Re: [Qemu-block] [Qemu-ppc] [PATCH] qemu: include generated files with <> and not ""

[Daniel P . Berrangé]

On Wed, Mar 21, 2018 at 03:08:36PM +0200, Michael S. Tsirkin wrote:
> On Wed, Mar 21, 2018 at 08:16:00AM +0100, Thomas Huth wrote:
> > On 20.03.2018 13:05, Michael S. Tsirkin wrote:
> > > On Tue, Mar 20, 2018 at 09:58:23AM +0100, Laurent Vivier wrote:
> > >> Le 20/03/2018 à 02:54, Michael S. Tsirkin a écrit :
> > >>> QEMU coding style at the moment asks for all non-system
> > >>> include files to be used with #include "foo.h".
> > >>> However this rule actually does not make sense and
> > >>> creates issues for when the included file is generated.
> > >>
> > >> If you change that, we can have issue when a system include has the same
> > >> name as our local include. With "<FILE>", system header are taken first.
> > > 
> > > Are you sure? I just tested and that is not the case with
> > > either gcc or clang.
> > > 
> > >>> In C, include "file" means look in current directory,
> > >>> then on include search path. Current directory here
> > >>> means the source file directory.
> > >>> By comparison include <file> means look on include search path.
> > >>
> > >> Not exactly, there is the notion of "system header" too.
> > >>
> > >> https://gcc.gnu.org/onlinedocs/cpp/Include-Syntax.html
> > >>
> > >> #include <file>
> > >> This variant is used for system header files. It searches for a file
> > >> named file in a standard list of system directories. You can prepend
> > >> directories to this list with the -I option (see Invocation).
> > > 
> > > This is exactly what we do.
> > > 
> > >> #include "file"
> > >> This variant is used for header files of your own program. It searches
> > >> for a file named file first in the directory containing the current
> > >> file, then in the quote directories and then the same directories used
> > >> for <file>. You can prepend directories to the list of quote directories
> > >> with the -iquote option.
> > > 
> > > Since we do not use -iquote, "" just adds the current directory.
> > 
> > So why don't we simply switch to use -iquote instead of -I for adding
> > search paths for our own headers? We then would get a clean separation
> > of QEMU headers from system headers.
> > 
> >  Thomas
> 
> It still leaves us with a host of problems e.g. the problem of stale
> headers in the source directory.

We have a patch on list which effectively solves the problem of stale
generated files in source directory, so that's largely a non-issue at
this point IMHO.

Regards,
Daniel
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