Objective C and Objective C++

[bejolly407]

Please add obj-c and obj-c++ to the list of enabled languages in the next release.

The only GCC-based toolchain that supports Objective C and Objective C++ properly on Windows is the one from MSYS2 MINGW-packages. But I don't want to use a full MSYS2. obj-c and obj-c++ will only add a few files. It will not bloat the w64devkit distribution much.

I'm trying to migrate an old Objective C code base (and might be also Objective C++ as I see the .mm file extension) which is predate Apple. They created their own root class, so I think the GCC runtime is already adequate as the code use no fancy modern features added by Apple.

[Peter0x44]

I can throw a build with that enables in GitHub actions soon.

[Peter0x44]

Here is a w64devkit that has it enabled:

Peter0x44@ec8d1d9

You may download it from github actions using this link, if you are signed in.

https://github.com/Peter0x44/w64devkit/actions/runs/22499170881/artifacts/5696228688

Does it cover your usecase?

[Peter0x44]

I know very little about objc so I tried to generate a hello world that just does an objective C method call.
Most examples you can find online use apple's foundation framework stuff which cannot work here. I tried the following (llm-generated) code:

#include <stdio.h>
#include <objc/runtime.h>

__attribute__((objc_root_class))
@interface MyClass
+ (id)alloc;
- (id)init;
- (void)sayHello;
@end


@implementation MyClass

+ (id)alloc
{
    return class_createInstance(self, 0);
}

- (id)init
{
    return self;
}

- (void)sayHello
{
    printf("Hello from MyClass!\n");
}

@end


int main()
{
    MyClass *obj = [[MyClass alloc] init];

    [obj sayHello];

    return 0;
}

Trying to compile it with:

$ gcc test.m -lobjc
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:\Users\peter\AppData\Local\Temp\cca1fWAC.o:test.m:(.text+0x1f): undefined reference to `__imp_class_createInstance'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(class.o):class.c:(.text+0x8e): undefined reference to `__imp_objc_malloc'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(class.o):class.c:(.text+0xef): undefined reference to `__imp_objc_free'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(class.o):class.c:(.text+0x24a): undefined reference to `__imp_objc_malloc'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(class.o):class.c:(.text+0x3b6): undefined reference to `__imp_objc_calloc'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(class.o):class.c:(.text+0x3fd): undefined reference to `__imp_objc_malloc'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(class.o):class.c:(.text+0x498): undefined reference to `__imp_objc_free'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(init.o):init.c:(.text+0x4a): undefined reference to `__imp_objc_malloc'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(init.o):init.c:(.text+0x64): undefined reference to `__imp_objc_free'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(init.o):init.c:(.text+0x98): undefined reference to `__imp_objc_free'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(init.o):init.c:(.text+0x102): undefined reference to `__imp_objc_getClass'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(init.o):init.c:(.text+0x146): undefined reference to `__imp_sel_registerName'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(init.o):init.c:(.text+0x20b): undefined reference to `__imp_objc_free'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(init.o):init.c:(.text+0x242): undefined reference to `__imp_objc_getClass'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(init.o):init.c:(.text+0x2b9): undefined reference to `__imp_objc_getClass'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(init.o):init.c:(.text+0x366): undefined reference to `__imp_objc_getClass'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(init.o):init.c:(.text+0x38d): undefined reference to `__imp_objc_calloc'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(init.o):init.c:(.text+0x416): undefined reference to `__imp_objc_free'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(init.o):init.c:(.text+0x47a): undefined reference to `__imp_objc_calloc'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(init.o):init.c:(.text+0x5a4): undefined reference to `__imp_objc_getClass'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(init.o):init.c:(.text+0x7b1): undefined reference to `__imp_objc_getClass'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(init.o):init.c:(.text+0x7f9): undefined reference to `__imp_objc_getClass'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(init.o):init.c:(.text+0x8ac): undefined reference to `__imp_objc_getClass'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(init.o):init.c:(.text+0x92d): undefined reference to `__imp_objc_free'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(init.o):init.c:(.text+0x94e): undefined reference to `__imp_objc_getClass'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(init.o):init.c:(.text+0x9e4): undefined reference to `__imp_objc_getClass'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(init.o):init.c:(.text+0xa2d): undefined reference to `__imp_objc_getClass'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(init.o):init.c:(.text+0xb03): undefined reference to `__imp_objc_getClass'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(objc-sync.o):objc-sync.c:(.text+0xd): undefined reference to `__imp_objc_malloc'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(objc-sync.o):objc-sync.c:(.text+0x107): undefined reference to `__imp_objc_malloc'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(protocols.o):protocols.c:(.text+0x2a9): undefined reference to `__imp_objc_lookUpClass'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(protocols.o):protocols.c:(.text+0x31d): undefined reference to `__imp_objc_lookUpClass'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(protocols.o):protocols.c:(.text+0x3b8): undefined reference to `__imp_objc_lookUpClass'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(protocols.o):protocols.c:(.text+0x436): undefined reference to `__imp_objc_lookUpClass'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(protocols.o):protocols.c:(.text+0x46e): undefined reference to `__imp_objc_lookUpClass'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(protocols.o):protocols.c:(.text+0x4bb): more undefined references to `__imp_objc_lookUpClass' follow
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(protocols.o):protocols.c:(.text+0x4ec): undefined reference to `__imp_sel_isEqual'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(protocols.o):protocols.c:(.text+0x55b): undefined reference to `__imp_objc_lookUpClass'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(protocols.o):protocols.c:(.text+0x5f0): undefined reference to `__imp_objc_lookUpClass'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(protocols.o):protocols.c:(.text+0x611): undefined reference to `__imp_objc_lookUpClass'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(protocols.o):protocols.c:(.text+0x651): undefined reference to `__imp_objc_lookUpClass'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(sarray.o):sarray.c:(.text+0x2f): undefined reference to `__imp_objc_free'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(sarray.o):sarray.c:(.text+0x6f): undefined reference to `__imp_objc_free'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(sarray.o):sarray.c:(.text+0x10a): undefined reference to `__imp_objc_malloc'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(sarray.o):sarray.c:(.text+0x148): undefined reference to `__imp_objc_malloc'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(sarray.o):sarray.c:(.text+0x1b0): undefined reference to `__imp_objc_malloc'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(sarray.o):sarray.c:(.text+0x2d4): undefined reference to `__imp_objc_malloc'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(sarray.o):sarray.c:(.text+0x444): undefined reference to `__imp_objc_malloc'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(selector.o):selector.c:(.text+0x3a): more undefined references to `__imp_objc_malloc' follow
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(selector.o):selector.c:(.text+0x7b): undefined reference to `__imp_objc_skip_type_qualifiers'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(selector.o):selector.c:(.text+0x210): undefined reference to `__imp_objc_malloc'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(selector.o):selector.c:(.text+0x273): undefined reference to `__imp_objc_malloc'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(selector.o):selector.c:(.text+0x2fb): undefined reference to `__imp_objc_malloc'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(selector.o):selector.c:(.text+0x4c2): undefined reference to `__imp_objc_calloc'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(selector.o):selector.c:(.text+0x534): undefined reference to `__imp_objc_realloc'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(selector.o):selector.c:(.text+0x567): undefined reference to `__imp_objc_realloc'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(selector.o):selector.c:(.text+0x583): undefined reference to `__imp_objc_free'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(sendmsg.o):sendmsg.c:(.text+0x193): undefined reference to `__imp_objc_sizeof_type'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(sendmsg.o):sendmsg.c:(.text+0x1c9): undefined reference to `__imp_sel_registerName'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(sendmsg.o):sendmsg.c:(.text+0x342): undefined reference to `__imp_sel_registerName'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(sendmsg.o):sendmsg.c:(.text+0x3ec): undefined reference to `__imp_objc_getClass'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(sendmsg.o):sendmsg.c:(.text+0x7d5): undefined reference to `__imp_objc_lookUpClass'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(sendmsg.o):sendmsg.c:(.text+0xa04): undefined reference to `__imp_sel_getName'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(sendmsg.o):sendmsg.c:(.text+0xe54): undefined reference to `__imp_sel_getName'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(sendmsg.o):sendmsg.c:(.text+0xe7f): undefined reference to `__imp_objc_calloc'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(sendmsg.o):sendmsg.c:(.text+0xe98): undefined reference to `__imp_objc_malloc'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(sendmsg.o):sendmsg.c:(.text+0xfb4): undefined reference to `__imp_method_setImplementation'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(thr.o):thr.c:(.text+0x8e): undefined reference to `__imp_objc_malloc'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(thr.o):thr.c:(.text+0xcd): undefined reference to `__imp_objc_free'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(thr.o):thr.c:(.text+0x17c): undefined reference to `__imp_objc_free'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(thr.o):thr.c:(.text+0x250): undefined reference to `__imp_objc_malloc'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(thr.o):thr.c:(.text+0x2ac): undefined reference to `__imp_objc_free'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(thr.o):thr.c:(.text+0x326): undefined reference to `__imp_objc_free'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(thr.o):thr.c:(.text+0x35a): undefined reference to `__imp_objc_msg_lookup'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(thr.o):thr.c:(.text+0x392): undefined reference to `__imp_objc_malloc'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(thr.o):thr.c:(.text+0x3c3): undefined reference to `__imp_objc_free'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(thr.o):thr.c:(.text+0x47c): undefined reference to `__imp_objc_free'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(hash.o):hash.c:(.text+0x54): undefined reference to `__imp_objc_calloc'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(hash.o):hash.c:(.text+0x115): undefined reference to `__imp_objc_free'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(hash.o):hash.c:(.text+0x12a): undefined reference to `__imp_objc_free'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(hash.o):hash.c:(.text+0x1cf): undefined reference to `__imp_objc_free'
C:/Users/peter/Downloads/w64devkit/bin/ld.exe: C:/Users/peter/Downloads/w64devkit/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/libobjc.a(hash.o):hash.c:(.text+0x256): undefined reference to `__imp_objc_calloc'
collect2.exe: error: ld returned 1 exit status

Gives me these undefined references.

The same code builds and runs fine with the gcc-objc archlinux package.

The symbols start with __imp, which means that libobjc.a is probably an import lib?

Perhaps a static libobjc.a doesn't work?
I did see many suspicious -Wattributes warnings when libobjc was being compiled:

2026-02-27T18:55:12.7679698Z #32 41.92 /gcc-15.2.0/libobjc/class.c:386:1: warning: 'objc_setGetUnknownClassHandler' redeclared without dllimport attribute: previous dllimport ignored [-Wattributes]
2026-02-27T18:55:12.7682695Z #32 41.92   386 | objc_setGetUnknownClassHandler (objc_get_unknown_class_handler
2026-02-27T18:55:12.7683438Z #32 41.92       | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
2026-02-27T18:55:12.7684527Z #32 41.92 /gcc-15.2.0/libobjc/class.c:457:1: warning: 'objc_getClass' redeclared without dllimport attribute: previous dllimport ignored [-Wattributes]
2026-02-27T18:55:12.7685837Z #32 41.92   457 | objc_getClass (const char *name)
2026-02-27T18:55:12.7686313Z #32 41.92       | ^~~~~~~~~~~~~
2026-02-27T18:55:12.7687353Z #32 41.92 /gcc-15.2.0/libobjc/class.c:479:1: warning: 'objc_lookUpClass' redeclared without dllimport attribute: previous dllimport ignored [-Wattributes]
2026-02-27T18:55:12.7688509Z #32 41.92   479 | objc_lookUpClass (const char *name)
2026-02-27T18:55:12.7688997Z #32 41.92       | ^~~~~~~~~~~~~~~~

Which seems likely to be related.

[Peter0x44]

I tried with the mingw-w64 package of arch linux, instead of w64devkit.

$ x86_64-w64-mingw32-gcc test.m -lobjc

This worked fine, if the dlls at /usr/x86_64-w64-mingw32/bin/*.dll were copied next to the exe. (including libobjc-4.dll)

Trying instead:

$ x86_64-w64-mingw32-gcc test.m -lobjc -static

Did not work, with almost identical errors to w64devkit.

I suspect the static libobjc for mingw-w64 targets is broken, at least for gcc 15, and no one tests it. Although I am not completely sure of that.

[bejolly407]

I opened libobjc.a in 7-Zip and opened 1.txt (this is my quick method and may be not accurate). I don't think it's an import library.

The import library should be named libobjc.dll.a:

https://packages.msys2.org/packages/mingw-w64-ucrt-x86_64-gcc-objc

For unknown reasons, it's forced to link in dynamic mode and doesn't respect -static. Maybe some obscure licensing issues?

But if the license of the runtime forced it to be linked in dynamic mode, why is there also a static library? I don't get it!

BTW, I forgot that w64devkit is a fully static toolchain just like the one provided by Equation.COM; this is very likely a showstopper

[Peter0x44]

fully static toolchain

This is a choice, not a requirement.

[bejolly407]

fully static toolchain

This is a choice, not a requirement.

I understand. I don't blame w64devkit. One of the reason I use it is because it's small!

[bejolly407]

@skeeto @Peter0x44 Hi, experts. Can you have a look on these?

https://mutablelogic.com/01-runtime/
(scroll down and you will find the GitHub repository: https://github.com/djthorpe/objc/tree/main/src/runtime-gcc).

https://codeberg.org/circusmachina/polar-objc
(Can I build this runtime as a static library? https://codeberg.org/circusmachina/polar-objc/issues/2)

As I only need the Objective C runtime, they seem to be ideal for me.

But I don't know which one is more suitable for w64devkit.

[Peter0x44]

I think you should research that on your own. I'm not interested.

[bejolly407]

I think you should research that on your own. I'm not interested.

OK. The runtime by djthorpe seems to support (and also prefer) static linking. The polar-objc developer has also replied.