[libc++] Eliminate the __function_like helper.

As prefigured in the comments on D115315.
This gives us one unified style for all niebloids,
and also simplifies the modulemap.

Differential Revision: https://reviews.llvm.org/D116570

libcxx/include/CMakeLists.txt

@@ -182,7 +182,6 @@ set(files
   __format/formatter_integral.h
   __format/formatter_string.h
   __format/parser_std_format_spec.h
-  __function_like.h
   __functional/binary_function.h
   __functional/binary_negate.h
   __functional/bind.h

libcxx/include/__iterator/advance.h

@@ -12,7 +12,6 @@
 
 #include <__config>
 #include <__debug>
-#include <__function_like.h>
 #include <__iterator/concepts.h>
 #include <__iterator/incrementable_traits.h>
 #include <__iterator/iterator_traits.h>
@@ -72,7 +71,7 @@ void advance(_InputIter& __i, _Distance __orig_n) {
 namespace ranges {
 namespace __advance {
 
-struct __fn final : private __function_like {
+struct __fn {
 private:
   template <class _Tp>
   _LIBCPP_HIDE_FROM_ABI
@@ -99,8 +98,6 @@ struct __fn final : private __function_like {
   }
 
 public:
-  constexpr explicit __fn(__tag __x) noexcept : __function_like(__x) {}
-
   // Preconditions: If `I` does not model `bidirectional_iterator`, `n` is not negative.
   template <input_or_output_iterator _Ip>
   _LIBCPP_HIDE_FROM_ABI
@@ -191,7 +188,7 @@ struct __fn final : private __function_like {
 } // namespace __advance
 
 inline namespace __cpo {
-  inline constexpr auto advance = __advance::__fn(__function_like::__tag());
+  inline constexpr auto advance = __advance::__fn{};
 } // namespace __cpo
 } // namespace ranges
 

libcxx/include/__iterator/next.h

@@ -12,7 +12,6 @@
 
 #include <__config>
 #include <__debug>
-#include <__function_like.h>
 #include <__iterator/advance.h>
 #include <__iterator/concepts.h>
 #include <__iterator/incrementable_traits.h>
@@ -43,10 +42,7 @@ inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
 namespace ranges {
 namespace __next {
 
-struct __fn final : private __function_like {
-  _LIBCPP_HIDE_FROM_ABI
-  constexpr explicit __fn(__tag __x) noexcept : __function_like(__x) {}
-
+struct __fn {
   template <input_or_output_iterator _Ip>
   _LIBCPP_HIDE_FROM_ABI
   constexpr _Ip operator()(_Ip __x) const {
@@ -79,7 +75,7 @@ struct __fn final : private __function_like {
 } // namespace __next
 
 inline namespace __cpo {
-  inline constexpr auto next = __next::__fn(__function_like::__tag());
+  inline constexpr auto next = __next::__fn{};
 } // namespace __cpo
 } // namespace ranges
 

libcxx/include/__iterator/prev.h

@@ -12,7 +12,6 @@
 
 #include <__config>
 #include <__debug>
-#include <__function_like.h>
 #include <__iterator/advance.h>
 #include <__iterator/concepts.h>
 #include <__iterator/incrementable_traits.h>
@@ -42,10 +41,7 @@ inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
 namespace ranges {
 namespace __prev {
 
-struct __fn final : private __function_like {
-  _LIBCPP_HIDE_FROM_ABI
-  constexpr explicit __fn(__tag __x) noexcept : __function_like(__x) {}
-
+struct __fn {
   template <bidirectional_iterator _Ip>
   _LIBCPP_HIDE_FROM_ABI
   constexpr _Ip operator()(_Ip __x) const {
@@ -71,7 +67,7 @@ struct __fn final : private __function_like {
 } // namespace __prev
 
 inline namespace __cpo {
-  inline constexpr auto prev = __prev::__fn(__function_like::__tag());
+  inline constexpr auto prev = __prev::__fn{};
 } // namespace __cpo
 } // namespace ranges
 

libcxx/include/__memory/ranges_construct_at.h

@@ -12,7 +12,6 @@
 
 #include <__concepts/destructible.h>
 #include <__config>
-#include <__function_like.h>
 #include <__iterator/incrementable_traits.h>
 #include <__iterator/readable_traits.h>
 #include <__memory/concepts.h>
@@ -37,9 +36,7 @@ namespace ranges {
 
 namespace __construct_at {
 
-struct __fn final : private __function_like {
-  _LIBCPP_HIDE_FROM_ABI constexpr explicit __fn(__tag __x) noexcept : __function_like(__x) {}
-
+struct __fn {
   template<class _Tp, class... _Args, class = decltype(
     ::new (declval<void*>()) _Tp(declval<_Args>()...)
   )>
@@ -52,16 +49,14 @@ struct __fn final : private __function_like {
 } // namespace __construct_at
 
 inline namespace __cpo {
-  inline constexpr auto construct_at = __construct_at::__fn(__function_like::__tag());
+  inline constexpr auto construct_at = __construct_at::__fn{};
 } // namespace __cpo
 
 // destroy_at
 
 namespace __destroy_at {
 
-struct __fn final : private __function_like {
-  _LIBCPP_HIDE_FROM_ABI constexpr explicit __fn(__tag __x) noexcept : __function_like(__x) {}
-
+struct __fn {
   template <destructible _Tp>
   _LIBCPP_HIDE_FROM_ABI
   constexpr void operator()(_Tp* __location) const noexcept {
@@ -72,16 +67,14 @@ struct __fn final : private __function_like {
 } // namespace __destroy_at
 
 inline namespace __cpo {
-  inline constexpr auto destroy_at = __destroy_at::__fn(__function_like::__tag());
+  inline constexpr auto destroy_at = __destroy_at::__fn{};
 } // namespace __cpo
 
 // destroy
 
 namespace __destroy {
 
-struct __fn final : private __function_like {
-  _LIBCPP_HIDE_FROM_ABI constexpr explicit __fn(__tag __x) noexcept : __function_like(__x) {}
-
+struct __fn {
   template <__nothrow_input_iterator _InputIterator, __nothrow_sentinel_for<_InputIterator> _Sentinel>
     requires destructible<iter_value_t<_InputIterator>>
   _LIBCPP_HIDE_FROM_ABI
@@ -100,16 +93,14 @@ struct __fn final : private __function_like {
 } // namespace __destroy
 
 inline namespace __cpo {
-  inline constexpr auto destroy = __destroy::__fn(__function_like::__tag());
+  inline constexpr auto destroy = __destroy::__fn{};
 } // namespace __cpo
 
 // destroy_n
 
 namespace __destroy_n {
 
-struct __fn final : private __function_like {
-  _LIBCPP_HIDE_FROM_ABI constexpr explicit __fn(__tag __x) noexcept : __function_like(__x) {}
-
+struct __fn {
   template <__nothrow_input_iterator _InputIterator>
     requires destructible<iter_value_t<_InputIterator>>
   _LIBCPP_HIDE_FROM_ABI
@@ -121,10 +112,11 @@ struct __fn final : private __function_like {
 } // namespace __destroy_n
 
 inline namespace __cpo {
-  inline constexpr auto destroy_n = __destroy_n::__fn(__function_like::__tag());
+  inline constexpr auto destroy_n = __destroy_n::__fn{};
 } // namespace __cpo
 
 } // namespace ranges
+
 #endif // !defined(_LIBCPP_HAS_NO_RANGES)
 
 _LIBCPP_END_NAMESPACE_STD