[libcxx-commits] [libcxx] Adds back special-case for booleans in std::variant gated by _LIBCPP_ENABLE_NARROWING_CONVERSIONS_IN_VARIANT. (PR #73121)
Louis Dionne via libcxx-commits
libcxx-commits at lists.llvm.org
Wed Nov 22 11:01:24 PST 2023
https://github.com/ldionne updated https://github.com/llvm/llvm-project/pull/73121
>From 8d5b02af08f892d9485a5c8de7c17c92baf4321b Mon Sep 17 00:00:00 2001
From: Bogdan Graur <bgraur at google.com>
Date: Wed, 22 Nov 2023 13:45:11 +0000
Subject: [PATCH 1/3] Adds back special-case for booleans in std::variant gated
by _LIBCPP_ENABLE_NARROWING_CONVERSIONS_IN_VARIANT.
---
libcxx/docs/Status/Cxx20Papers.csv | 2 +-
libcxx/include/variant | 18 ++++++++++++++++++
.../variant.variant/variant.assign/T.pass.cpp | 9 +++++++++
.../variant.assign/conv.pass.cpp | 7 ++++++-
.../variant.variant/variant.ctor/T.pass.cpp | 9 +++++++++
.../variant.variant/variant.ctor/conv.pass.cpp | 7 ++++++-
6 files changed, 49 insertions(+), 3 deletions(-)
diff --git a/libcxx/docs/Status/Cxx20Papers.csv b/libcxx/docs/Status/Cxx20Papers.csv
index 7aff860c68cf98e..cf7cf7f6dbdef0c 100644
--- a/libcxx/docs/Status/Cxx20Papers.csv
+++ b/libcxx/docs/Status/Cxx20Papers.csv
@@ -173,7 +173,7 @@
"`P1868R2 <https://wg21.link/P1868R2>`__","LWG","width: clarifying units of width and precision in std::format","Prague","|Complete|","14.0"
"`P1937R2 <https://wg21.link/P1937R2>`__","CWG","Fixing inconsistencies between constexpr and consteval functions","Prague","* *",""
"`P1956R1 <https://wg21.link/P1956R1>`__","LWG","On the names of low-level bit manipulation functions","Prague","|Complete|","12.0"
-"`P1957R2 <https://wg21.link/P1957R2>`__","CWG","Converting from ``T*``\ to bool should be considered narrowing (re: US 212)","Prague","|Complete|","18.0"
+"`P1957R2 <https://wg21.link/P1957R2>`__","CWG","Converting from ``T*``\ to bool should be considered narrowing (re: US 212)","Prague","* *",""
"`P1963R0 <https://wg21.link/P1963R0>`__","LWG","Fixing US 313","Prague","* *","",""
"`P1964R2 <https://wg21.link/P1964R2>`__","LWG","Wording for boolean-testable","Prague","|Complete|","13.0"
"`P1970R2 <https://wg21.link/P1970R2>`__","LWG","Consistency for size() functions: Add ranges::ssize","Prague","|Complete|","15.0","|ranges|"
diff --git a/libcxx/include/variant b/libcxx/include/variant
index d89c0596b1db0de..414cdc8b85469df 100644
--- a/libcxx/include/variant
+++ b/libcxx/include/variant
@@ -1252,6 +1252,24 @@ struct __overload {
auto operator()(_Tp, _Up&&) const -> __check_for_narrowing<_Tp, _Up>;
};
+#ifdef _LIBCPP_ENABLE_NARROWING_CONVERSIONS_IN_VARIANT
+template <class _Tp, size_t>
+struct __overload_bool {
+ template <class _Up, class _Ap = __remove_cvref_t<_Up>>
+ auto operator()(bool, _Up&&) const
+ -> enable_if_t<is_same_v<_Ap, bool>, __type_identity<_Tp>>;
+};
+
+template <size_t _Idx>
+struct __overload<bool, _Idx> : __overload_bool<bool, _Idx> {};
+template <size_t _Idx>
+struct __overload<bool const, _Idx> : __overload_bool<bool const, _Idx> {};
+template <size_t _Idx>
+struct __overload<bool volatile, _Idx> : __overload_bool<bool volatile, _Idx> {};
+template <size_t _Idx>
+struct __overload<bool const volatile, _Idx> : __overload_bool<bool const volatile, _Idx> {};
+#endif
+
template <class ..._Bases>
struct __all_overloads : _Bases... {
void operator()() const;
diff --git a/libcxx/test/std/utilities/variant/variant.variant/variant.assign/T.pass.cpp b/libcxx/test/std/utilities/variant/variant.variant/variant.assign/T.pass.cpp
index c63626090c2fe9a..de9853f6930c6df 100644
--- a/libcxx/test/std/utilities/variant/variant.variant/variant.assign/T.pass.cpp
+++ b/libcxx/test/std/utilities/variant/variant.variant/variant.assign/T.pass.cpp
@@ -146,8 +146,13 @@ void test_T_assignment_sfinae() {
};
static_assert(!std::is_assignable<V, X>::value,
"no boolean conversion in operator=");
+#if defined(_LIBCPP_ENABLE_NARROWING_CONVERSIONS_IN_VARIANT)
+ static_assert(!std::is_assignable<V, std::false_type>::value,
+ "no converted to bool in operator=");
+#else
static_assert(std::is_assignable<V, std::false_type>::value,
"converted to bool in operator=");
+#endif
}
{
struct X {};
@@ -296,6 +301,7 @@ void test_T_assignment_performs_assignment() {
#endif // TEST_HAS_NO_EXCEPTIONS
}
+#if !defined(_LIBCPP_ENABLE_NARROWING_CONVERSIONS_IN_VARIANT)
void test_T_assignment_vector_bool() {
std::vector<bool> vec = {true};
std::variant<bool, int> v;
@@ -303,6 +309,7 @@ void test_T_assignment_vector_bool() {
assert(v.index() == 0);
assert(std::get<0>(v) == true);
}
+#endif
int main(int, char**) {
test_T_assignment_basic();
@@ -310,7 +317,9 @@ int main(int, char**) {
test_T_assignment_performs_assignment();
test_T_assignment_noexcept();
test_T_assignment_sfinae();
+#if !defined(_LIBCPP_ENABLE_NARROWING_CONVERSIONS_IN_VARIANT)
test_T_assignment_vector_bool();
+#endif
return 0;
}
diff --git a/libcxx/test/std/utilities/variant/variant.variant/variant.assign/conv.pass.cpp b/libcxx/test/std/utilities/variant/variant.variant/variant.assign/conv.pass.cpp
index d93d429e262c05b..f927db744e297c8 100644
--- a/libcxx/test/std/utilities/variant/variant.variant/variant.assign/conv.pass.cpp
+++ b/libcxx/test/std/utilities/variant/variant.variant/variant.assign/conv.pass.cpp
@@ -33,8 +33,13 @@ int main(int, char**)
static_assert(!std::is_assignable<std::variant<int, bool>, decltype("meow")>::value, "");
static_assert(!std::is_assignable<std::variant<int, const bool>, decltype("meow")>::value, "");
-
+#if defined(_LIBCPP_ENABLE_NARROWING_CONVERSIONS_IN_VARIANT)
+ static_assert(!std::is_assignable<std::variant<int, const volatile bool>, decltype("meow")>::value, "");
+ static_assert(!std::is_assignable<std::variant<bool>, std::true_type>::value, "");
+#else
static_assert(std::is_assignable<std::variant<bool>, std::true_type>::value, "");
+#endif
+
static_assert(!std::is_assignable<std::variant<bool>, std::unique_ptr<char> >::value, "");
static_assert(!std::is_assignable<std::variant<bool>, decltype(nullptr)>::value, "");
diff --git a/libcxx/test/std/utilities/variant/variant.variant/variant.ctor/T.pass.cpp b/libcxx/test/std/utilities/variant/variant.variant/variant.ctor/T.pass.cpp
index 04329f4f412b06a..4a0a31fdf320e66 100644
--- a/libcxx/test/std/utilities/variant/variant.variant/variant.ctor/T.pass.cpp
+++ b/libcxx/test/std/utilities/variant/variant.variant/variant.ctor/T.pass.cpp
@@ -80,8 +80,13 @@ void test_T_ctor_sfinae() {
};
static_assert(!std::is_constructible<V, X>::value,
"no boolean conversion in constructor");
+#if defined(_LIBCPP_ENABLE_NARROWING_CONVERSIONS_IN_VARIANT)
+ static_assert(!std::is_constructible<V, std::false_type>::value,
+ "no converted to bool in constructor");
+#else
static_assert(std::is_constructible<V, std::false_type>::value,
"converted to bool in constructor");
+#endif
}
{
struct X {};
@@ -199,12 +204,14 @@ void test_construction_with_repeated_types() {
static_assert(std::is_constructible<V, Bar>::value, "");
}
+#if !defined(_LIBCPP_ENABLE_NARROWING_CONVERSIONS_IN_VARIANT)
void test_vector_bool() {
std::vector<bool> vec = {true};
std::variant<bool, int> v = vec[0];
assert(v.index() == 0);
assert(std::get<0>(v) == true);
}
+#endif
int main(int, char**) {
test_T_ctor_basic();
@@ -212,6 +219,8 @@ int main(int, char**) {
test_T_ctor_sfinae();
test_no_narrowing_check_for_class_types();
test_construction_with_repeated_types();
+#if !defined(_LIBCPP_ENABLE_NARROWING_CONVERSIONS_IN_VARIANT)
test_vector_bool();
+#endif
return 0;
}
diff --git a/libcxx/test/std/utilities/variant/variant.variant/variant.ctor/conv.pass.cpp b/libcxx/test/std/utilities/variant/variant.variant/variant.ctor/conv.pass.cpp
index 7a4c68b5dacca7f..e4ee27a614f35d9 100644
--- a/libcxx/test/std/utilities/variant/variant.variant/variant.ctor/conv.pass.cpp
+++ b/libcxx/test/std/utilities/variant/variant.variant/variant.ctor/conv.pass.cpp
@@ -32,8 +32,13 @@ int main(int, char**)
static_assert(!std::is_constructible<std::variant<int, bool>, decltype("meow")>::value, "");
static_assert(!std::is_constructible<std::variant<int, const bool>, decltype("meow")>::value, "");
-
+#if defined(_LIBCPP_ENABLE_NARROWING_CONVERSIONS_IN_VARIANT)
+ static_assert(!std::is_constructible<std::variant<int, const volatile bool>, decltype("meow")>::value, "");
+ static_assert(!std::is_constructible<std::variant<bool>, std::true_type>::value, "");
+#else
static_assert(std::is_constructible<std::variant<bool>, std::true_type>::value, "");
+#endif
+
static_assert(!std::is_constructible<std::variant<bool>, std::unique_ptr<char> >::value, "");
static_assert(!std::is_constructible<std::variant<bool>, decltype(nullptr)>::value, "");
>From da527bbfca9272a68c8b9e78baea980394b14aac Mon Sep 17 00:00:00 2001
From: Bogdan Graur <bgraur at google.com>
Date: Wed, 22 Nov 2023 15:55:44 +0000
Subject: [PATCH 2/3] code review adjustments.
---
libcxx/docs/Status/Cxx20Papers.csv | 2 +-
.../variant/variant.variant/variant.assign/T.pass.cpp | 8 +++-----
.../variant/variant.variant/variant.assign/conv.pass.cpp | 2 +-
.../variant/variant.variant/variant.ctor/T.pass.cpp | 8 +++-----
.../variant/variant.variant/variant.ctor/conv.pass.cpp | 2 +-
5 files changed, 9 insertions(+), 13 deletions(-)
diff --git a/libcxx/docs/Status/Cxx20Papers.csv b/libcxx/docs/Status/Cxx20Papers.csv
index cf7cf7f6dbdef0c..7aff860c68cf98e 100644
--- a/libcxx/docs/Status/Cxx20Papers.csv
+++ b/libcxx/docs/Status/Cxx20Papers.csv
@@ -173,7 +173,7 @@
"`P1868R2 <https://wg21.link/P1868R2>`__","LWG","width: clarifying units of width and precision in std::format","Prague","|Complete|","14.0"
"`P1937R2 <https://wg21.link/P1937R2>`__","CWG","Fixing inconsistencies between constexpr and consteval functions","Prague","* *",""
"`P1956R1 <https://wg21.link/P1956R1>`__","LWG","On the names of low-level bit manipulation functions","Prague","|Complete|","12.0"
-"`P1957R2 <https://wg21.link/P1957R2>`__","CWG","Converting from ``T*``\ to bool should be considered narrowing (re: US 212)","Prague","* *",""
+"`P1957R2 <https://wg21.link/P1957R2>`__","CWG","Converting from ``T*``\ to bool should be considered narrowing (re: US 212)","Prague","|Complete|","18.0"
"`P1963R0 <https://wg21.link/P1963R0>`__","LWG","Fixing US 313","Prague","* *","",""
"`P1964R2 <https://wg21.link/P1964R2>`__","LWG","Wording for boolean-testable","Prague","|Complete|","13.0"
"`P1970R2 <https://wg21.link/P1970R2>`__","LWG","Consistency for size() functions: Add ranges::ssize","Prague","|Complete|","15.0","|ranges|"
diff --git a/libcxx/test/std/utilities/variant/variant.variant/variant.assign/T.pass.cpp b/libcxx/test/std/utilities/variant/variant.variant/variant.assign/T.pass.cpp
index de9853f6930c6df..e0782a05efcfdc5 100644
--- a/libcxx/test/std/utilities/variant/variant.variant/variant.assign/T.pass.cpp
+++ b/libcxx/test/std/utilities/variant/variant.variant/variant.assign/T.pass.cpp
@@ -146,7 +146,7 @@ void test_T_assignment_sfinae() {
};
static_assert(!std::is_assignable<V, X>::value,
"no boolean conversion in operator=");
-#if defined(_LIBCPP_ENABLE_NARROWING_CONVERSIONS_IN_VARIANT)
+#ifdef _LIBCPP_ENABLE_NARROWING_CONVERSIONS_IN_VARIANT
static_assert(!std::is_assignable<V, std::false_type>::value,
"no converted to bool in operator=");
#else
@@ -301,15 +301,15 @@ void test_T_assignment_performs_assignment() {
#endif // TEST_HAS_NO_EXCEPTIONS
}
-#if !defined(_LIBCPP_ENABLE_NARROWING_CONVERSIONS_IN_VARIANT)
void test_T_assignment_vector_bool() {
+#ifndef _LIBCPP_ENABLE_NARROWING_CONVERSIONS_IN_VARIANT
std::vector<bool> vec = {true};
std::variant<bool, int> v;
v = vec[0];
assert(v.index() == 0);
assert(std::get<0>(v) == true);
-}
#endif
+}
int main(int, char**) {
test_T_assignment_basic();
@@ -317,9 +317,7 @@ int main(int, char**) {
test_T_assignment_performs_assignment();
test_T_assignment_noexcept();
test_T_assignment_sfinae();
-#if !defined(_LIBCPP_ENABLE_NARROWING_CONVERSIONS_IN_VARIANT)
test_T_assignment_vector_bool();
-#endif
return 0;
}
diff --git a/libcxx/test/std/utilities/variant/variant.variant/variant.assign/conv.pass.cpp b/libcxx/test/std/utilities/variant/variant.variant/variant.assign/conv.pass.cpp
index f927db744e297c8..12913a2eee360e0 100644
--- a/libcxx/test/std/utilities/variant/variant.variant/variant.assign/conv.pass.cpp
+++ b/libcxx/test/std/utilities/variant/variant.variant/variant.assign/conv.pass.cpp
@@ -33,7 +33,7 @@ int main(int, char**)
static_assert(!std::is_assignable<std::variant<int, bool>, decltype("meow")>::value, "");
static_assert(!std::is_assignable<std::variant<int, const bool>, decltype("meow")>::value, "");
-#if defined(_LIBCPP_ENABLE_NARROWING_CONVERSIONS_IN_VARIANT)
+#ifdef _LIBCPP_ENABLE_NARROWING_CONVERSIONS_IN_VARIANT
static_assert(!std::is_assignable<std::variant<int, const volatile bool>, decltype("meow")>::value, "");
static_assert(!std::is_assignable<std::variant<bool>, std::true_type>::value, "");
#else
diff --git a/libcxx/test/std/utilities/variant/variant.variant/variant.ctor/T.pass.cpp b/libcxx/test/std/utilities/variant/variant.variant/variant.ctor/T.pass.cpp
index 4a0a31fdf320e66..e1506ef3b48ccca 100644
--- a/libcxx/test/std/utilities/variant/variant.variant/variant.ctor/T.pass.cpp
+++ b/libcxx/test/std/utilities/variant/variant.variant/variant.ctor/T.pass.cpp
@@ -80,7 +80,7 @@ void test_T_ctor_sfinae() {
};
static_assert(!std::is_constructible<V, X>::value,
"no boolean conversion in constructor");
-#if defined(_LIBCPP_ENABLE_NARROWING_CONVERSIONS_IN_VARIANT)
+#ifdef _LIBCPP_ENABLE_NARROWING_CONVERSIONS_IN_VARIANT
static_assert(!std::is_constructible<V, std::false_type>::value,
"no converted to bool in constructor");
#else
@@ -204,14 +204,14 @@ void test_construction_with_repeated_types() {
static_assert(std::is_constructible<V, Bar>::value, "");
}
-#if !defined(_LIBCPP_ENABLE_NARROWING_CONVERSIONS_IN_VARIANT)
void test_vector_bool() {
+#ifndef _LIBCPP_ENABLE_NARROWING_CONVERSIONS_IN_VARIANT
std::vector<bool> vec = {true};
std::variant<bool, int> v = vec[0];
assert(v.index() == 0);
assert(std::get<0>(v) == true);
-}
#endif
+}
int main(int, char**) {
test_T_ctor_basic();
@@ -219,8 +219,6 @@ int main(int, char**) {
test_T_ctor_sfinae();
test_no_narrowing_check_for_class_types();
test_construction_with_repeated_types();
-#if !defined(_LIBCPP_ENABLE_NARROWING_CONVERSIONS_IN_VARIANT)
test_vector_bool();
-#endif
return 0;
}
diff --git a/libcxx/test/std/utilities/variant/variant.variant/variant.ctor/conv.pass.cpp b/libcxx/test/std/utilities/variant/variant.variant/variant.ctor/conv.pass.cpp
index e4ee27a614f35d9..e03c12c4423692d 100644
--- a/libcxx/test/std/utilities/variant/variant.variant/variant.ctor/conv.pass.cpp
+++ b/libcxx/test/std/utilities/variant/variant.variant/variant.ctor/conv.pass.cpp
@@ -32,7 +32,7 @@ int main(int, char**)
static_assert(!std::is_constructible<std::variant<int, bool>, decltype("meow")>::value, "");
static_assert(!std::is_constructible<std::variant<int, const bool>, decltype("meow")>::value, "");
-#if defined(_LIBCPP_ENABLE_NARROWING_CONVERSIONS_IN_VARIANT)
+#ifdef _LIBCPP_ENABLE_NARROWING_CONVERSIONS_IN_VARIANT
static_assert(!std::is_constructible<std::variant<int, const volatile bool>, decltype("meow")>::value, "");
static_assert(!std::is_constructible<std::variant<bool>, std::true_type>::value, "");
#else
>From 26b976344aa57699302e26206fe9b3b5dc3df446 Mon Sep 17 00:00:00 2001
From: Louis Dionne <ldionne.2 at gmail.com>
Date: Wed, 22 Nov 2023 13:50:32 -0500
Subject: [PATCH 3/3] Add release note, simplify tests.
---
libcxx/docs/ReleaseNotes/18.rst | 6 ++++++
libcxx/include/variant | 1 +
.../variant/variant.variant/variant.assign/T.pass.cpp | 5 +----
.../variant/variant.variant/variant.assign/conv.pass.cpp | 7 ++-----
.../variant/variant.variant/variant.ctor/T.pass.cpp | 5 +----
.../variant/variant.variant/variant.ctor/conv.pass.cpp | 7 ++-----
libcxx/test/support/variant_test_helpers.h | 3 ++-
7 files changed, 15 insertions(+), 19 deletions(-)
diff --git a/libcxx/docs/ReleaseNotes/18.rst b/libcxx/docs/ReleaseNotes/18.rst
index c28a5b73f7ec68b..f9e0bdee3176a1a 100644
--- a/libcxx/docs/ReleaseNotes/18.rst
+++ b/libcxx/docs/ReleaseNotes/18.rst
@@ -81,6 +81,12 @@ Deprecations and Removals
- The non-conforming constructor ``std::future_error(std::error_code)`` has been removed. Please use the
``std::future_error(std::future_errc)`` constructor provided in C++17 instead.
+- `P1957 <https://wg21.link/P1957>` has been implemented in Clang and libc++ removed a code path that led to
+ narrowing conversions in ``std::variant`` behaving in a non-standard way. This may change how some uses of
+ ``std::variant``'s constructor behave in user code. The ``_LIBCPP_ENABLE_NARROWING_CONVERSIONS_IN_VARIANT``
+ macro is provided to restore the previous behavior, and it will be supported in the LLVM 18 release only.
+ In LLVM 19 and beyond, ``_LIBCPP_ENABLE_NARROWING_CONVERSIONS_IN_VARIANT`` will not be honored anymore.
+
Upcoming Deprecations and Removals
----------------------------------
diff --git a/libcxx/include/variant b/libcxx/include/variant
index 414cdc8b85469df..8f31de6da01ac6c 100644
--- a/libcxx/include/variant
+++ b/libcxx/include/variant
@@ -1252,6 +1252,7 @@ struct __overload {
auto operator()(_Tp, _Up&&) const -> __check_for_narrowing<_Tp, _Up>;
};
+// TODO(LLVM-19): Remove all occurrences of this macro.
#ifdef _LIBCPP_ENABLE_NARROWING_CONVERSIONS_IN_VARIANT
template <class _Tp, size_t>
struct __overload_bool {
diff --git a/libcxx/test/std/utilities/variant/variant.variant/variant.assign/T.pass.cpp b/libcxx/test/std/utilities/variant/variant.variant/variant.assign/T.pass.cpp
index e0782a05efcfdc5..b3fc2021a6b2237 100644
--- a/libcxx/test/std/utilities/variant/variant.variant/variant.assign/T.pass.cpp
+++ b/libcxx/test/std/utilities/variant/variant.variant/variant.assign/T.pass.cpp
@@ -146,10 +146,7 @@ void test_T_assignment_sfinae() {
};
static_assert(!std::is_assignable<V, X>::value,
"no boolean conversion in operator=");
-#ifdef _LIBCPP_ENABLE_NARROWING_CONVERSIONS_IN_VARIANT
- static_assert(!std::is_assignable<V, std::false_type>::value,
- "no converted to bool in operator=");
-#else
+#ifndef _LIBCPP_ENABLE_NARROWING_CONVERSIONS_IN_VARIANT
static_assert(std::is_assignable<V, std::false_type>::value,
"converted to bool in operator=");
#endif
diff --git a/libcxx/test/std/utilities/variant/variant.variant/variant.assign/conv.pass.cpp b/libcxx/test/std/utilities/variant/variant.variant/variant.assign/conv.pass.cpp
index 12913a2eee360e0..246309c01b4d76b 100644
--- a/libcxx/test/std/utilities/variant/variant.variant/variant.assign/conv.pass.cpp
+++ b/libcxx/test/std/utilities/variant/variant.variant/variant.assign/conv.pass.cpp
@@ -33,13 +33,10 @@ int main(int, char**)
static_assert(!std::is_assignable<std::variant<int, bool>, decltype("meow")>::value, "");
static_assert(!std::is_assignable<std::variant<int, const bool>, decltype("meow")>::value, "");
-#ifdef _LIBCPP_ENABLE_NARROWING_CONVERSIONS_IN_VARIANT
- static_assert(!std::is_assignable<std::variant<int, const volatile bool>, decltype("meow")>::value, "");
- static_assert(!std::is_assignable<std::variant<bool>, std::true_type>::value, "");
-#else
+
+#ifndef _LIBCPP_ENABLE_NARROWING_CONVERSIONS_IN_VARIANT
static_assert(std::is_assignable<std::variant<bool>, std::true_type>::value, "");
#endif
-
static_assert(!std::is_assignable<std::variant<bool>, std::unique_ptr<char> >::value, "");
static_assert(!std::is_assignable<std::variant<bool>, decltype(nullptr)>::value, "");
diff --git a/libcxx/test/std/utilities/variant/variant.variant/variant.ctor/T.pass.cpp b/libcxx/test/std/utilities/variant/variant.variant/variant.ctor/T.pass.cpp
index e1506ef3b48ccca..89fd646878eeca5 100644
--- a/libcxx/test/std/utilities/variant/variant.variant/variant.ctor/T.pass.cpp
+++ b/libcxx/test/std/utilities/variant/variant.variant/variant.ctor/T.pass.cpp
@@ -80,10 +80,7 @@ void test_T_ctor_sfinae() {
};
static_assert(!std::is_constructible<V, X>::value,
"no boolean conversion in constructor");
-#ifdef _LIBCPP_ENABLE_NARROWING_CONVERSIONS_IN_VARIANT
- static_assert(!std::is_constructible<V, std::false_type>::value,
- "no converted to bool in constructor");
-#else
+#ifndef _LIBCPP_ENABLE_NARROWING_CONVERSIONS_IN_VARIANT
static_assert(std::is_constructible<V, std::false_type>::value,
"converted to bool in constructor");
#endif
diff --git a/libcxx/test/std/utilities/variant/variant.variant/variant.ctor/conv.pass.cpp b/libcxx/test/std/utilities/variant/variant.variant/variant.ctor/conv.pass.cpp
index e03c12c4423692d..7fb44ff407653ba 100644
--- a/libcxx/test/std/utilities/variant/variant.variant/variant.ctor/conv.pass.cpp
+++ b/libcxx/test/std/utilities/variant/variant.variant/variant.ctor/conv.pass.cpp
@@ -32,13 +32,10 @@ int main(int, char**)
static_assert(!std::is_constructible<std::variant<int, bool>, decltype("meow")>::value, "");
static_assert(!std::is_constructible<std::variant<int, const bool>, decltype("meow")>::value, "");
-#ifdef _LIBCPP_ENABLE_NARROWING_CONVERSIONS_IN_VARIANT
- static_assert(!std::is_constructible<std::variant<int, const volatile bool>, decltype("meow")>::value, "");
- static_assert(!std::is_constructible<std::variant<bool>, std::true_type>::value, "");
-#else
+
+#ifndef _LIBCPP_ENABLE_NARROWING_CONVERSIONS_IN_VARIANT
static_assert(std::is_constructible<std::variant<bool>, std::true_type>::value, "");
#endif
-
static_assert(!std::is_constructible<std::variant<bool>, std::unique_ptr<char> >::value, "");
static_assert(!std::is_constructible<std::variant<bool>, decltype(nullptr)>::value, "");
diff --git a/libcxx/test/support/variant_test_helpers.h b/libcxx/test/support/variant_test_helpers.h
index 78b3978dde484bc..c174cba3284019b 100644
--- a/libcxx/test/support/variant_test_helpers.h
+++ b/libcxx/test/support/variant_test_helpers.h
@@ -23,10 +23,11 @@
// FIXME: Currently the variant<T&> tests are disabled using this macro.
#define TEST_VARIANT_HAS_NO_REFERENCES
+
+// TODO(LLVM-19): Remove TEST_VARIANT_ALLOWS_NARROWING_CONVERSIONS
#ifdef _LIBCPP_ENABLE_NARROWING_CONVERSIONS_IN_VARIANT
# define TEST_VARIANT_ALLOWS_NARROWING_CONVERSIONS
#endif
-
#ifdef TEST_VARIANT_ALLOWS_NARROWING_CONVERSIONS
constexpr bool VariantAllowsNarrowingConversions = true;
#else
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