The contents of the <compare> header are not complete unless concepts
are supported, so the feature test macro should depend on the macro for
concepts.
As a result, the std::lexicographical_compare_three_way function will
not be defined unless concepts are supported, so there is no need to
check __cpp_lib_concepts before using concepts in those functions.
* include/bits/stl_algobase.h (__is_byte_iter, __min_cmp)
(lexicographical_compare_three_way): Do not depend on
__cpp_lib_concepts.
* include/std/version (__cpp_lib_three_way_comparison): Only define
when __cpp_lib_concepts is defined.
* libsupc++/compare (__cpp_lib_three_way_comparison): Likewise.
From-SVN: r279896
* libsupc++/compare (common_comparison_category): Define without using
concepts and optimise for compilation time.
(__detail::__cmp_cat_ids): Remove.
(__detail::__common_cmp_cat): Replace class template and
specializations with constexpr function.
From-SVN: r279307
This defines operator<=> as a non-member function template and does not
alter operator==. This contradicts the changes made by P1614R2, which
specify both as hidden friends, but that specification of operator<=> is
broken and the subject of a soon-to-be-published LWG issue.
* include/bits/stl_pair.h [__cpp_lib_three_way_comparison]
(operator<=>): Define for C++20.
* libsupc++/compare (__cmp2way_res_t): Rename to __cmp3way_res_t,
move into __detail namespace. Do not turn argument types into lvalues.
(__cmp3way_helper): Rename to __cmp3way_res_impl, move into __detail
namespace. Constrain with concepts instead of using void_t.
(compare_three_way_result): Adjust name of base class.
(compare_three_way_result_t): Use __cmp3way_res_impl directly.
(__detail::__3way_cmp_with): Add workaround for PR 91073.
(compare_three_way): Use workaround.
(__detail::__synth3way, __detail::__synth3way_t): Define new helpers
implementing synth-three-way and synth-three-way-result semantics.
* testsuite/20_util/pair/comparison_operators/constexpr_c++20.cc: New
test.
From-SVN: r278951
This is incomplete because std::strong_order doesn't support
floating-point types.
The partial_order and weak_order tests use VERIFY instead of
static_assert because of PR 92431.
* libsupc++/compare (strong_order, weak_order, partial_order)
(compare_strong_order_fallback, compare_weak_order_fallback)
(compare_partial_order_fallback): Define customization point objects
for C++20.
* testsuite/18_support/comparisons/algorithms/partial_order.cc: New
test.
* testsuite/18_support/comparisons/algorithms/strong_order.cc: New
test.
* testsuite/18_support/comparisons/algorithms/weak_order.cc: New test.
From-SVN: r278149
Shortly after I finished implementing the previous semantics, the
committee decided to remove the *_equality comparison categories, because
they were largely obsoleted by the earlier change that separated operator==
from its original dependency on operator<=>.
gcc/cp/
* method.c (enum comp_cat_tag, comp_cat_info): Remove *_equality.
(genericize_spaceship, common_comparison_type): Likewise.
* typeck.c (cp_build_binary_op): Move SPACESHIP_EXPR to be with the
relational operators, exclude other types no longer supported.
libstdc++-v3/
* libsupc++/compare: Remove strong_equality and weak_equality.
From-SVN: r277925
There are three major pieces to this support: scalar operator<=>,
synthesis of comparison operators, and rewritten/reversed overload
resolution (e.g. a < b becomes 0 > b <=> a).
Unlike other defaulted functions, where we use synthesized_method_walk to
semi-simulate what the definition of the function will be like, this patch
determines the characteristics of a comparison operator by trying to define
it.
My handling of non-dependent rewritten operators in templates can still use
some work: build_min_non_dep_op_overload can't understand the rewrites and
crashes, so I'm avoiding it for now by clearing *overload. This means we'll
do name lookup again at instantiation time, which can incorrectly mean a
different result. I'll poke at this more in stage 3.
I'm leaving out a fourth section ("strong structural equality") even though
I've implemented it, because it seems likely to change radically tomorrow.
Thanks to Tim van Deurzen and Jakub for implementing lexing of the <=>
operator, and Jonathan for the initial <compare> header.
gcc/cp/
* cp-tree.h (struct lang_decl_fn): Add maybe_deleted bitfield.
(DECL_MAYBE_DELETED): New.
(enum special_function_kind): Add sfk_comparison.
(LOOKUP_REWRITTEN, LOOKUP_REVERSED): New.
* call.c (struct z_candidate): Add rewritten and reversed methods.
(add_builtin_candidate): Handle SPACESHIP_EXPR.
(add_builtin_candidates): Likewise.
(add_candidates): Don't add a reversed candidate if the parms are
the same.
(add_operator_candidates): Split out from build_new_op_1. Handle
rewritten and reversed candidates.
(add_candidate): Swap conversions of reversed candidate.
(build_new_op_1): Swap them back. Build a second operation for
rewritten candidates.
(extract_call_expr): Handle rewritten calls.
(same_fn_or_template): New.
(joust): Handle rewritten and reversed candidates.
* class.c (add_implicitly_declared_members): Add implicit op==.
(classtype_has_op, classtype_has_defaulted_op): New.
* constexpr.c (cxx_eval_binary_expression): Handle SPACESHIP_EXPR.
(cxx_eval_constant_expression, potential_constant_expression_1):
Likewise.
* cp-gimplify.c (genericize_spaceship): New.
(cp_genericize_r): Use it.
* cp-objcp-common.c (cp_common_init_ts): Handle SPACESHIP_EXPR.
* decl.c (finish_function): Handle deleted function.
* decl2.c (grokfield): SET_DECL_FRIEND_CONTEXT on defaulted friend.
(mark_used): Check DECL_MAYBE_DELETED. Remove assumption that
defaulted functions are non-static members.
* error.c (dump_expr): Handle SPACESHIP_EXPR.
* method.c (type_has_trivial_fn): False for sfk_comparison.
(enum comp_cat_tag, struct comp_cat_info_t): New types.
(comp_cat_cache): New array variable.
(lookup_comparison_result, lookup_comparison_category)
(is_cat, cat_tag_for, spaceship_comp_cat)
(spaceship_type, genericize_spaceship)
(common_comparison_type, early_check_defaulted_comparison)
(comp_info, build_comparison_op): New.
(synthesize_method): Handle sfk_comparison. Handle deleted.
(get_defaulted_eh_spec, maybe_explain_implicit_delete)
(explain_implicit_non_constexpr, implicitly_declare_fn)
(defaulted_late_check, defaultable_fn_check): Handle sfk_comparison.
* name-lookup.c (get_std_name_hint): Add comparison categories.
* tree.c (special_function_p): Add sfk_comparison.
* typeck.c (cp_build_binary_op): Handle SPACESHIP_EXPR.
2019-11-05 Tim van Deurzen <tim@kompiler.org>
Add new tree code for the spaceship operator.
gcc/cp/
* cp-tree.def: Add new tree code.
* operators.def: New binary operator.
* parser.c: Add new token and tree code.
libcpp/
* cpplib.h: Add spaceship operator for C++.
* lex.c: Implement conditional lexing of spaceship operator for C++20.
2019-11-05 Jonathan Wakely <jwakely@redhat.com>
libstdc++-v3/
* libsupc++/compare: New header.
* libsupc++/Makefile.am (std_HEADERS): Add compare.
* include/std/version: Define __cpp_lib_three_way_comparison.
* include/std/functional: #include <compare>.
From-SVN: r277865
Jonathan Wakely
Jakub Jelinek
Jason Merrill
Jason Merrill