[Bug preprocessor/55115] [>=4.5.0 regression] missing headers as fatal breaks cproto logic

["redi at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55115

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> 2012-10-29 14:29:44 UTC ---
(In reply to comment #1)
> If the headers do nothing, just delete them? If the headers do something, how
> can you preprocess the file without the info from the headers?

That won't work, I believe cproto parses the errors produced by GCC and figures
out which declarations are missing based on the errors, then creates a header
containing those declarations.

Adding an option just for cproto is definitely not a good idea, just fix cproto
instead.  The right answer seems to be to create a directory of empty files
with the names of the missing headers and point GCC to it with -I then cproto
can proceed as normal, and generate replacements for the empty files.

Refusing to compile when a header is missing is a huge improvement on the old
behaviour.