Summary:
Issue reported by @ryandesign and @MarcusCalhoun-Lopez.
CMake doesn't support spaces in flags. This caused older versions of gcc to
ignore the unknown flag "-z noexecstack" on MacOS since it was interpreted as a
single flag, not two separate flags. Then, during compilation it was treated as
"-z" "noexecstack", which was correctly forwarded to the linker. But the MacOS
linker does not support `-z noexecstack` so compilation failed.
The fix is to use `-Wl,-z,noexecstack`. This is never misinterpreted by a
compiler. However, not all compilers support this syntax to forward flags to the
linker. To fix this issue, we check if all the relevant `noexecstack` flags have
been successfully set, and if they haven't we disable assembly.
See also PR#4056 and PR#4061. I decided to go a different route because this is
simpler. It might not successfully set these flags on some compilers, but in that
case it also disables assembly, so they aren't required.
Test Plan:
```
mkdir build-cmake
cmake ../build/cmake/CMakeLists.txt
make -j
```
See that the linker flag is successfully detected & that assembly is enabled.
Run the same commands on MacOS which doesn't support `-Wl,-z,noexecstack` and see
that everything compiles and that `LD_FLAG_WL_Z_NOEXECSTACK` and
`ZSTD_HAS_NOEXECSTACK` are both false.
CMake warns on the current minimum requirement (3.5). Update to 3.10.
This means support is still available for the default on Ubuntu 18.04, which
exited LTS standard in April of 2023.
[draft]
Meson always returns -pthread in dependency('threads') on non-MSVC
compilers. On Windows we use Windows threading primitives, so we don't
need this. Avoid adding -pthread to libzstd's link flags, either as a
Meson subproject or via pkg-config Libs.private, so the application
doesn't inadvertently depend on winpthreads.
Add a Meson MinGW cross-compile CI test that checks for this. It turns
out that pzstd fails to build in that environment, so have the test
skip building contrib for now.
Document that the `ZSTD_BUILD_{SHARED,STATIC}` take precedence over `BUILD_SHARED_LIBS` when exactly one is ON.
Thanks to @teo-tsirpanis for pointing out the potentially confusing behavior.
* Make a variable `PublicHeaders` for Zstd's public headers
* Add `PublicHeaders` to `Headers`, which was missing
* Only export `${LIBRARY_DIR}` publicly, not `common/`
* Switch the `target_include_directories()` to `INTERFACE` because zstd uses relative includes internally, so doesn't need any include directories to build
* Switch installation to use the `PublicHeaders` variable, and test that the right headers are installed
If both `ZSTD_BUILD_SHARED` and `ZSTD_BUILD_STATIC` are set, then cmake exports the libraries `libzstd_shared` and `libzstd_static` only.
It does not export `libzstd`, which is only exported when exactly one of `ZSTD_BUILD_SHARED` and `ZSTD_BUILD_STATIC` is set.
This PR exports `libzstd` in that case, based on the value of the standard CMake variable [`BUILD_SHARED_LIBS`](https://cmake.org/cmake/help/latest/variable/BUILD_SHARED_LIBS.html).
This ensures that `libzstd` can always be used to refer to the exported zstd library, since the build errors if neither `ZSTD_BUILD_SHARED` nor `ZSTD_BUILD_STATIC` are set.
I tested all the possible combinations of `ZSTD_BUILD_SHARED`, `ZSTD_BUILD_STATIC`, and `BUILD_SHARED_LIBS` and they always worked as expected:
* If only exactly one of `ZSTD_BUILD_SHARED` and `ZSTD_BUILD_STATIC` is set, that is used as `libzstd`.
* Otherwise, libzstd is set based on `BUILD_SHARED_LIBS`.
Fixes#3859.
note: we probably don't want to maintain VS2008 solution anymore.
Its successor VS2010 is > 10 years old,
which is more or less the limit after which we can stop supporting old compilers.
It cannot be an alias, because it would lock the package to use either static or shared libraries at its build time. We want to decide this at the time `find_package` is called.
More recent versions of CMake emit the following warning:
CMake Deprecation Warning at cmake/CMakeLists.txt:10 (cmake_minimum_required):
Compatibility with CMake < 3.5 will be removed from a future version of
CMake.
Update the VERSION argument <min> value or use a ...<max> suffix to tell
CMake that the project does not need compatibility with older versions.
When forcing the source file language to `C`, Xcode enforces
the file to be compiled as `C` by appending `-x c` to the
compiler command line.
For now try to limit the damage and only enforce the language
if the ASM and C compilers differ.
Reproducer (CMake `3.26.4`, Xcode `14.3`):
```
cmake -S build/cmake -B _b -GXcode -DCMAKE_OSX_ARCHITECTURES=x86_64
cmake --build _b
```
Fix: #3622
