`include-what-you-use` diagnostics, in practice, are specific to
the environment's compiler and standard library. Update includes
to satisfy IWYU for our CI job under Debian 12.
Even though Makefile generators pass source files and include
directories by absolute path to the compiler, the compiler may generate
depfile paths relative to the current working directory. For example,
`ccache` with `CCACHE_BASEDIR` may transform paths this way. When
reading a depfile, convert relative dependencies to absolute paths
before placing them in `compiler_depend.make`, which is later evaluated
in the top-level build directory.
Fixes: #22364
Most calls to `MaybeConvertToRelativePath` use one of our common work
directories (e.g. top of the build tree) as the local path. Add helpers
for each of the common cases to simplify and clarify call sites.
Since one depender has multiple dependees, depend makefile generated
same depender line by line, to reduce file size and refine make file
parse speed, merge same dependers to one. And add a testcase for
large depend.make which generated source file includes 20000 header
files and run build and incremental build
Signed-off-by: Wangkai <wangkai86@huawei.com>
Signed-off-by: Zhaoyingdong <zhaoyingdong@huawei.com>
To avoid duplicate effort of depfile parsing and enhance robustness
of parsing against mal-formed depfiles in preparation of DEPFILE option
support of add_custom_command command for makefiles generators.
Each source compilation generates a dependencies file. These dependencies
files are consolidated in one file per target. This consolidation is done
as part of command 'cmake -E cmake_depends` launched before evaluation of
makefile dependency graph.
The consolidation uses the same approach as `CMake` dependencies management.
Fixes: #21321
