From 6ecbea40195c91ce7b723f1f2514cbbfaea11b78 Mon Sep 17 00:00:00 2001
From: "Stephan T. Lavavej" <stl@nuwen.net>
Date: Thu, 7 Dec 2023 22:10:42 -0800
Subject: [PATCH 1/2] Fix range.split/adaptor.pass.cpp; only views::split('x')
 can be piped.

This was failing with:

D:\GitHub\STL\llvm-project\libcxx\test\std\ranges\range.adaptors\range.split\adaptor.pass.cpp(42,1): error: static assertion failed
static_assert( CanBePiped<SomeView&,    decltype(std::views::split)>);
^              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
D:\GitHub\STL\llvm-project\libcxx\test\std\ranges\range.adaptors\range.split\adaptor.pass.cpp(42,16): note: because 'CanBePiped<SomeView &, decltype(std::views::split)>' evaluated to false
static_assert( CanBePiped<SomeView&,    decltype(std::views::split)>);
               ^
D:\GitHub\STL\llvm-project\libcxx\test\std\ranges\range.adaptors\range.split\adaptor.pass.cpp(25,30): note: because 'std::forward<View>(view) | std::forward<T>(t)' would be invalid: invalid operands to binary expression ('SomeView' and 'const std::ranges::views::_Split_fn')
  { std::forward<View>(view) | std::forward<T>(t) };
                             ^
D:\GitHub\STL\llvm-project\libcxx\test\std\ranges\range.adaptors\range.split\adaptor.pass.cpp(43,1): error: static assertion failed
static_assert( CanBePiped<char(&)[10],  decltype(std::views::split)>);
^              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
D:\GitHub\STL\llvm-project\libcxx\test\std\ranges\range.adaptors\range.split\adaptor.pass.cpp(43,16): note: because 'CanBePiped<char (&)[10], decltype(std::views::split)>' evaluated to false
static_assert( CanBePiped<char(&)[10],  decltype(std::views::split)>);
               ^
D:\GitHub\STL\llvm-project\libcxx\test\std\ranges\range.adaptors\range.split\adaptor.pass.cpp(25,30): note: because 'std::forward<View>(view) | std::forward<T>(t)' would be invalid: invalid operands to binary expression ('char[10]' and 'const std::ranges::views::_Split_fn')
  { std::forward<View>(view) | std::forward<T>(t) };
                             ^

Similarly for range.lazy.split/adaptor.pass.cpp.
---
 .../range.adaptors/range.lazy.split/adaptor.pass.cpp      | 8 ++++----
 .../ranges/range.adaptors/range.split/adaptor.pass.cpp    | 8 ++++----
 2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/libcxx/test/std/ranges/range.adaptors/range.lazy.split/adaptor.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.lazy.split/adaptor.pass.cpp
index da4bd9fbbe179..aae5b6e54f648 100644
--- a/libcxx/test/std/ranges/range.adaptors/range.lazy.split/adaptor.pass.cpp
+++ b/libcxx/test/std/ranges/range.adaptors/range.lazy.split/adaptor.pass.cpp
@@ -40,10 +40,10 @@ static_assert(!std::is_invocable_v<decltype(std::views::lazy_split), SomeView, N
 static_assert(!std::is_invocable_v<decltype(std::views::lazy_split), NotAView, SomeView>);
 static_assert( std::is_invocable_v<decltype(std::views::lazy_split), SomeView, SomeView>);
 
-static_assert( CanBePiped<SomeView&,    decltype(std::views::lazy_split)>);
-static_assert( CanBePiped<char(&)[10],  decltype(std::views::lazy_split)>);
-static_assert(!CanBePiped<char(&&)[10], decltype(std::views::lazy_split)>);
-static_assert(!CanBePiped<NotAView,     decltype(std::views::lazy_split)>);
+static_assert(CanBePiped<SomeView&, decltype(std::views::lazy_split('x'))>);
+static_assert(CanBePiped<char (&)[10], decltype(std::views::lazy_split('x'))>);
+static_assert(!CanBePiped<char (&&)[10], decltype(std::views::lazy_split('x'))>);
+static_assert(!CanBePiped<NotAView, decltype(std::views::lazy_split('x'))>);
 
 static_assert(std::same_as<decltype(std::views::lazy_split), decltype(std::ranges::views::lazy_split)>);
 
diff --git a/libcxx/test/std/ranges/range.adaptors/range.split/adaptor.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.split/adaptor.pass.cpp
index cd12011daeab5..5bf2d56090e8f 100644
--- a/libcxx/test/std/ranges/range.adaptors/range.split/adaptor.pass.cpp
+++ b/libcxx/test/std/ranges/range.adaptors/range.split/adaptor.pass.cpp
@@ -39,10 +39,10 @@ static_assert(!std::is_invocable_v<decltype(std::views::split), SomeView, NotAVi
 static_assert(!std::is_invocable_v<decltype(std::views::split), NotAView, SomeView>);
 static_assert( std::is_invocable_v<decltype(std::views::split), SomeView, SomeView>);
 
-static_assert( CanBePiped<SomeView&,    decltype(std::views::split)>);
-static_assert( CanBePiped<char(&)[10],  decltype(std::views::split)>);
-static_assert(!CanBePiped<char(&&)[10], decltype(std::views::split)>);
-static_assert(!CanBePiped<NotAView,     decltype(std::views::split)>);
+static_assert(CanBePiped<SomeView&, decltype(std::views::split('x'))>);
+static_assert(CanBePiped<char (&)[10], decltype(std::views::split('x'))>);
+static_assert(!CanBePiped<char (&&)[10], decltype(std::views::split('x'))>);
+static_assert(!CanBePiped<NotAView, decltype(std::views::split('x'))>);
 
 static_assert(std::same_as<decltype(std::views::split), decltype(std::ranges::views::split)>);
 

From 97c2ccea21c776aeca56d52d5a9b5e5e59160c03 Mon Sep 17 00:00:00 2001
From: "Stephan T. Lavavej" <stl@nuwen.net>
Date: Tue, 12 Dec 2023 16:55:21 -0800
Subject: [PATCH 2/2] Fix product code, add regression test.

---
 libcxx/include/__ranges/lazy_split_view.h                   | 2 +-
 libcxx/include/__ranges/split_view.h                        | 2 +-
 .../ranges/range.adaptors/range.lazy.split/adaptor.pass.cpp | 6 ++++++
 .../std/ranges/range.adaptors/range.split/adaptor.pass.cpp  | 6 ++++++
 4 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/libcxx/include/__ranges/lazy_split_view.h b/libcxx/include/__ranges/lazy_split_view.h
index 2c654bfd325a6..8ed4bcfdeb56d 100644
--- a/libcxx/include/__ranges/lazy_split_view.h
+++ b/libcxx/include/__ranges/lazy_split_view.h
@@ -437,7 +437,7 @@ lazy_split_view(_Range&&, range_value_t<_Range>)
 
 namespace views {
 namespace __lazy_split_view {
-struct __fn : __range_adaptor_closure<__fn> {
+struct __fn {
   template <class _Range, class _Pattern>
   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI
   constexpr auto operator()(_Range&& __range, _Pattern&& __pattern) const
diff --git a/libcxx/include/__ranges/split_view.h b/libcxx/include/__ranges/split_view.h
index a27ac4ef7a196..7f03be3c346a4 100644
--- a/libcxx/include/__ranges/split_view.h
+++ b/libcxx/include/__ranges/split_view.h
@@ -194,7 +194,7 @@ struct split_view<_View, _Pattern>::__sentinel {
 
 namespace views {
 namespace __split_view {
-struct __fn : __range_adaptor_closure<__fn> {
+struct __fn {
   // clang-format off
   template <class _Range, class _Pattern>
   _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI
diff --git a/libcxx/test/std/ranges/range.adaptors/range.lazy.split/adaptor.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.lazy.split/adaptor.pass.cpp
index aae5b6e54f648..6bfa0ab487ba1 100644
--- a/libcxx/test/std/ranges/range.adaptors/range.lazy.split/adaptor.pass.cpp
+++ b/libcxx/test/std/ranges/range.adaptors/range.lazy.split/adaptor.pass.cpp
@@ -40,6 +40,12 @@ static_assert(!std::is_invocable_v<decltype(std::views::lazy_split), SomeView, N
 static_assert(!std::is_invocable_v<decltype(std::views::lazy_split), NotAView, SomeView>);
 static_assert( std::is_invocable_v<decltype(std::views::lazy_split), SomeView, SomeView>);
 
+// Regression test for #75002, views::lazy_split shouldn't be a range adaptor closure
+static_assert(!CanBePiped<SomeView&, decltype(std::views::lazy_split)>);
+static_assert(!CanBePiped<char (&)[10], decltype(std::views::lazy_split)>);
+static_assert(!CanBePiped<char (&&)[10], decltype(std::views::lazy_split)>);
+static_assert(!CanBePiped<NotAView, decltype(std::views::lazy_split)>);
+
 static_assert(CanBePiped<SomeView&, decltype(std::views::lazy_split('x'))>);
 static_assert(CanBePiped<char (&)[10], decltype(std::views::lazy_split('x'))>);
 static_assert(!CanBePiped<char (&&)[10], decltype(std::views::lazy_split('x'))>);
diff --git a/libcxx/test/std/ranges/range.adaptors/range.split/adaptor.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.split/adaptor.pass.cpp
index 5bf2d56090e8f..85d13ac5c29df 100644
--- a/libcxx/test/std/ranges/range.adaptors/range.split/adaptor.pass.cpp
+++ b/libcxx/test/std/ranges/range.adaptors/range.split/adaptor.pass.cpp
@@ -39,6 +39,12 @@ static_assert(!std::is_invocable_v<decltype(std::views::split), SomeView, NotAVi
 static_assert(!std::is_invocable_v<decltype(std::views::split), NotAView, SomeView>);
 static_assert( std::is_invocable_v<decltype(std::views::split), SomeView, SomeView>);
 
+// Regression test for #75002, views::split shouldn't be a range adaptor closure
+static_assert(!CanBePiped<SomeView&, decltype(std::views::split)>);
+static_assert(!CanBePiped<char (&)[10], decltype(std::views::split)>);
+static_assert(!CanBePiped<char (&&)[10], decltype(std::views::split)>);
+static_assert(!CanBePiped<NotAView, decltype(std::views::split)>);
+
 static_assert(CanBePiped<SomeView&, decltype(std::views::split('x'))>);
 static_assert(CanBePiped<char (&)[10], decltype(std::views::split('x'))>);
 static_assert(!CanBePiped<char (&&)[10], decltype(std::views::split('x'))>);