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

[Thomas Huth <thuth@xxxxxxxxxx>]

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

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