Pointers to Incomplete Types in Prototypes

[Joseph Schwartz]

Must an ANSI C compiler accept pointers to incomplete types in a
function prototype?
 
More specifically, if struct bar has not been defined, is an ANSI
compiler allowed to reject the following prototype:
 
    extern void foo(struct bar *);

According to 3.1.2.5, struct bar is an incomplete type in this case,
and struct bar * is a pointer to an incomplete type.
 
I couldn't find anything in 3.5.4.3 that allows or forbids incomplete
types, or pointers to them, in function prototypes.  Can anyone give
me more conclusive information?  Our HP "ANSI" C compiler is complaining
about the above prototype, and I want some ammunition before I report
it to HP as a problem.
 
Thanks in advance for any help you can provide.


-- 
Joe Schwartz
Internet: xor at mts.rpi.edu
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