Re: [PATCH] git-compat-util: convert skip_{prefix,suffix}{,_mem} to bool

From: Jeff King <peff@peff.net>
To: "René Scharfe" <l.s.r@web.de>
Cc: git@vger.kernel.org,
	AtariDreams via GitGitGadget <gitgitgadget@gmail.com>,
	Seija Kijin <doremylover123@gmail.com>,
	Junio C Hamano <gitster@pobox.com>,
	Phillip Wood <phillip.wood@dunelm.org.uk>
Subject: Re: [PATCH] git-compat-util: convert skip_{prefix,suffix}{,_mem} to bool
Date: Thu, 21 Dec 2023 04:59:07 -0500	[thread overview]
Message-ID: <20231221095907.GC570888@coredump.intra.peff.net> (raw)
In-Reply-To: <2d30dc36-6091-4b47-846f-92d3f4a8b135@web.de>

On Sat, Dec 16, 2023 at 11:47:21AM +0100, René Scharfe wrote:

> Use the data type bool and its values true and false to document the
> binary return value of skip_prefix() and friends more explicitly.
> 
> This first use of stdbool.h, introduced with C99, is meant to check
> whether there are platforms that claim support for C99, as tested by
> 7bc341e21b (git-compat-util: add a test balloon for C99 support,
> 2021-12-01), but still lack that header for some reason.
> 
> A fallback based on a wider type, e.g. int, would have to deal with
> comparisons somehow to emulate that any non-zero value is true:
> 
>    bool b1 = 1;
>    bool b2 = 2;
>    if (b1 == b2) puts("This is true.");
> 
>    int i1 = 1;
>    int i2 = 2;
>    if (i1 == i2) puts("Not printed.");
>    #define BOOLEQ(a, b) (!(a) == !(b))
>    if (BOOLEQ(i1, i2)) puts("This is true.");
> 
> So we'd be better off using bool everywhere without a fallback, if
> possible.  That's why this patch doesn't include any.

Thanks for putting this together. I agree this is the right spot to end
up for now (and that if for whatever reason we find that some platforms
can't handle it, we probably should revert and not try the naive
fallback).

-Peff