This patch makes the C++ frontend work with the verify_type_context hook.
We need some new type contexts for features that don't exist in C, but
otherwise the patch is very similar to the C one.

TCTX_CAPTURE_BY_COPY could really be treated as an instance of
TCTX_FIELD, but the error message is better if we split it out.

2019-12-06  Richard Sandiford  <richard.sandiford@arm.com>

gcc/
	* target.h (TCTX_ALLOCATION, TCTX_DEALLOCATION, TCTX_EXCEPTIONS)
	(TCTX_CAPTURE_BY_COPY): New type_context_kinds.
	* config/aarch64/aarch64-sve-builtins.cc (verify_type_context):
	Handle them.

gcc/cp/
	* decl.c (start_decl_1): Use verify_type_context to check whether
	the target allows variables of a particular type to have static
	or thread-local storage duration.
	(check_array_initializer): Use verify_type_context to check whether
	the target allows a particular type to be used as an array element.
	(create_array_type_for_decl): Likewise.
	(cp_finish_decl): Use verify_type_context to check whether
	the target allows static member variables of a particular type.
	(grokdeclarator): Likewise.  Also use verify_type_context to check
	whether the target allows non-static member variables of a particular
	type.
	* except.c: Include target.h.
	(is_admissible_throw_operand_or_catch_parameter): Use
	verify_type_context to check whether the target allows particular
	types to be thrown and caught.
	* typeck2.c (add_exception_specifier): Likewise.
	* init.c (build_new_1): Use verify_type_context to check whether
	the target allows particular types to be dynamically allocated.
	(build_vec_delete_1, build_delete): Use verify_type_context to check
	whether the target allows particular types to be deleted.
	* lambda.c (add_capture): Use verify_type_context to check
	whether the target allows particular types to be captured by copy.
	* pt.c: Include target.h.
	(instantiate_class_template_1): Use verify_type_context to check
	whether the target allows non-static member variables of a particular
	type.
	* typeck.c (cxx_alignof_expr): Use verify_type_context to check
	whether the target allows the alignment of a particular type
	to be measured.
	(pointer_diff, cp_build_unary_op): Use verify_type_context to check
	whether the target allows arithmetic involving pointers to particular
	types.

gcc/testsuite/
	* g++.dg/ext/sve-sizeless-1.C: New test.
	* g++.dg/ext/sve-sizeless-2.C: Likewise.

From-SVN: r279058