in check_headers.cmake, we verify the self containness of a header file
by replicating it and remove `#pragma once` directive in this header.
but this approach failed to compile headers which include a header file
with the same name in the root source directory, as we add
`-I<directory-of-original-header>` in the cflags when building the
generated source file, so that it can include the headers in the same
directory. but this confuses the compiler, as, assuming we have "log.hh"
in current directory, and under the root source directory, the compiler
would always include the "log.hh" in the current directory even it
should have included "log.hh" under the root source directory.
in this change, instead of adding `-I<directory-of-original-header>` to
cflags, we just include the header under test in a new .cc file
solely generated for testing. this should address this problem.
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
Closesscylladb/scylladb#21216
6645cdf3b6