated + * initializers. If they're non-designated, they are applied after the ABI + * fields. */ #define PG_MODULE_MAGIC_DATA(...) \ { \ - .len = sizeof(Pg_magic_struct), \ - .abi_fields = PG_MODULE_ABI_DATA, \ + sizeof(Pg_magic_struct), \ + PG_MODULE_ABI_DATA, \ __VA_ARGS__ \ } @@ -524,7 +526,7 @@ extern PGDLLEXPORT const Pg_magic_struct *PG_MAGIC_FUNCTION_NAME(void); \ const Pg_magic_struct * \ PG_MAGIC_FUNCTION_NAME(void) \ { \ - static const Pg_magic_struct Pg_magic_data = PG_MODULE_MAGIC_DATA(.name = NULL); \ + static const Pg_magic_struct Pg_magic_data = PG_MODULE_MAGIC_DATA(); \ return &Pg_magic_data; \ } \ extern int no_such_variable diff --git a/src/test/modules/test_cplusplusext/expected/test_cplusplusext.out b/src/test/modules/test_cplusplusext/expected/test_cplusplusext.out index ab0b04b5c5e..25600cfd1b4 100644 --- a/src/test/modules/test_cplusplusext/expected/test_cplusplusext.out +++ b/src/test/modules/test_cplusplusext/expected/test_cplusplusext.out @@ -5,3 +5,10 @@ SELECT test_cplusplus_add(1, 2); 3 (1 row) +SELECT module_name, version FROM pg_get_loaded_modules() + WHERE module_name = 'test_cplusplusext'; + module_name | version +-------------------+--------- + test_cplusplusext | 1.2 +(1 row) + 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', ) diff --git a/src/test/modules/test_cplusplusext/sql/test_cplusplusext.sql b/src/test/modules/test_cplusplusext/sql/test_cplusplusext.sql index a41682417ae..693910ba637 100644 --- a/src/test/modules/test_cplusplusext/sql/test_cplusplusext.sql +++ b/src/test/modules/test_cplusplusext/sql/test_cplusplusext.sql @@ -1,3 +1,6 @@ CREATE EXTENSION test_cplusplusext; SELECT test_cplusplus_add(1, 2); + +SELECT module_name, version FROM pg_get_loaded_modules() + WHERE module_name = 'test_cplusplusext'; diff --git a/src/test/modules/test_cplusplusext/test_cplusplusext.cpp b/src/test/modules/test_cplusplusext/test_cplusplusext.cpp index 435937c00d2..7108e5b1cc5 100644 --- a/src/test/modules/test_cplusplusext/test_cplusplusext.cpp +++ b/src/test/modules/test_cplusplusext/test_cplusplusext.cpp @@ -18,7 +18,7 @@ extern "C" { #include "postgres.h" #include "fmgr.h" -PG_MODULE_MAGIC; +PG_MODULE_MAGIC_EXT("test_cplusplusext", "1.2"); PG_FUNCTION_INFO_V1(test_cplusplus_add); } base-commit: 9b9eaf08ab2dc22c691b22e59f1574e0f1bcc822 -- 2.52.0