Re: prototyping functions returning an enum, before the enum is defined

Re: prototyping functions returning an enum, before the enum is defined

[Michael Meissner]

| "Kaveh R. Ghazi" <ghazi@caip.rutgers.edu> writes:
|
| |> 	Some config/*/*.c files have extern functions returning an
| |> enum of some sort.  Eg, function_arg_padding() in sparc.c which
| |> returns an `enum direction'.  I'd like to be able to prototype these
| |> in sparc.h, but we don't have the definition of `enum direction' from
| |> expr.h yet.
| |> 
| |> 	Is it legal in both KNR and ANSI C to say:
| |>  > extern enum direction function_arg_padding();
| |> 
| |> before `enum direction' has been defined?
| |> 
| |> 	What about doing:
| |>  > enum direction;
| |>  > extern enum direction function_arg_padding();
|
| Both are wrong.  ANSI C does not have forward declarations of enum types.
| >From the C9x draft (6.5.2.3 Tags):
|
|        [#2] A type specifier of the form
|
|                enum identifier
|
|        without an enumerator list shall only appear after the  type
|        it specifies is completed.
|
| I'm pretty sure that this is unchanged from the current standard.

(the current standard is still the 1989/1990 standard).

What I've been doing is declaring the functions as taking an int instead of an
enum, and returning an int:


	#ifndef RTX_CODE
	struct rtx_def;
	#define Rtx struct rtx_def *
	#else
	#define Rtx rtx
	#endif

	#ifndef TREE_CODE
	union tree_node;
	#define Tree union tree_node *
	#else
	#define Tree tree
	#endif

	extern int foo_operand PROTO((Rtx, int));

	       /* ... */

	int
	foo_operand (op, int_mode)
	     rtx op;
	     int int_mode;
	{
	  enum machine_mode mode = (enum machine_mode)int_mode;
		/* ... */
	}

Re: prototyping functions returning an enum, before the enum is defined

[Andreas Schwab]

"Kaveh R. Ghazi" <ghazi@caip.rutgers.edu> writes:

|> 	Some config/*/*.c files have extern functions returning an
|> enum of some sort.  Eg, function_arg_padding() in sparc.c which
|> returns an `enum direction'.  I'd like to be able to prototype these
|> in sparc.h, but we don't have the definition of `enum direction' from
|> expr.h yet.
|> 
|> 	Is it legal in both KNR and ANSI C to say:
|>  > extern enum direction function_arg_padding();
|> 
|> before `enum direction' has been defined?
|> 
|> 	What about doing:
|>  > enum direction;
|>  > extern enum direction function_arg_padding();

Both are wrong.  ANSI C does not have forward declarations of enum types.
From the C9x draft (6.5.2.3 Tags):

       [#2] A type specifier of the form

               enum identifier

       without an enumerator list shall only appear after the  type
       it specifies is completed.

I'm pretty sure that this is unchanged from the current standard.

-- 
Andreas Schwab                                      "And now for something
schwab@issan.informatik.uni-dortmund.de              completely different"
schwab@gnu.org

prototyping functions returning an enum, before the enum is defined

[Kaveh R. Ghazi]

	Some config/*/*.c files have extern functions returning an
enum of some sort.  Eg, function_arg_padding() in sparc.c which
returns an `enum direction'.  I'd like to be able to prototype these
in sparc.h, but we don't have the definition of `enum direction' from
expr.h yet.

	Is it legal in both KNR and ANSI C to say:
 > extern enum direction function_arg_padding();

before `enum direction' has been defined?

	What about doing:
 > enum direction;
 > extern enum direction function_arg_padding();

	I'd like to please hear if either of these would be correct.

		Thanks,
		--Kaveh

PS: This was handled in rs6000.[ch] by making function_arg_padding()
return an int and having that int cast to an `enum direction' in the
proper place.  I'd prefer to not have to use that solution if possible.
--
Kaveh R. Ghazi			Project Manager / Custom Development
ghazi@caip.rutgers.edu		Icon CMT Corp.