Studying note of GCC-3.4.6 source (113)

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5.12.3.2.1.2.2. Close the class definition

Returns from expand_or_defer_fn à cp_parser_late_parsing_for_memberà cp_parser_late_parsing_for_member à cp_parser_class_specifierà cp_parser_type_specifier à cp_parser_decl_specifier_seqà cp_parser_single_declaration, following codewill be executed.

cp_parser_single_declaration (continue)

14549 /*Check for the declaration of a template class. */

14550 if (declares_class_or_enum)

14551 {

14552 if (cp_parser_declares_only_class_p(parser))

14553 {

14554 decl = shadow_tag (decl_specifiers);

14555 if (decl)

14556 decl = TYPE_NAME(decl);

14557 else

14558 decl = error_mark_node;

14559 }

14560 }

14561 /*If it's not a template class, try for a template function. If

14562 thenext token is a `;', then this declaration does not declare

14563 anything. But, if there were errors in the decl-specifiers, then

14564 theerror might well have come from an attempted class-specifier.

14565 Inthat case, there's no need to warn about a missing declarator. */

14566 if (!decl

14567 &&(cp_lexer_next_token_is_not (parser->lexer, CPP_SEMICOLON)

14568 || !value_member(error_mark_node, decl_specifiers)))

14569 decl = cp_parser_init_declarator (parser,

14570 decl_specifiers,

14571 attributes,

14572 /*function_definition_allowed_p=*/true,

14573 member_p,

14574 declares_class_or_enum,

14575 &function_definition_p);

14576

14577 pop_deferring_access_checks ();

14578

14579 /*Clear any current qualification; whatever comes next is the start

14580 ofsomething new. */

14581 parser->scope =NULL_TREE;

14582 parser->qualifying_scope= NULL_TREE;

14583 parser->object_scope =NULL_TREE;

14584 /*Look for a trailing `;' after the declaration. */

14585 if (!function_definition_p

14586 && (decl ==error_mark_node

14587 ||!cp_parser_require (parser, CPP_SEMICOLON, "`;'")))

14588 cp_parser_skip_to_end_of_block_or_statement (parser);

14589

14590 returndecl;

14591 }

As we have seen, declares_class_or_enum is set to the bitwise orof the following flags:

1: one of the decl-specifiers is an elaborated-type-specifier (i.e.,a type declaration)

2: one of the decl-specifiers is an enum-specifier or aclass-specifier (i.e., a type definition)

So if declares_class_or_enumis non-zero, it needs further to see if it is the class definition. If so, somesainty check should be taken just like those executed for nested class informer section.

As now only finish decl-specifier-seq part in “decl-specifier-seq[opt]init-declarator [opt];”, cp_parser_declares_only_class_p is used to seeif declarator exists.

15029 static bool

15030 cp_parser_declares_only_class_p (cp_parser *parser) in parser.c

15031 {

15032 /*If the next token is a `;' or a `,' then there is no

15033 declarator. */

15034 return(cp_lexer_next_token_is (parser->lexer, CPP_SEMICOLON)

15035 || cp_lexer_next_token_is (parser->lexer,CPP_COMMA));

15036 }

If there is not delcarator, it should be type declaration whichshould be verified.

3608 tree

3609 shadow_tag (tree declspecs) in decl.c

3610 {

3611 tree t = check_tag_decl (declspecs);

3612

3613 if (!t)

3614 returnNULL_TREE;

3615

3616 maybe_process_partial_specialization (t);

3617

3618 /*This is where the variables in an anonymous union are

3619 declared. An anonymous union declaration looks like:

3620 union{ ... } ;

3621 because there is no declarator after the union, the parser

3622 sendsthat declaration here. */

3623 if (ANON_AGGR_TYPE_P (t))

3624 {

3625 fixup_anonymous_aggr (t);

3626

3627 if (TYPE_FIELDS (t))

3628 {

3629 tree decl =grokdeclarator (NULL_TREE, declspecs, NORMAL,0,

3630 NULL);

3631 finish_anon_union(decl);

3632 }

3633 }

3634

3635 returnt;

3636 }

Above check_tag_decl returns the type declared (nodeof *_TYPE) or NULL if none, which in turn is returned by shadow_tag. Then in cp_parser_single_declaration,at line 14556, decl points to the TYPE_DECL node. At line 14566, decl if NULL, meansit’s not a type declaration, as cp_parser_single_declaration is only invokedby cp_parser_explicit_specializationor cp_parser_template_declaration_after_export(here is the rear), the left possibility is of function template, which isparsed by cp_parser_init_declaratorat line 14569.

From cp_parser_single_declaration back to cp_parser_template_declaration_after_export.

cp_parser_template_declaration_after_export(continue)

14461 else

14462 {

14463 decl = cp_parser_single_declaration (parser,

14464 member_p,

14465 &friend_p);

14466

14467 /*If this is a member template declaration, let the front

14468 endknow. */

14469 if (member_p &&!friend_p && decl)

14470 {

14471 if (TREE_CODE (decl) ==TYPE_DECL)

14472 cp_parser_check_access_in_redeclaration (decl);

14473

14474 decl =finish_member_template_decl (decl);

14475 }

14476 else if (friend_p&& decl && TREE_CODE (decl) == TYPE_DECL)

14477 make_friend_class (current_class_type,TREE_TYPE (decl),

14478 /*complain=*/true);

14479 }

14480 /*We are done with the current parameter list. */

14481 --parser->num_template_parameter_lists;

14482

14483 /*Finish up. */

14484 finish_template_decl (parameter_list);

14485

14486 /*Register member declarations. */

14487 if (member_p &&!friend_p && decl && !DECL_CLASS_TEMPLATE_P (decl))

14488 finish_member_declaration(decl);

14489

14490 /*If DECL is a function template, we must return to parse it later.

14491 (Eventhough there is no definition, there might be default

14492 arguments that need handling.) */

14493 if (member_p && decl

14494 && (TREE_CODE(decl) == FUNCTION_DECL

14495 ||DECL_FUNCTION_TEMPLATE_P (decl)))

14496 TREE_VALUE(parser->unparsed_functions_queues)

14497 = tree_cons(NULL_TREE, decl,

14498 TREE_VALUE (parser->unparsed_functions_queues));

14499 }

Above, for our example template declaration, it is not a member, soargument member_pis false. Then for the example, the only operation is done by finish_template_decl.

2208 void

2209 finish_template_decl (tree parms) insemantics.c

2210 {

2211 if (parms)

2212 end_template_decl ();

2213 else

2214 end_specialization ();

2215 }

Argument parms is extracted within “<>”, so if it isNULL, it must be a specialization.

2279 void

2280 end_template_decl (void) inpt.c

2281 {

2282 reset_specialization ();

2283

2284 if (!processing_template_decl)

2285 return;

2286

2287 /*This matches the pushlevel in begin_template_parm_list. */

2288 finish_scope();

2289

2290 --processing_template_decl;

2291 current_template_parms = TREE_CHAIN(current_template_parms);

2292 }

At finishing template declaration, it means we arriving at the edgeof its scope. The scope is closed by finish_scope too. And remember to decreasethe number of template declaration under processing. Refers to figurelayout of nested template parameters, above at line 2291, field TREE_CHAINof current_template_parmsrefers to the template argument of the containing template if it exits.

354 void

355 finish_scope (void) in decl.c

356 {

357 poplevel (0, 0, 0);

358 }

For convience, we present the code of poplevel in below again. Aswe are exiting from class scope, so argument functionbody is 0; and keep is0 then no BLOCK node will be created for the declarations within the scope.

423 tree

424 poplevel (int keep, int reverse, int functionbody) indecl.c

425 {

426 tree link;

427 /*The chain of decls was accumulated in reverse order.

428 Put itinto forward order, just for cleanliness. */

429 tree decls;

430 int tmp = functionbody;

431 int real_functionbody;

432 tree subblocks;

433 tree block = NULL_TREE;

434 tree decl;

435 int leaving_for_scope;

436 scope_kind kind;

…

454 if (current_binding_level->keep)

455 keep = 1;

…

493 /*Get the decls in the order they were written.

494 Usually current_binding_level->names is in reverse order.

495 Butparameter decls were previously put in forward order. */

496

497 if (reverse)

498 current_binding_level->names

499 = decls = nreverse(current_binding_level->names);

500 else

501 decls =current_binding_level->names;

502

503 /*Output any nested inline functions within this block

504 ifthey weren't already output. */

505 for(decl = decls; decl; decl = TREE_CHAIN (decl))

506 if (TREE_CODE (decl) ==FUNCTION_DECL

507 && !TREE_ASM_WRITTEN (decl)

508 && DECL_INITIAL(decl) != NULL_TREE

509 &&TREE_ADDRESSABLE (decl)

510 &&decl_function_context (decl) == current_function_decl)

511 {

…

523 }

524

525 /*When not in function-at-a-time mode, expand_end_bindings will

526 warnabout unused variables. But, in function-at-a-time mode

527 expand_end_bindings is not passed the list of variables in the

528 current scope, and therefore no warning is emitted. So, we

529 explicitly warn here. */

530 if (!processing_template_decl)

531 warn_about_unused_variables(getdecls ());

532

533 /*If there were any declarations or structure tags in that level,

534 or ifthis level is a function body,

535 createa BLOCK to record them for the life of this function. */

536 block = NULL_TREE;

…

550 /*We still support the old for-scope rules, whereby the variables

551 in afor-init statement were in scope after the for-statement

552 ended.We only use the new rules if flag_new_for_scope is

553 nonzero. */

554 leaving_for_scope

555 =current_binding_level->kind == sk_for && flag_new_for_scope == 1;

556

557 /*Remove declarations for all the DECLs in this level. */

558 for(link = decls; link; link = TREE_CHAIN (link))

559 {

560 if (leaving_for_scope&& TREE_CODE (link) == VAR_DECL

561 && DECL_NAME(link))

562 {

…

619 }

620 else

621 {

622 /*Remove the binding. */

623 decl = link;

624 if (TREE_CODE (decl) ==TREE_LIST)

625 decl = TREE_VALUE(decl);

626 if (DECL_P (decl))

627 pop_binding(DECL_NAME (decl), decl);

628 else if (TREE_CODE(decl) == OVERLOAD)

629 pop_binding(DECL_NAME (OVL_FUNCTION (decl)), decl);

630 else

631 abort ();

632 }

633 }

634

635 /*Remove declarations for any `for' variables from inner scopes

636 thatwe kept around. */

637 for(link = current_binding_level->dead_vars_from_for;

638 link; link = TREE_CHAIN(link))

639 pop_binding(DECL_NAME (TREE_VALUE (link)), TREE_VALUE (link));

640

641 /*Restore the IDENTIFIER_TYPE_VALUEs. */

642 for(link = current_binding_level->type_shadowed;

643 link; link = TREE_CHAIN(link))

644 SET_IDENTIFIER_TYPE_VALUE(TREE_PURPOSE (link), TREE_VALUE (link));

645

646 /*Restore the IDENTIFIER_LABEL_VALUEs for local labels. */

647 for(link = current_binding_level->shadowed_labels;

648 link;

649 link = TREE_CHAIN(link))

650 pop_label (TREE_VALUE(link), TREE_PURPOSE (link));

…

682 kind =current_binding_level->kind;

683

684 leave_scope();

…

722 POP_TIMEVAR_AND_RETURN(TV_NAME_LOOKUP, block);

723 }

As names field of the associated cxx_scope of the binding scoperecords the declarations within, and relevant IDENTIFIER_NODE has the bindingsfield to represent the binding between the name and the declaration in thescope. At exitting of the scope, it no doubt should remove these bindings. Thenit can safely jump up to the upper scope level.