ANSI C -- static forward references

[Martin Minow]

This is one of a collection of comments on the Draft Standard, posted to
comp.lang.c for discussion before I mail a final draft to the Ansi C
committee.  Each message discusses one problem I have found with the Draft
Standard that I feel warrants a "no" vote.  Note that this message is my
personal opinion, and does not reflect on the opinions of my employer.

---- Problem:

Page 19, line 42, page 49, line 43, page 70, line 22. "static" should
be permitted only for definitions. "extern" should be the only declarator
that specifies external linkage (whether file or program).

Page 19, line 42ff.  The formulation as given here does not allow the
common use of "extern" to forward reference a variable or function that
is actually declared "static."  This breaks existing programs with sequences
such as the following:

	char *
	func()
	{
		extern char	*subr();
		...
		return (subr());
	}
	...
	static char *
	subr()
	{
		...
	}

A subsequent definition should be allowed to declare an object or function
"static," overriding the previous linkage specification.  The storage class
specifier "static" (section 3.5.1, page 49) should be permitted only on
definitions.

Page 70, line 22.  As noted above, "static" should not be used to declare
external functions with file scope.  The module referring to the function]
does not need to ``know'' that the actual function definition is in the same
file -- indeed, it should not.  If only "extern" were used to specify linkage,
the programmer would be free to move function definitions between files
as required by the application.  In the current standard, the *user* of
a function must know whether the function is defined in the current file.

The only time this use of "static" would be useful would be to permit
one-pass compilers to produce smaller code segments for function calls.
Given the current direction of the computer industry, there is no need
for such limitations.

----

Martin Minow
decvax!minow