https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98591
Bug ID: 98591
Summary: [11 Regression] -x c++-header -fsyntax-only fails:
cc1plus: error: output filename specified twice
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: driver
Assignee: unassigned at gcc dot gnu.org
Reporter: slyfox at gcc dot gnu.org
Target Milestone: ---
The bug is originally observed by andy on keyutils-1.6.3 at
https://bugs.gentoo.org/764371. There build system checks own headers for valid
syntax.
The minimal reproducer is (original uses real .h header file, possibly to make
sure C header is parsed correctly as valid C++):
```shell
$ g++-10.2.0 -x c++-header -fsyntax-only /dev/null
<ok>
$ g++-11.0.0 -x c++-header -fsyntax-only /dev/null
cc1plus: error: output filename specified twice
```
