[Bug c++/99072] [modules] Compiling header unit with partial preprocessing (-E -fdirectives-only) twice causes CRC mismatch

[nathan at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99072

--- Comment #5 from Nathan Sidwell <nathan at gcc dot gnu.org> ---
99072_a.H:
// Empty file

99072_b.C:
export module Foo;
import "99072_a.H";

99072_c.C:
import Foo;

./cc1plus -quiet -E -fdirectives-only -fmodule-header -E 99072_a.H >
99072_a.one
./cc1plus -quiet -fpreprocessed -fdirectives-only -fmodule-header 99072_a.one
./cc1plus -quiet -fmodules-ts 99072_b.C
./cc1plus -quiet -E -fdirectives-only -fmodule-header -E 99072_a.H >
99072_a.two
./cc1plus -quiet -fpreprocessed -fdirectives-only -fmodule-header 99072_a.two
./cc1plus -quiet -fmodules-ts 99072_c.C                                      
In module imported at 99072_b.C:2:1,
of module Foo, imported at 99072_c.C:1:
./99072_a.H: error: module './99072_a.H' CRC mismatch
./99072_a.H: error: failed to read compiled module: Bad file data
./99072_a.H: note: compiled module file is 'gcm.cache/,/99072_a.H.gcm'
In module imported at 99072_c.C:1:1:
Foo: error: failed to read compiled module: Bad import dependency
Foo: note: compiled module file is 'gcm.cache/Foo.gcm'