Parsing deferred type parameter

[Steve Kargl]

Here's a patch that does the parsing and some
error checking of deferred type parameter.
It is accomplished by adding a bool to gfc_typespec
to note when a deferred type parameter is encountered.
Currently, the patch does

1) Checks that a deferred type parameter does not appear
   in an array constructor, ie,
   s = [character(len=:) :: 'ab', 'cd']  ! Invalid.

2) Checks that a deferred type parameter does not appear
   in an allocate statement, ie,
   allocate(character(len=:) :: s)  ! Invalid.

3) Checks that a variable declared with a deferred type
   parameter has either the pointer or allocatable attribute.

4) Checks that a variable with a deferred type parameter
   does not appear in a specification or initialization 
   expression, ie,
   character(len=:), allocatable :: s
   integer, parameter :: n = len(s)

5) Prevents errors about assumed shaped arrays and assumed
   length characters when a deferred type parameter is 
   encountered.

For now, if a variable with a deferred type parameter is
used in a program gfortran issues an error that this 
feature is not implemented.

Two items are left:

1) Check for any restrictions with actual and dummy arguments.

2) Write the code for trans-* to actually make this feature
   work.  I suspect that I can use some help from others here;
   otherwise, it may take months (years?) to finish this up.

I have only written some limted tests, so I suspect that there
may be issues with things like components of derived types that
use deferred type parameters and function results.  

Anyway, to keep this patch from getting lost again in a dusty
corner of my hard drive, I thought I would post it here.

-- 
Steve
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2010-08-15  Steven G. Kargl  <kargl@gcc.gnu.org>

	* gfortran.dg/initialization_9.f90: Update error message.
	* gfortran.dg/allocate_derived_1.f90: Ditto.
	* gfortran.dg/initialization_1.f90: Ditto.

2010-08-15  Steven G. Kargl  <kargl@gcc.gnu.org>

	* fortran/decl.c (char_len_param_value) Pass a second argument
	for parsing a deferred type parameter.
	(match_char_length, gfc_match_char_spec): Use it.
	* fortran/array.c (gfc_match_array_constructor): type-spec in
	an array constructor cannot have a deferred type parameter.
 	* fortran/gfortran.h: Add a bool 'deferred' component to the
	gfc_typespec structure.  Fix a typo in a comment.
	* fortran/expr.c (check_inquiry):  A deferred type parameter variable
	cannot appear in len() within a specification or initialization 
	expression.
	* fortran/resolve.c (resolve_charlen):  Add a FIXME above the function
	as a reminder to recheck this function.
	(resolve_fl_var_and_proc): Prevent an error message about a deferred
	shape array when the variable has a deferred type parameter.
	(resolve_fl_variable): Check that a variable with a deferred type
	parameter has the pointer or allocatable attribute.  Prevent an
	error about an assumed character length when a deferred length
	variable is encountered.
	* fortran/trans-decl.c (gfc_trans_deferred_vars): Issue a
	fatal error when translating a deferred type parameter.
	* fortran/match.c (match_type_spec): Remove part of the derive
	type checking, which causes problems for intrinsic type-specs in
	an allocate statement.  Replace 'goto char_selector' with the
	4 lines of code to avoid an unnecessary jump.
	(gfc_match_allocate): Add  deferred_locus and saw_deferred do allow
	error checking of deferred type parameter allocate-objects.  A
	type-spec in an allocate statement cannot have a deferred type 
	parameter.  For an allocate-object with a deferred type parameter
	issue an error until full support is available.  Check constraint
	F2003:C623.
	* fortran/misc.c (gfc_clear_ts): Set ts.deferred to false.
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