[Patch, fortran] Parameterized Derived Types

[Paul Richard Thomas <paul dot richard dot thomas at gmail dot com>]

Dear All,

Since my message to the list of 16 August 2017 I have put in another
intense period of activity to develop a patch to implement PDTs in
gfortran. I have now temporarily run out of time to develop it
further; partly because of a backlog of other patches and PRs to deal
with but also pressure from daytime work.

The patch adds the last unimplemented F2003 feature to gfortran.

As in the provisional patch, I have attached some notes on the
implementation. This indicates some of the weaknesses, problem areas
and TODOs.

Suggest that a good read of Mark Leair's excellent PGInsider article
on PDTs -  http://www.pgroup.com/lit/articles/insider/v5n2a4.htm is a
worthwhile exercise.

To judge by the complete silence following my previous message, I will
have a problem getting this patch reviewed. I would welcome any
remarks or reviews but intend to commit, warts and all, on Saturday
unless something fundamentally wrong comes out of the woodwork.

Note that the PDT parts in the compiler are rather well insulated from
the rest of fortran and that I do not believe that any regressions
will result.

I hope that a month or two of testing in other hands will add to the
list of TODOs and that when I return to PDTs a greatly improved
version will result.

Bootstrapped and regtested on FC23/x86_4 - OK for trunk? (Note above
remark about committing on Saturday in the absence of a review.)

Best regards

Paul

2017-09-05  Paul Thomas  <pault@gcc.gnu.org>

    * decl.c : Add decl_type_param_list, type_param_spec_list as
    static variables to hold PDT spec lists.
    (build_sym): Copy 'type_param_spec_list' to symbol spec_list.
    (build_struct): Copy the 'saved_kind_expr' to the component
    'kind_expr'. Check that KIND or LEN components appear in the
    decl_type_param_list. These should appear as symbols in the
    f2k_derived namespace. If the component is itself a PDT type,
    copy the decl_type_param_list to the component param_list.
    (gfc_match_kind_spec): If the KIND expression is parameterized
    set KIND to zero and store the expression in 'saved_kind_expr'.
    (insert_parameter_exprs): New function.
    (gfc_insert_kind_parameter_exprs): New function.
    (gfc_insert_parameter_exprs): New function.
    (gfc_get_pdt_instance): New function.
    (gfc_match_decl_type_spec): Match the decl_type_spec_list if it
    is present. If it is, call 'gfc_get_pdt_instance' to obtain the
    specific instance of the PDT.
    (match_attr_spec): Match KIND and LEN attributes. Check for the
    standard and for type/kind of the parameter. They are also not
    allowed outside a derived type definition.
    (gfc_match_data_decl): Null the decl_type_param_list and the
    type_param_spec_list on entry and free them on exit.
    (gfc_match_formal_arglist): If 'typeparam' is true, add the
    formal symbol to the f2k_derived namespace.
    (gfc_match_derived_decl): Register the decl_type_param_list
    if this is a PDT. If this is a type extension, gather up all
    the type parameters and put them in the right order.
    *dump-parse-tree.c (show_attr): Signal PDT templates and the
    parameter attributes.
    (show_components): Output parameter atrributes and component
    parameter list.
    (show_symbol): Show variable parameter lists.
    * expr.c (expr.c): Copy the expression parameter list.
    (gfc_is_constant_expr): Pass on symbols representing PDT
    parameters.
    (gfc_check_init_expr): Break on PDT KIND parameters and
    PDT parameter expressions.
    (gfc_check_assign): Assigning to KIND or LEN components is an
    error.
    (derived_parameter_expr): New function.
    (gfc_derived_parameter_expr): New function.
    (gfc_spec_list_type): New function.
    * gfortran.h : Add enum gfc_param_spec_type. Add the PDT attrs
    to the structure symbol_attr. Add the 'kind_expr' and
    'param_list' field to the gfc_component structure. Comment on
    the reuse of the gfc_actual_arglist structure as storage for
    type parameter spec lists. Add the new field 'spec_type' to
    this structure. Add 'param_list' fields to gfc_symbol and
    gfc_expr. Add prototypes for gfc_insert_kind_parameter_exprs,
    gfc_insert_parameter_exprs, gfc_add_kind, gfc_add_len,
    gfc_derived_parameter_expr and gfc_spec_list_type.
    * interface.c (gfc_compare_derived_types): Treat PDTs in the
    same way as sequence types.
    * match.c : Add variable 'type_param_spec_list'.
    (gfc_op2string, gfc_match_member_sep, gfc_match_label): Remove
    trailing whitespace.
    (match_derived_type_spec): Match PDTs and find specific
    instance.
    (gfc_match_type_spec): Remove more trailing whitespace.
    (gfc_match_allocate): Assumed or deferred parameters cannot
    appear here. Copy the type parameter spec list to the expr for
    the allocatable entity. Free 'type_param_spec_list'.
    (gfc_match_common, gfc_match_namelist, gfc_match_module): Still
    more trailing whitespace to remove.
    (gfc_match_type_is): Allow PDT typespecs.
    * match.h : Modify prototypes for gfc_match_formal_arglist and
    gfc_match_actual_arglist.
    * module.c (ab_attribute, mstring attr_bits): PDT attributes
    added.
    (mio_symbol_attribute): PDT attributes handled.
    (mio_component): Deal with 'kind_expr' field.
    (mio_full_f2k_derived): For PDT templates, transfer the formal
    namespace symroot to the f2k_derived namespace.
    *primary.c (match_keyword_arg, gfc_match_actual_arglist): Add
    modifications to handle PDT spec lists. These are flagged in
    both cases by new boolean arguments, whose prototype defaults
    are false.
    (gfc_match_structure_constructor, match_variable): Remove yet
    more trailing whitespace.
    * resolve.c (get_pdt_spec_expr, get_pdt_constructor): New
    functions.
    (resolve_structure_cons): If the constructor is a PDT template,
    call get_pdt_constructor to build it using the parameter lists
    and then get the specific instance of the PDT.
    (resolve_component): PDT strings need a hidden string length
    component like deferred characters.
    (resolve_symbol): Dummy PDTs cannot have deferred parameters.
    * symbol.c (gfc_add_kind, gfc_add_len): New functions.
    (free_components): Free 'kind_expr' and 'param_list' fields.
    (gfc_free_symbol): Free the 'param_list' field.
    (gfc_find_sym_tree): If the current state is a PDT template,
    look for the symtree in the f2k_derived namspaces.
    trans-array.c (structure_alloc_comps): Allocate and deallocate
    PDTs. Check dummy arguments for compliance of LEN parameters.
    Add the new functions to the preceeding enum.
    (gfc_allocate_pdt_comp, gfc_deallocate_pdt_comp and
    gfc_check_pdt_dummy): New functions calling above.
    * trans-array.h : Add prototypes for these functions.
    trans-decl.c (gfc_get_symbol_decl): Call gfc_defer_symbol_init
    as appropriate for PDT symbols.
    (gfc_trans_deferred_vars): Allocate/deallocate PDT entities as
    they come into and out of scope. Exclude pdt_types from being
    'gcc_unreachable'.
    (gfc_trans_subcomponent_assign): PDT array components must be
    handles as if they are allocatable.
    * trans-stmt.c (gfc_trans_allocate): Handle initialization of
    PDT entities.
    (gfc_trans_deallocate): Likewise.
    * trans-types.c (gfc_get_derived_type): PDT templates must not
    arrive here. PDT string components are handles as if deferred.
    Similarly, PDT arrays are treated as if allocatable. PDT
    strings are pointer types.
    * trans.c (gfc_deferred_strlen): Handle PDT strings in the same
    way as deferred characters.


2017-09-05  Paul Thomas  <pault@gcc.gnu.org>

    * gfortran.dg/pdt_1.f03 : New test.
    * gfortran.dg/pdt_2.f03 : New test.
    * gfortran.dg/pdt_3.f03 : New test.
    * gfortran.dg/pdt_4.f03 : New test.
    * gfortran.dg/pdt_5.f03 : New test.

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