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From: steve@taumet.com (Stephen Clamage)
Newsgroups: comp.lang.c
Subject: Re: Is this a valid ANSI program?
Message-ID: <784@taumet.com>
Date: 27 Jun 91 15:08:24 GMT
References: <609@mtndew.Tustin.CA.US> <1991Jun26.232121.29755@watmath.waterloo.edu>
Organization: Taumetric Corporation, San Diego
Lines: 27

datangua@watmath.waterloo.edu (David Tanguay) writes:

|In article <609@mtndew.Tustin.CA.US> friedl@mtndew.Tustin.CA.US (Stephen J. Friedl) writes:
|>	void foo(const char **xxx) { }
|>	main()
|>	{
|>	char	**p = 0;
|>		foo(p);
|>	}
|>
|>The compiler claims that the argument /p/ to the function foo()
|>is incompatible with the prototype, and I just don't believe it.

|I don't believe it, either. In 3.3.16.1, Simple Assignment, Constraints:
|	both operands are pointers to qualified or unqualified versions
|	of compatible types, and the type pointed to by the left has all
|	the qualifications of the type pointed to by the right

Sorry, you better believe it.  The extract from the standard you quote
explains why!  The two pointers are 'const char **xxx' and 'char **p'.
Parameter xxx points to a 'const char*', and variable p points to
a 'char *'.  These types are not compatible, so the xxx and p are not
compatible.

-- 

Steve Clamage, TauMetric Corp, steve@taumet.com