Added a set of nodes to represent requirements inside of a requires expression (EXPR_REQ, TYPE_REQ, NESTED_REQ), and a set of nodes representing the actual checks of those requirements (VALIDEXPR_EXPR, VALIDTYPE_EXPR, CONSTEXPR_EXPR).
The VALIDEXPR_EXPR, VALIDTYPE_EXPR, and CONSTEXPR_EXPR nodes are
essentially no different than TRAIT_EXPR or NOEXCEPT_EXPR nodes. They
evaluate properties of an operand.
This design is a little different than the previous implementation,
where I rendered the syntax directly into a conjunction of those
expressions.
I also added a nascent implementation of __is_convertible_to since
expression requirements include conversion requirements.
This patch does not include instantiation or decomposition rules. I
wanted to get the design reviewed before implementing the more
intricate stuff.
Changelog:
2013-06-24 Andrew Sutton <andrew.n.sut...@gmail.com>
* gcc/cp/cxx-pretty-print.c (pp_cxx_primary_expression): Pretty
print new expr/req nodes.
(pp_cxx_requires_expr): New along with related functions for
pretty printing requirements.
* gcc/cp/cxx-pretty-print.h (pp_cxx_requires_expr): New along with
related functions for pretty printing requirements.
* gcc/cp/semantics.c (convertible_to_p): Implement __is_convertible_to
type trait.
(trait_expr_value): Evaluate __is_convertible_to.
(finish_requires_expr): Implemented, along with other functions to
construct and evaluate nodes for template constraints.
* gcc/cp/parser.c (cp_parser_requires_expr): Update parser using new
requires expression nodes. Renamed some grammar productions to better
reflect the representation of the syntax.
(cp_parser_nested_requirement): Wrap results in a
NESTED_REQ node.
* gcc/cp/cp-tree.def: (REQUIRES_EXPR): New.
(EXPR_REQ): New.
(TYPE_REQ): New.
(NESTED_REQ): New.
(VALIDEXPR_EXPR): New.
(VALIDTYPE_EXPR): New.
(CONSTEXPR_EXPR): New.
* gcc/cp/cp-objcp-common.c (cp_common_init_ts): Make new nodes typed.
* gcc/cp/cp-tree.h (finish_expr_requirement): New.
(finish_type_requirement): New.
(finish_nested_requirement): New.
(finish_validexpr_expr): New.
(finish_validtype_expr): New.
(finish_constexpr_expr): New.
* gcc/cp/error.c: (dump_expr): Pretty print new nodes.
Andrew
reqexpr-2.patch
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