https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93545
--- Comment #3 from Arseny Solokha <asolokha at gmx dot com> --- I forgot to mention that the testcase was reduced from test/Preprocessor/has_include.c from the clang 9.0.1 test suite. Maybe gcc needs something similar in terms of completeness? There's gcc/testsuite/c-c++-common/cpp/pr88974.c already.