Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!mcnc!uvaarpa!haven!adm!smoke!gwyn
From: gwyn@smoke.brl.mil (Doug Gwyn)
Newsgroups: comp.lang.c
Subject: Re: Behavior of #error preprocessor directive
Keywords: preprocessor directives ANSI standard
Message-ID: <14792@smoke.brl.mil>
Date: 9 Jan 91 08:37:01 GMT
References: <1192@van-bc.wimsey.bc.ca>
Organization: U.S. Army Ballistic Research Laboratory, APG, MD.
Lines: 19

In article <1192@van-bc.wimsey.bc.ca> jtc@van-bc.wimsey.bc.ca (J.T. Conklin) writes:
>Is use of the #error preprocessor directive required (or permitted) to
>halt compilation of a source module.

#error produces a diagnostic message, nothing more.

>In any case, was anything like my #warning directive discussed during
>the standardization process?

Yes.  We spelled it #error, though.

Note that code intended to be compiled (with appropriate conditionalizing)
by both ANSI and pre-ANSI compilers should not use #error, because many
pre-ANSI C preprocessors would terminate fatally upon seeing #error, even
in #ifed-out source code.  Thus I tend to still use the kludge
	#if SOME_EXPR
	#include "*** ERROR -- SOME_EXPR ***"
	#endif
which has a more drastic effect than #error anyway.