Xcode 12：如何链接为独立构建的目标文件

Question

The issue is about linking x86_64 macOS executables statically against libavcodec, libavdevice, etc, which have some object files built against freestanding as they use YASM which isn't able to embed the macOS "tag" in the binary (see Building for macOS, but linking in object file built for free standing for detailed information on that issue).

Everything works fine under Xcode 11.6 - the following messages are here, but they are warnings. With the Xcode 12 update they become an error. How to make them warnings again ? I could not find anything relevant in the ld man page.

ld: in ffmpeg/lib/libavcodec.a(aacencdsp.o), building for macOS, but linking in object file built for free standing, for architecture x86_64

Answer 1

There is no option I have found to revert the error to a warning. Apple has been warning us about this issue for a few releases of XCode now and the warning has become an error.

Until NASM is modified, or we can use some other assembler, the only option that allows me to build and link against the libav libraries in my application is to disable assembly when compiling ffmpeg.

./configure --disable-asm

This works my my case, as the performance of the non-assembly code path is acceptable in my desktop authoring tool. The server-based renderer still uses the assembly code path as it is linux based.

You may have to configure any libaries that you are including in your ffmpeg build to also disable assembly.

Once again, this is an acceptable solution for my case, as the non-assembly code paths are fast enough for my use case.