2008-07-29  Paul Thomas  <pault@gcc.gnu.org>

fortran/	
	* trans-expr.c (conv_parent_component_references): New function
	to build missing parent references.
	(gfc_conv_variable): Call it
	* symbol.c (gfc_add_component): Check that component name in a
	derived type extension does not appear in parent.
	(gfc_find_component): For a derived type extension, check if
	the component appears in the parent derived type by calling
	self. Separate errors for private components and private types.
	* decl.c (match_data_constant): Add extra arg to call to
	gfc_match_structure_constructor.
	(check_extended_derived_type): New function to check that a
	parent derived type exists and that it is OK for exension.
	(gfc_get_type_attr_spec): Add extra argument 'name' and return
	it if extends is specified.
	(gfc_match_derived_decl): Match derived type extension and
	build a first component of the parent derived type if OK. Add
	the f2k namespace if not present.
	* gfortran.h : Add the extension attribute.
	* module.c : Handle attribute 'extension'.
	* match.h : Modify prototypes for gfc_get_type_attr_spec and
	gfc_match_structure_constructor.
	* primary.c (build_actual_constructor): New function extracted
	from gfc_match_structure_constructor and modified to call self
	iteratively to build derived type extensions, when f2k named
	components are used.
	(gfc_match_structure_constructor): Do not throw error for too
	many components if a parent type is being handled. Use
	gfc_find_component to generate errors for non-existent or
	private components.  Iteratively call self for derived type
	extensions so that parent constructor is built.  If extension
	and components left over, throw error.
	(gfc_match_rvalue): Add extra arg to call to
	gfc_match_structure_constructor.
	* trans-array.c (gfc_conv_resolve_dependencies): If lhs and rhs
	are the same symbol, aliassing does not matter.
testsuite/
	* gfortran.dg/extends_1.f03: New test.
	* gfortran.dg/extends_2.f03: New test.
	* gfortran.dg/extends_3.f03: New test.
	* gfortran.dg/extends_4.f03: New test.
	* gfortran.dg/extends_5.f03: New test.
	* gfortran.dg/extends_6.f03: New test.
	* gfortran.dg/private_type_6.f90: Modify error message.
	* gfortran.dg/structure_constructor_7.f03: Modify error message.
	* gfortran.dg/structure_constructor_8.f03: Modify error message.

From-SVN: r138275