Re: [PATCH] hurd: Add shared mig declarations

[Samuel Thibault <samuel.thibault@gnu.org>]

Simon Marchi, le sam. 30 mai 2020 21:51:35 -0400, a ecrit:
> On 2020-05-30 2:23 p.m., Samuel Thibault wrote:
> > Fixes
> > 
> > exc_request_S.c:177:24: error: no previous declaration for ‘exc_server’ [-Werror=missing-declarations]
> >   177 | mig_external boolean_t exc_server
> > 
> > gdb/ChangeLog:
> > 
> > 	* config/i386/i386gnu.mn [%_S.o %_U.o] (COMPILE.post): Add
> > 	"-include gnu-nat-mig.h".
> > 	* gnu-nat-mig.h: New file.
> > 	* gnu-nat.c: Include "gnu-nat-mig.h".
> > 	(exc_server, msg_reply_server, notify_server,
> > 	process_reply_server): Remove declarations.
> 
> It took me a while to understand the underlying problem.  My understanding is that
> gnu-nat.c calls this function exc_server, that is defined in the generated file.  The
> generated file does not provide a header with declarations, so gnu-nat.c had its own
> local declaration.  Since we now use the -Wmissing-declarations warning flag, and the
> definition in the generated exc_request_S.c didn't see a corresponding declaration,
> it caused that build failure.  Is that correct?  If so, please add that explanation
> or equivalent to the commit log.

I have now added

“
We are using -Werror=missing-declarations, and the _S.h files generated
by mig do not currently include a declaration for the server routine.
gnu-nat.c used to have its own external declarations, but better just
share them between gnu-nat.c and the _S.c files.
”

> My question now is: that MIG tool appears to generate both a header (%_S.h) and source
> file (%_S.c) from defs files.  What is this header file used for, if it doesn't contain
> the declaration for the functions in the source file?

Mig does include declarations for the functions of the .c files, but
not for the server routine, I don't know why that was never implemented
there (this hasn't been touched since the VCS initial import).

Samuel