meson/docs/markdown/Platform-notes.md

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short-description: Notes and known issues for specific platforms ...

Platform notes

This page collects information that is specific to a platform or to a toolchain.

macOS deployment target

Programs can be compiled for older macOS versions than the one they are compiled on. The version of the build machine therefore does not tell which functions are available when the program runs.

The deployment target is chosen by the compiler. Either set the MACOSX_DEPLOYMENT_TARGET environment variable before running Meson, or pass -mmacosx-version-min in both the compile and the link arguments, for example in a native file:

[built-in options]
c_args = ['-mmacosx-version-min=10.11']
c_link_args = ['-mmacosx-version-min=10.11']

The checks that Meson runs use the same arguments, so they see the deployment target.

When detecting a function with compiler.has_function(), specify the header that declares it in the prefix argument. For example, open_memstream was introduced in macOS 10.13. When building on macOS 10.13 for macOS 10.11, the following check correctly reports the function as missing:

cc.has_function('open_memstream', prefix : '#include <stdio.h>')

Without the header, the check lacks the availability information and incorrectly reports the function as available.

QNX

Meson can detect and use qcc and q++, the C and C++ compiler drivers shipped with the QNX Software Development Platform (SDP). For cross compilation, point the [binaries] section of the cross file at qcc and q++, including the required -V target selector, and set system = 'qnx' in [host_machine]:

[binaries]
c = ['qcc', '-Vgcc_ntoaarch64le']
cpp = ['q++', '-Vgcc_ntoaarch64le']

[host_machine]
system = 'qnx'
cpu_family = 'aarch64'
cpu = 'aarch64'
endian = 'little'

The following limitations apply:

1. ThinLTO incremental cache does not work. -Db_thinlto_cache=true raises an error at configure time, while -Db_lto=true is unaffected.
2. Alternate linker selection is not supported. Setting c_ld or cpp_ld (for example to lld or gold) raises an error.
3. If a header is deleted, stale entries remain in the dependency files, because -MP does not emit phony header rules. A clean build is needed to recover.
4. There is no static sanitizer runtime, so -static-libasan is rejected and only the shared runtime can be linked.
5. The available sanitizers depend on the SDP version. SDP 7.1 only provides libubsan, so -Db_sanitize=address and -Db_sanitize=leak fail to link there. SDP 8.0 adds asan and lsan. -Db_sanitize=undefined works on both, and tsan is not available on either.
6. C++20 named modules do not work. With SDP 8.0, -fmodules-ts compiles but silently ignores .cppm and .ixx files. With SDP 7.1, -fmodules-ts is rejected for C++ sources. Plain -fmodules is rejected on both. This only affects projects that enable modules through cpp_args.
7. Relinking is avoided for unchanged shared libraries only on native QNX builds. When cross compiling to QNX, shared libraries are always relinked.