================
@@ -24,6 +44,103 @@ using enum E;
#endif
}
+namespace cwg2627 { // cwg2627: 19
+#if __cplusplus >= 202002L
+struct C {
+ long long i : 8;
+ friend auto operator<=>(C, C) = default;
+};
+
+void f() {
+ C x{1}, y{2};
+ static_cast<void>(x <=> y);
+ static_cast<void>(x.i <=> y.i);
+}
+
+template<typename T>
+struct CDependent {
+ T i : 8;
+ friend auto operator<=>(CDependent, CDependent) = default;
+};
+
+template<typename T>
+concept three_way_comparable = requires(T t) { { t <=> t }; };
+template<typename T>
+concept bf_three_way_comparable = requires(T t) { { t.i <=> t.i }; };
+static_assert(three_way_comparable<CDependent<long long>>);
+static_assert(bf_three_way_comparable<CDependent<long long>>);
+#endif
+
+#if __cplusplus >= 201103L
+template<int W>
+struct D {
+ __int128 i : W;
+};
+
+template<int W>
+std::int64_t f(D<W> d) {
+ return std::int64_t{ d.i }; // #cwg2627-f
+}
+
+template std::int64_t f(D<63>);
+template std::int64_t f(D<64>);
+template std::int64_t f(D<65>);
+// since-cxx11-error-re@#cwg2627-f {{non-constant-expression cannot be
narrowed from type '__int128' to 'std::int64_t' (aka '{{.+}}') in initializer
list}}
+// since-cxx11-note@-2 {{in instantiation of function template
specialization 'cwg2627::f<65>' requested here}}
+// since-cxx11-note@#cwg2627-f {{insert an explicit cast to silence this
issue}}
+
+template<typename Target, typename Source>
+Target g(Source x) {
+ return Target{ x.i }; // #cwg2627-g
+}
+
+template<typename T, int N>
+struct E {
+ T i : N;
+};
+
+template std::int16_t g(E<int, 16>);
+template std::int16_t g(E<unsigned, 15>);
+template std::int16_t g(E<unsigned, 16>);
+// since-cxx11-error-re@#cwg2627-g {{non-constant-expression cannot be
narrowed from type 'unsigned int' to '{{.+}}' in initializer list}}
+// since-cxx11-note-re@-2 {{in instantiation of function template
specialization 'cwg2627::g<{{.+}}, cwg2627::E<unsigned int, 16>>' requested
here}}
+// since-cxx11-note@#cwg2627-g {{insert an explicit cast to silence this
issue}}
+template std::uint16_t g(E<unsigned, 16>);
+template std::uint16_t g(E<int, 1>);
+// since-cxx11-error-re@#cwg2627-g {{non-constant-expression cannot be
narrowed from type 'int' to '{{.+}}' in initializer list}}
+// since-cxx11-note-re@-2 {{in instantiation of function template
specialization 'cwg2627::g<{{.+}}, cwg2627::E<int, 1>>' requested here}}
+// since-cxx11-note@#cwg2627-g {{insert an explicit cast to silence this
issue}}
+
+template bool g(E<unsigned, 1>);
+template bool g(E<int, 1>);
+// since-cxx11-error@#cwg2627-g {{non-constant-expression cannot be narrowed
from type 'int' to 'bool' in initializer list}}
+// since-cxx11-note@-2 {{in instantiation of function template
specialization 'cwg2627::g<bool, cwg2627::E<int, 1>>' requested here}}
+// since-cxx11-note@#cwg2627-g {{insert an explicit cast to silence this
issue}}
+
+template<typename Target, typename Source>
+constexpr decltype(Target{ std::declval<Source>().i }, false)
is_narrowing(int) { return false; }
+template<typename Target, typename Source>
+constexpr bool is_narrowing(long) { return true; }
+
+static_assert(!is_narrowing<std::int16_t, E<int, 16>>(0), "");
+static_assert(!is_narrowing<std::int16_t, E<unsigned, 15>>(0), "");
+static_assert(is_narrowing<std::int16_t, E<unsigned, 16>>(0), "");
+static_assert(!is_narrowing<std::uint16_t, E<unsigned, 16>>(0), "");
+static_assert(is_narrowing<std::uint16_t, E<int, 1>>(0), "");
+static_assert(!is_narrowing<bool, E<unsigned, 1>>(0), "");
+static_assert(is_narrowing<bool, E<int, 1>>(0), "");
+
+template<int N>
+struct F {
+ signed int x : N;
+ decltype(std::int16_t{ x }) dependent_narrowing;
+ decltype(unsigned{ x }) always_narrowing;
+// since-cxx11-error@-1 {{non-constant-expression cannot be narrowed from type
'int' to 'unsigned int' in initializer list}}
+// since-cxx11-note@-2 {{insert an explicit cast to silence this issue}}
+};
+#endif
+}
----------------
Endilll wrote:
```suggestion
} // namespace cwg2627
```
https://github.com/llvm/llvm-project/pull/78112
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