Newsgroups: comp.std.c
Path: utzoo!henry
From: henry@zoo.toronto.edu (Henry Spencer)
Subject: Re: legality of assignment of function to a void *.
Message-ID: <1990Nov13.174920.2235@zoo.toronto.edu>
Organization: U of Toronto Zoology
References: <1990Nov12.211511.2344@batcomputer.tn.cornell.edu>
Date: Tue, 13 Nov 90 17:49:20 GMT

In article <1990Nov12.211511.2344@batcomputer.tn.cornell.edu> lijewski@theory.tn.cornell.edu (Mike Lijewski) writes:
>Is a standard conforming compiler required to issue an error
>diagnostic for the following code.  Thanks.
>
>double f(double x) { return x * x; }
>   void *ptr = f;

Function pointers are a whole different universe from normal pointers, in
principle.  Free conversions to and from `void *' are allowed only for
normal pointers (see 3.3.16.1 and the cross-reference to it in 3.5.7).
Your example is not in the list of allowable combinations of operands
for `=' in 3.3.16.1's Constraints section, so you are breaking the law
and the compiler is required to diagnose it, unless I have missed some
subtlety.

Your compiler might choose to allow `void *ptr = (void *)f;', however,
as an extension.
-- 
"I don't *want* to be normal!"         | Henry Spencer at U of Toronto Zoology
"Not to worry."                        |  henry@zoo.toronto.edu   utzoo!henry