All even remotely relevant GCC and Clang versions support this
attribute. The test is useful to detect support in compilers that
don't define __GNUC__ or __clang__, for example, Solaris Studio.
This matches the modified m4/ax_gcc_func_attribute.m4.
Only constructor and ifunc attribute checks were implemented.
CMake-based build doesn't have the trouble of Autoconf confdefs.h
but writing warning-free tests would still some extra care.
If looking for attribute-related warnings works well enough then
this method should be nicer than the -Werror method in CMake too.
HAVE_DECL_PROGRAM_INVOCATION_NAME is renamed to
HAVE_PROGRAM_INVOCATION_NAME. Previously,
HAVE_DECL_PROGRAM_INVOCATION_NAME was always set when
building with autotools. CMake would only set this when it was 1, and the
dos/config.h did not define it. The new macro definition is consistent
across build systems.
The syntax "if(DEFINED CACHE{FOO})" requires CMake 3.14.
In some other places the code treats the cache variables
like normal variables already (${FOO} or if(FOO) is used,
not ${CACHE{FOO}).
Thanks to ygrek for reporting the bug on IRC.
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.
Lasse Collin