From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.org/gmane.linux.lib.musl.general/7400 Path: news.gmane.org!not-for-mail From: Rich Felker Newsgroups: gmane.linux.lib.musl.general Subject: Re: Explicit casts in ctype.h suppress compiler warnings Date: Fri, 17 Apr 2015 12:50:49 -0400 Message-ID: <20150417165049.GZ6817@brightrain.aerifal.cx> References: Reply-To: musl@lists.openwall.com NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Trace: ger.gmane.org 1429289470 27986 80.91.229.3 (17 Apr 2015 16:51:10 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Fri, 17 Apr 2015 16:51:10 +0000 (UTC) To: musl@lists.openwall.com Original-X-From: musl-return-7413-gllmg-musl=m.gmane.org@lists.openwall.com Fri Apr 17 18:51:05 2015 Return-path: Envelope-to: gllmg-musl@m.gmane.org Original-Received: from mother.openwall.net ([195.42.179.200]) by plane.gmane.org with smtp (Exim 4.69) (envelope-from ) id 1Yj9Tr-0007OE-Tx for gllmg-musl@m.gmane.org; Fri, 17 Apr 2015 18:51:04 +0200 Original-Received: (qmail 5423 invoked by uid 550); 17 Apr 2015 16:51:02 -0000 Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: Original-Received: (qmail 5402 invoked from network); 17 Apr 2015 16:51:01 -0000 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Original-Sender: Rich Felker Xref: news.gmane.org gmane.linux.lib.musl.general:7400 Archived-At: On Fri, Apr 17, 2015 at 01:59:14PM +0300, Alexander Monakov wrote: > For the following erroneous source code: > > #include > int f(char *c) > { > return isdigit(c) || isspace(c); > } > > GCC warns only for passing a pointer to isspace; isdigit is implemented as a > macro that casts its argument to unsigned, and the warning is suppresed > because the origin of the cast is in a system header. Since isspace is > implemented with a static inline helper function, there is a warning. With > glibc headers, no warning is issued in either case for a similar reason. > > I think it would be nice if musl's ctype.h could aid the compiler in > diagnosing erroneous use, like it happens today for only for isspace() of all > macros declared there. The cost of restructuring the header to achieve that > does not seem too high. Thoughts? Do you have an idea in mind for how we could achieve that? I suspect the macros are still better optimizable than the inline function approach, so I'd lean towards doing a macro that avoids evaluating c and just checks its type, which would involve using ?: I think. Rich