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From: rec@elf115.uu.net (Roger Critchlow)
Newsgroups: comp.std.c
Subject: Re: Prototypes and ID lists
Summary: maybe redefined, maybe not
Message-ID: <160@elf115.uu.net>
Date: 19 Jul 89 16:02:57 GMT
References: <16803@rpp386.Dallas.TX.US> <10551@smoke.BRL.MIL>
Organization: ELF, Sea Cliff, NY
Lines: 25

In article <10551@smoke.BRL.MIL>, gwyn@smoke.BRL.MIL (Doug Gwyn) writes:
} In article <16803@rpp386.Dallas.TX.US> jfh@rpp386.Dallas.TX.US (John F. Haugh II) writes:
} -Suppose I prototype a function with
} -extern struct passwd *getpwuid (uid_t uid);
} -and later in the same compilation unit have a declaration
} -struct passwd *
} -getpwuid (uid)
} -uid_t uid;
} -{
} -	[ stuff ]
} -Is my [ supposedly ] ANSI-compliant compiler free to warn
} -me that getpwuid() has been redefined?
} 
} But it hasn't been redefined!  It's been defined just once, and
} then compatibly with the prototype declaration of its interface
} that's in scope at the point of definition.

Compatibly defined if and only if uid_t is not hiding a type which
is promoted.  If

  typedef unsigned short int uid_t;

then the function definition is not compatible with the prototype.

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