Path: utzoo!attcan!uunet!samsung!rex!ames!amdcad!nucleus!tim
From: tim@nucleus.amd.com (Tim Olson)
Newsgroups: comp.os.minix
Subject: Re: float VS double: The return...
Message-ID: <29828@amdcad.AMD.COM>
Date: 11 Apr 90 14:30:54 GMT
References: <16383@nigel.udel.EDU> <29812@amdcad.AMD.COM> <460@helios.prosys.se>
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Reply-To: tim@amd.com (Tim Olson)
Organization: Advanced Micro Devices, Inc., Austin, Texas
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In article <460@helios.prosys.se> ath@prosys.se (Anders Thulin) writes:
| No. The ANSI C standard also tries very hard not to introduce backward
| incompabilities.  The example above works just the way K&R says:
| c becomes an int, and f a double by widening, provided there isn't
| a new-style definition of f lurking in some corner.
| 
| In the presence of a new-style definition, like
| 
| 	f(char c, float f);
| 
| c would indeed be a char and f a float. 
| 
| I can't quote the ANSI gospel, but K&R, 2nd ed, Section A7.3.2 Function
| calls, p.201-202 provides more info.

This section really only discusses promotion of arguments by the
caller, which should be done.  However, I was referring to
X3J11/88-159 (December 7 draft, just before ratification), which
explicitly states (as a noted QUIET CHANGE) that the received, widened
argument must be narrowed upon entry, and that type rewriting is not
allowed.

I checked it with two ANSI-conforming compiler we have here (MetaWare
HighC and gcc with -ansi -pedantic flags), and they both agree with
this.


	-- Tim Olson
	Advanced Micro Devices
	(tim@amd.com)