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In article <1992Dec24.234622.29882@ll.mit.edu> tadams@ll.mit.edu ( Tony Adams) writes:
>an example of a function call which is not governed by a prototype, calling
>a (non-visible) function defined in prototype syntax.
>Would someone please report the section numbers of the standard that
>describe this programs combination of prototype and non-prototype usage.
>            float   f=1.0;
>            func(f); /* no declaration in prototype form is visible */
>    /* definition of func() is not visible  from main() */
>    func(float f) { printf("%f\n",f); }
>    c.c:11: warning: type mismatch with previous implicit declaration
>    c.c:6: warning: previous implicit declaration of `func'

ANSI Classic section 3.3.2.2, page 41 lines 28 to 32:  "If the expression
that precedes the parenthesized argument list in a function call consists
solely of an identifier, and if no declaration is visible for this identifier,
the identifier is implicitly declared exactly as if, in the innermost block
containing the function call, the declaration
    extern int identifier();
appeared."  Therefore your expression func(f) implies a declaration
    extern int func();

Your actual definition occurs later and has a parameter type list.

ANSI Classic section 3.5.4.3, page 69 lines 14 to 18:  "If one type has a
parameter type list and the other type is specified by a function declarator
that is not part of a function definition and that contains an empty
identifier list, the parameter list shall not have an ellipsis terminator
and the type of each parameter shall be compatible with the type that
results from the application of the default argument promotions."
This is in a Semantics section, so a diagnostic is not required, though it
is allowed, and any other undefined behavior is also allowed.
--
Norman Diamond       diamond@jit081.enet.dec.com
If this were the company's opinion, I wouldn't be allowed to post it.
"It's been a lovely recession."