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In-Reply-To: <2692A548B75777458914AC89297DD7DA08B0866E@bronze.dolby.net>
References: <2692A548B75777458914AC89297DD7DA08B0866E@bronze.dolby.net>
Date: Wed, 18 May 2005 18:06:07 -0700 (PDT)
Subject: RE: Illegal use of reserved word in system.h
From: rdunlap@xenotime.net
To: "Gilbert, John" <JGG@dolby.com>
Cc: linux-kernel@vger.kernel.org
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Gilbert, John said:
> Hello all,
>

Hi,

FWIW, I agree with you.  I have a 'sparse' extension (that
Linus mostly wrote) that detects/warns on all C++ reserved words.

This could be part of a needed general headers cleanup,
although a fairly low priority part of it.

>
> Sorry about the automatic disclaimer at the bottom of these emails, it's
>
> part of working here at Dolby. I'm sure it doesn't apply to this
>
> discussion.
>
>
>
> I had a few responses to this bug fix request (which I did mail to this
>
> list), none were what I was hoping for, namely "This will be fixed in
>
> the next release", so allow me to clarify.
>
>
>
> The problem: Linux kernel headers use C++ reserved words as variable
>
> names. This breaks builds of C++ code that include kernel headers.
>
>
>
> Examples: The use of "new" in the macro __cmpxchg in system.h. This hits
>
> MySQL which links into the kernel headers to determine if the platform
>
> is SMP aware or not (don't ask me why.)
>
> 	The use of "virtual" in the structure drm_buf_map in drm.h, used
>
> by drm_bufs.c. This hits C++ code that uses the DRI interface to lock
>
> with vertical retrace.
>
>
>
> The solution: rename these variables, keep C++ reserved words out of
>
> headers, make this practice part of the style guide.
>
>
>
> I'm not advocating writing parts of the kernel in C++, or cleaning out
>
> reserved words in the entire kernel. I know the one and only true
>
> language is C, but for Linux to achieve world domination it needs to be
>
> inclusive at running (and building) any software in whatever language.
>
>
>
> As to the comments stating that "Userspace code shouldn't include kernel
>
> headers", that's fine in the "Hello, World", but in the real world,
>
> applications need access to devices and system resources, which means
>
> communicating with the kernel with the proper ioctls, flags, system
>
> configuration, data structures, etc., which are kept in kernel headers.
>
> For this reason, breaking these apart from the application build
>
> environment is a really bad idea, no mater what Linus Torvalds has to
>
> say about it (see
>
> http://uwsg.iu.edu/hypermail/linux/kernel/0007.3/0587.html). It needs to
>
> be an fully integrated system for everything to run correctly.
>
>
>
> Besides, I don't have time to rewrite MySQL in C to make it "correct".
>
> I've got more important things to do. ;^)
>
>
>
> So please, keep your headers clean.
>
>
>
> John Gilbert
>
> jgg@dolby.com
>
>
>
> Ignore the sig.
>
> ###############
>
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>
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-- 
~Randy
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