Do not require dependencies for static linking when exiv2 was built as shared #2872
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Commit 63f9926 exports the dependencies for static linking to the pkg-config file. There are two problems with the implementation: - "Requires.private" in the pkg-config file makes the pkg-config implementation require the specified modules, even when not building statically - the exiv2 library build is done either shared or static, so there is no static library in case of a shared build Hence, output the dependencies for the static linking in the pkg-config file only when the exiv2 library build is not shared (i.e. static).
Commit a8c3455, commit 5e1cf4d, and commit 4dfb781 implement & add the libraries needed in case of static linking as dependencies for the cmake config file. There are two problems with the implementation: - being unconditionally there, they will make those modules required when building against exiv2, even when not building statically - the exiv2 library build is done either shared or static, so there is no static library in case of a shared build Hence, require the dependencies for the static linking in the cmake config file only when the exiv2 library build is not shared (i.e. static).
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Some distros ship both static and shared libs, how would you handle that? We still need a single .pc file that handles both. If you don't pass |
Do you have examples of this? I checked Arch, Debian (which I maintain) and thus Ubuntu, Fedora, FreeBSD, Gentoo, Mageia, OpenBSD, openSUSE, Void, and other distros are derivatives of the ones mentioned (thus sharing the build configuration). All of the ones I inspected build using the default built type, which is shared, and no static bits are shipped (with the exception of From what I can see (I also mentioned that in my commit messages), you can build only one variant at a time with cmake, and most likely the same with meson. Hence, if the situation you mention must be supported somehow, then I need to see exactly how and what for. |
No, meson has always supported building both at the same time, and it does this quite well. This is vital for cross-platform support since unix platforms frequently need this, and it works quite well there. It doesn't work quite so well on Windows (you either need to use .def files or compile every object twice, and then import libraries and static libraries both frequently use And since CMake was primarily designed to work well on Windows, it assumes the Windows model and doesn't bother to support meson -Ddefault_library=both / autotools "--enable-static --enable-shared". Distros such as Alpine and Debian often package both, when the build system supports both, but won't necessarily go out of their way to run cmake twice in order to build and install both. |
OTOH, we frequently do run CMake twice on MSYS2 and install both artifacts. |
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Very true, MSYS2 has a somewhat stronger motivation to provide both. |
exiv2 can be built either as shared library, or static, never both at the same time. Hence, requiring the dependencies needed for static linking to exiv2 when exiv2 was built shared does not make much sense, and it only adds unneeded bits to the exiv2 users.
Hence, fix both the pkg-config file, and the cmake config file, to require the dependencies needed for static linking only in case exiv2 was built as static library. This avoids e.g. having the expat and zlib development bits when using exiv2 in cmake with
find_package(exiv2).See the specific commit messages for longer descriptions.