C Compiler bug (?: operator)

[W. H. Pollock x4575 3S235]

In article <134 at sas.UUCP> jcz at sas.UUCP (Carl Zeigler) writes:
>
>  > > void f3(which)
>  > > {
>  > >     extern void f1(),f2();
>  > >     which?f1():f2();
>  > > }
>  > > cc(1) gives an "incompatible types" error.
>  > 
>  > As it should.  The only thing you're allowed to do with void values
>  > is throw them away.
>
>Scan again, Andrew, the (void) values are being thrown away.

The void values are not thrown away!  Remember that (A?B:C) is an
expression *returning a value*.  C is giving the error because it can't
determine the type of the return value.  This is clearer in the following:

	void f3(which)
	{
	    int f1();
	    void f2();
	    int foo;
	    ...
	    foo = which?f1():f2();
	    ...
	}

which results in the same error message, for the same reason.  Another
example:

	f4()
	{
	    ...
	    return ((void) expression);
	}

Note it doesn't mater what use is made of the return value (in the original
example it is thrown on the floor, which is what probably confused some
people).