PR c++/91369 - Implement P0784R7: constexpr new

PR c++/91369 - Implement P0784R7: constexpr new

	PR c++/91369 - Implement P0784R7: constexpr new
c-family/
	* c-cppbuiltin.c (c_cpp_builtins): Predefine
	__cpp_constexpr_dynamic_alloc=201907 for -std=c++2a.
cp/
	* cp-tree.h (enum cp_tree_index): Add CPTI_HEAP_UNINIT_IDENTIFIER,
	CPTI_HEAP_IDENTIFIER and CPTI_HEAP_DELETED_IDENTIFIER.
	(heap_uninit_identifier, heap_identifier, heap_deleted_identifier):
	Define.
	(type_has_constexpr_destructor, build_new_constexpr_heap_type,
	cxx_constant_dtor): Declare.
	* class.c (type_maybe_constexpr_default_constructor): Make static.
	(type_maybe_constexpr_destructor, type_has_constexpr_destructor): New
	functions.
	(finalize_literal_type_property): For c++2a, don't clear
	CLASSTYPE_LITERAL_P for types without trivial destructors unless they
	have non-constexpr destructors.
	(explain_non_literal_class): For c++2a, complain about non-constexpr
	destructors rather than about non-trivial destructors.
	* constexpr.c: Include stor-layout.h.
	(struct constexpr_global_ctx): New type.
	(struct constexpr_ctx): Add global field, remove values and
	constexpr_ops_count.
	(cxx_replaceable_global_alloc_fn): New inline function.
	(cxx_eval_call_expression): For c++2a allow calls to replaceable
	global allocation functions, for new return address of a heap uninit
	var, for delete record its deletion.  Change ctx->values->{get,put} to
	ctx->global->values.{get,put}.
	(non_const_var_error): Add auto_diagnostic_group sentinel.  Emit
	special diagnostics for heap variables.
	(cxx_eval_store_expression): Change ctx->values->{get,put} to
	ctx->global->values.{get,put}.
	(cxx_eval_loop_expr): Initialize jump_target if NULL.  Change
	new_ctx.values->remove to ctx->global->values.remove.
	(cxx_eval_constant_expression): Change *ctx->constexpr_ops_count
	to ctx->global->constexpr_ops_count.  Change ctx->values->{get,put} to
	ctx->global->values.{get,put}.
	<case NOP_EXPR>: Formatting fix.  On cast of replaceable global
	allocation function to some pointer type, adjust the type of
	the heap variable and change name from heap_uninit_identifier
	to heap_identifier.
	(find_heap_var_refs): New function.
	(cxx_eval_outermost_constant_expr): Add constexpr_dtor argument,
	handle evaluation of constexpr dtors and add tracking of heap
	variables.  Use tf_no_cleanup for get_target_expr_with_sfinae.
	(cxx_constant_value): Adjust cxx_eval_outermost_constant_expr caller.
	(cxx_constant_dtor): New function.
	(maybe_constant_value, fold_non_dependent_expr_template,
	maybe_constant_init_1): Adjust cxx_eval_outermost_constant_expr
	callers.
	(potential_constant_expression_1): Ignore clobbers.  Allow
	COND_EXPR_IS_VEC_DELETE for c++2a.
	* decl.c (initialize_predefined_identifiers): Add heap identifiers.
	(decl_maybe_constant_destruction): New function.
	(cp_finish_decl): Don't clear TREE_READONLY for constexpr variables
	with non-trivial, but constexpr destructors.
	(register_dtor_fn): For constexpr variables with constexpr non-trivial
	destructors call cxx_maybe_build_cleanup instead of adding destructor
	calls at runtime.
	(expand_static_init): For constexpr variables with constexpr
	non-trivial destructors call cxx_maybe_build_cleanup.
	(grokdeclarator): Allow constexpr destructors for c++2a.  Formatting
	fix.
	(cxx_maybe_build_cleanup): For constexpr variables with constexpr
	non-trivial destructors call cxx_constant_dtor instead of adding
	destructor calls at runtime.
	* init.c: Include stor-layout.h.
	(build_new_constexpr_heap_type, maybe_wrap_new_for_constexpr): New
	functions.
	(build_new_1): For c++2a and new[], add cast around the alloc call
	to help constexpr evaluation figure out the type of the heap storage.
	(build_vec_delete_1): Set DECL_INITIAL of tbase and emit a DECL_EXPR
	for it instead of initializing an uninitialized variable.
	* method.c: Include intl.h.
	(SFK_CTOR_P, SFK_DTOR_P, SFK_ASSIGN_P, SFK_COPY_P, SFK_MOVE_P): Move
	definitions earlier.
	(process_subob_fn): Add sfk argument, adjust non-constexpr call
	diagnostics based on it.
	(walk_field_subobs): Formatting fixes.  Adjust process_subob_fn caller.
	(synthesized_method_base_walk): Likewise.
	(synthesized_method_walk): Set *constexpr_p to true for dtors in c++2a.
	Fix up DR number in comment.
	(implicitly_declare_fn): Formatting fix.
	* typeck2.c (store_init_value): Don't call cp_fully_fold_init on
	initializers of automatic non-constexpr variables in constexpr
	functions.
testsuite/
	* g++.dg/cpp0x/constexpr-delete2.C: Adjust expected diagnostics for
	c++2a.
	* g++.dg/cpp0x/locations1.C: Only expect constexpr ~S() diagnostics
	in c++17_down, adjust expected wording.
	* g++.dg/cpp1y/constexpr-new.C: Only expect diagnostics in c++17_down.
	* g++.dg/cpp2a/constexpr-dtor1.C: New test.
	* g++.dg/cpp2a/constexpr-dtor2.C: New test.
	* g++.dg/cpp2a/constexpr-dtor3.C: New test.
	* g++.dg/cpp2a/constexpr-new1.C: New test.
	* g++.dg/cpp2a/constexpr-new2.C: New test.
	* g++.dg/cpp2a/constexpr-new3.C: New test.
	* g++.dg/cpp2a/constexpr-new4.C: New test.
	* g++.dg/cpp2a/feat-cxx2a.C: Add __cpp_constinit and
	__cpp_constexpr_dynamic_alloc tests.  Tweak __cpp_* tests for c++2a
	features to use style like older features, including #ifdef test.
	* g++.dg/ext/is_literal_type3.C: New test.

From-SVN: r276622