Currently meson only considers what compiler/linker were used by a
Target's immediate sources or objects, not the sources of libraries it's
linked with by the link_with and link_while keywords. This means that if
given 3 libraries: libA which is C++, libB which is C, and libC which is
also C, and libC links with libB which links with libA then linking libC
will be attempted with the C linker, and will fail.
This patch corrects that by adding the compilers used by sub libraries
to the collection of compilers considered by meson when picking a
linker.
This adds a new process_compilers_late method to the BuildTarget class,
which is evaluated after process_kwargs is called. This is needed
because some D options need to be evaluated after compilers are
selected, while for C-like languages we need to check the link* targets
for language requirements, and link* targets are passed by kwargs.
This implementation is recursive, since each Target adds it's parent's
dependencies.
Currently if a target uses link_whole, and one of those archives is a
C++, but the files for the target are C linking will fail when the C
linker attempts to link the C++ files. This patches add
link_whole_targets to the list of languages in the target so the correct
linker will be selected.
Commit 325a231a added stricter keyword argument checking, but didn't enable
keyword arguments for add_projects_link_arguments() and
add_global_link_arguments(). This makes them fail with this error:
Meson encountered an error in file meson.build, line 19, column 0:
Function does not take keyword arguments.
However, the language argument is required. Removing it produces this error
instead:
Meson encountered an error in file meson.build, line 19, column 0:
Missing language definition in add_project_link_arguments
Fix this by adding 'language' as a required keyword argument. Also add calls to
these in the "146 C and CPP link" test case.