Path: utzoo!utgpu!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!ukma!uflorida!haven!adm!smoke!gwyn
From: gwyn@smoke.BRL.MIL (Doug Gwyn )
Newsgroups: comp.lang.c
Subject: Re: function prototype problem
Message-ID: <8916@smoke.BRL.MIL>
Date: 18 Nov 88 02:53:19 GMT
References: <310@drd.UUCP> <1704@scolex> <8889@smoke.BRL.MIL> <1736@scolex>
Reply-To: gwyn@brl.arpa (Doug Gwyn (VLD/VMB) <gwyn>)
Distribution: na
Organization: Ballistic Research Lab (BRL), APG, MD.
Lines: 13

In article <1736@scolex> seanf@sco.COM (Sean Fagan) writes:
>So, the moral of the story:  Don't pass in char's, short's, or float's to
>your subroutines unless you want a Real(tm) ANSI C compiler to choke on it

No, that's the wrong moral.  The correct conclusion is that prototypes
for old-style-defined functions must declare the parameters with the
correctly widened types.  In other words, when converting to prototypes
either convert EVERY reference to a function AND its definition to use
compatible prototypes (in which case any appropriate argument type can be
declared), or else use only widened parameter types.  For example,
	extern double sin(float);
is wrong because for reasons of compatibility the parameter must be
of type double by the time it reaches the innards of the function.