cmake documentation is absolutely atrocious, and I don't know why they
mention all the wrong things to use, and the cargo cult of successfully
writing a cmake build definition (copy-pasting what works from other
projects) also uses all the wrong things. But it turns out it is
possible to correctly link a PkgConfig target despite all that, at
least, *iff* you use cmake >= 3.13. I've chosen option 2, which is to
vendor in cmake >= 3.13's FindPkgConfig module in the previous commit.
Using IMPORTED_TARGET GLOBAL in a pkg-config check will result in a
proper linker target being created. For comparison, this is like using
meson's dependency() target, except meson forces you to do this by
default. The result is that the build system's internal representation
of how to link something, is used instead of manually passing build
flags defined in variables.
This is an important distinction to make, because cmake does not have a
list datatype, and instead turns lists into strings separated by ';'
which are indistinguishable from, like, strings which contain ';'
characters. When you pass the resulting list-which-isn't-really-a-list
to link an executable/library, you either need to preprocess the
variable to replace ';' with ' ' (just in case there are multiple
elements) or use cmake functions which magically know to do this
themselves -- or at least, I assume there are cmake functions that
correctly handle so-called "lists", or there would be no need for
"lists" to exist.
The IMPORTED_TARGET will define a bunch of INTERFACE_* properties which
do seem to do exactly this. The resulting build definition should
actually, correctly, link python, thereby fixing #1398 in a better way.
fixes incorrect (non)detection of libpython3.Ym.so due to PEP 3149 since
python's officially exported build flags know how to correctly link to
python.
Allows for custom LIBDIR to specified with cmake builds. WEECHAT_LIBDIR
is used for a custom Weechat directory, or set from LIBDIR (as LIBDIR
used to be set).
Sébastien Helleu