[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] qemu: include generated files with <> and not ""
On Tue, Mar 20, 2018 at 02:28:42PM +0200, Michael S. Tsirkin wrote: > On Tue, Mar 20, 2018 at 12:18:41PM +0000, Daniel P. Berrangé wrote: > > On Tue, Mar 20, 2018 at 02:12:24PM +0200, Michael S. Tsirkin wrote: > > > On Tue, Mar 20, 2018 at 09:44:06AM +0000, Daniel P. Berrangé 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. > > > > > > > > > > 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). > > > > > > > > > > #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. > > > > > > > > > > > As generated files are not in the search directory (unless the build > > > > > > directory happens to match the source directory), it does not make > > > > > > sense > > > > > > to include them with "" - doing so is merely more work for > > > > > > preprocessor > > > > > > and a source or errors if a stale file happens to exist in the > > > > > > source > > > > > > directory. > > > > > > > > > > I agree there is a problem with stale files. But linux, for instance, > > > > > asks for a "make mrproper" to avoid this. > > > > > > > > We can follow what autoconf does, and add a check to configure to see if > > > > there are generated files left in the source dir, when configuring with > > > > builddir != srcdir, and exit with error, telling user to clean their > > > > src dir first. > > > > > > > > > > This changes include directives for all generated files, across the > > > > > > tree. The idea is to avoid sending a huge amount of email. But when > > > > > > merging, the changes will be split with one commit per file, e.g. > > > > > > for > > > > > > ease of bisect in case of build failures, and to ease merging. > > > > > > > > > > > > Note that should some generated files be missed by this tree-wide > > > > > > refactoring, it isn't a big deal - this merely maintains the status > > > > > > quo, > > > > > > and this can be addressed by a separate patch on top. > > > > > > > > > > > > Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx> > > > > > > > > > > I think your idea conflicts with what Markus has started to do: > > > > > > > > Yes, I don't think we should revert what Markus started. Both ways of > > > > referencing QEMU headers have downsides, but I think "..." has fewer > > > > downsides that "<....">. > > > > > > Could you please explain what the advantage of "" is? > > > It seems to be gone since we moved headers away from > > > source. > > > > We moved *some* headers into the include/ directory tree. > > > > I still count 650+ headers which are alongside the .c files. > > So for these, we should use "". None of these are generated files though. That leads to crazy inconsistent message for developers where 50% of QEMU header files must use <> and the other 50% of header files must use "". Having a consistent message for developers is one of the key reasons why Markus submitted the patches to standardize on the use of "" for QEMU header files, leaving <> for system headers & external dependancies. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :| _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxxx https://lists.xenproject.org/mailman/listinfo/xen-devel
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