https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78970
--- Comment #7 from joseph at codesourcery dot com <joseph at codesourcery dot com> --- This change causes a regression testing glibc. glibc uses "gcc -E -x c-header -", which now results in an error "cannot use '-' as input filename for a precompiled header". But that use with -E is not creating a precompiled header, so should not result in an error.
