Re: [9fans] function inconsistently declared

Re: [9fans] function inconsistently declared

[rog]

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don't mix ANSI and non-ANSI function declarations and definitions!

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From: "Zoltan Jarai" <jarai@mail.tvnet.hu>
To: 9fans@cse.psu.edu
Subject: [9fans] function inconsistently declared
Date: Tue, 1 Oct 2002 18:23:26 +0200
Message-ID: <9b9bee4f2f9cf8257bfa185a67d8f8d5@mail.tvnet.hu>

I suspect this must be elementary but could someone, please, enlighten
me why the code fragment below produces an error message:

cpu% 8c -FVw c.c
c.c:4 function inconsistently declared: f
cpu% cat c.c
int f(int,char);
int f(a,b)
	int a;
	char b;
{
  return a+b;
}
cpu%

Re: [9fans] function inconsistently declared

[Douglas A. Gwyn]

C H Forsyth wrote:
> in old C,
>         f(a, b)
>         int a;
>         char b;
>         {
>         ...
>         }
> actual parameters for b were always promoted to int
> (since prototypes weren't available, and the compiler didn't maintain a
> file of the types of parameters to internal and external functions, it
> had to assume int for char, double for float etc.)

Actually it didn't *have* to, but it was convenient for the way
PDP-11 function linkage worked.

In the presence of a prototype, it is quite possible for the
compiler to use a linkage that differs from the one used for
unprototyped functions.  In this regard also remember that
use of a variable-argument function requires that the ,...)
prototype be visible; quite a few systems use a linkage for
that situation that is different from the one for unprototyped
functions.  I still occasionally have to fix up some legacy
code like:
	error("foo %d\n",1);	/* no prototype in scope */
	error("punt\n");
	...
	void error(char *fmt, int x) {
		... something involving &x
	}

Re: [9fans] function inconsistently declared

[C H Forsyth]

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in old C,
	f(a, b)
	int a;
	char b;
	{
	...
	}
actual parameters for b were always promoted to int
(since prototypes weren't available, and the compiler didn't maintain a
file of the types of parameters to internal and external functions, it
had to assume int for char, double for float etc.)

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From: "Zoltan Jarai" <jarai@mail.tvnet.hu>
To: 9fans@cse.psu.edu
Subject: Re: [9fans] function inconsistently declared
Date: Tue, 1 Oct 2002 18:51:29 +0200
Message-ID: <3240710031bd9277e11a3841ab24d68c@mail.tvnet.hu>

Thanks for the quick replies!  What was really baking my noodle was
that if all arguments are int's the function compiles.  So I guess the
compiler just ignores pre-ANSI declaration and assumes int.

Thanks,
Zoli

Re: [9fans] function inconsistently declared

[Zoltan Jarai]

Thanks for the quick replies!  What was really baking my noodle was
that if all arguments are int's the function compiles.  So I guess the
compiler just ignores pre-ANSI declaration and assumes int.

Thanks,
Zoli

Re: [9fans] function inconsistently declared

[Russ Cox]

the compiler treats mixing
ansi prototypes and pre-ansi function
declarations as an inconsistent declaration.

russ

[9fans] function inconsistently declared

[Zoltan Jarai]

I suspect this must be elementary but could someone, please, enlighten
me why the code fragment below produces an error message:

cpu% 8c -FVw c.c
c.c:4 function inconsistently declared: f
cpu% cat c.c
int f(int,char);
int f(a,b)
	int a;
	char b;
{
  return a+b;
}
cpu%