Re: [PATCH] Fix git to be (more) ANSI C99 compliant.

From: Linus Torvalds <torvalds@osdl.org>
Date: Jun 18, 2006, 16:50 UTC
Message-ID: <Pine.LNX.4.64.0606180946090.5498@g5.osdl.org>
In-Reply-To: <1150609831500-git-send-email-octo@verplant.org>

On Sun, 18 Jun 2006, Florian Forster wrote:

>
> Using this patch I was able to build git with
> $ make CFLAGS="-Wall -Werror -ansi -pedantic -std=c99 -D_XOPEN_SOURCE=500 -D_BSD_SOURCE"

"-ansi -pedantic" is really not useful.

> While most of this patch fixes void-pointer arithmetic

This one I disagree with. Doing arithmetic on "void *" is _really_ useful, and I think most compilers end up supporting it either to be compatible with gcc, or just because it's hard to not do it.

It makes code a _lot_ cleaner.

In general, explicit casts are a sign of bad programming, and "void *" is there exactly to avoid it. And doing arithmetic on pointers is useful and fairly common, and if you accept void-pointer arithmetic, it avoids a lot of ugly and useless casts.

Show 9 quoted lines

> @@ -301,9 +301,9 @@ static void fill_line_map(struct commit 
>  				if (DEBUG)
>  					printf("map: i1: %d %d %p i2: %d %d %p\n",
>  					       i1, map[i1],
> -					       i1 != -1 ? blame_lines[map[i1]] : NULL,
> +					       (void *) (i1 != -1 ? blame_lines[map[i1]] : NULL),
>  					       i2, map2[i2],
> -					       i2 != -1 ? blame_lines[map2[i2]] : NULL);
> +					       (void *) (i2 != -1 ? blame_lines[map2[i2]] : NULL));

Gaah. This is another case of casting that I'm sure is technically correct, but that I wonder whether there is any machine that actually cares..

But at least in that case I suspect the cast _may_ be required due to different pointer representations.

		Linus