Revert back to a macro so that list(APPEND CMAKE_REQUIRED_DEFINITIONS)
will affect the calling scope. I had forgotten that while CMake
functions inherit the variables from the parent scope, the changes
to them are local unless using set(... PARENT_SCOPE).
This also means that the commit message in 5bb77d0920dc is wrong. The
commit itself is still fine, making it clearer that -DHAVE_SYS_PARAM_H
is only needed for specific check_c_source_compiles() calls.
Fixes: c1ea7bd0b60eed6ebcdf9a713ca69034f6f07179
Define NetBSD and Darwin/macOS feature test macros. Autoconf defines
these too (and a few others).
Define the macros on Windows except with MSVC. The _GNU_SOURCE macro
makes a difference with mingw-w64.
Use a function instead of a macro. Don't take the TARGET_OR_ALL argument
because there's always global effect because the global variable
CMAKE_REQUIRED_DEFINITIONS is modified.
Seems that the phrase "add more quotes" from sh/bash scripting
applies to CMake as well. E.g. passing an unquoted list ${FOO}
to a function that expects one argument results in only the
first element of the list being passed as an argument and
the rest get ignored. Adding quotes helps ("${FOO}").
list(INSERT ...) is weird. Inserting an empty string to an empty
variable results in empty list, but inserting it to a non-empty
variable does insert an empty element to the list.
Since INSERT requires at least one element,
"${CMAKE_THREAD_LIBS_INIT}" needs to be quoted in CMakeLists.txt.
It might result in an empty element in the list. It seems to not
matter as empty elements consistently get ignored in that variable.
In fact, calling cmake_check_push_state() and cmake_check_pop_state()
will strip the empty elements from CMAKE_REQUIRED_LIBRARIES!
In addition to quoting fixes, this fixes checks for the cache
variables in tuklib_cpucores.cmake and tuklib_physmem.cmake.
Thanks to Martin Matuška for testing and reporting the problems.
These fixes aren't tested yet but hopefully they soon will be.
This does *NOT* replace the Autotools-based build system in
the foreseeable future. See the comment in the beginning
of CMakeLists.txt.
So far this has been tested only on GNU/Linux but I commit
it anyway to make it easier for others to test. Since I
haven't played much with CMake before, it's likely that
there are things that have been done in a silly or wrong
way and need to be fixed.
