| Issue |
81774
|
| Summary |
Clang incorrectly rejects default construction of union with nontrivial member, part 2
|
| Labels |
clang
|
| Assignees |
|
| Reporter |
StephanTLavavej
|
Accepted by VS 2022 17.10 Preview 1, rejected by Clang 17.0.3.
On Compiler Explorer, accepted by GCC 13.2, rejected by Clang 17.0.1 and trunk: https://godbolt.org/z/8fGhWa1ss
Presumably related to #48416 which was previously reported and fixed, but this larger repro is still failing.
```
C:\Temp>type meow.cpp
```
```cpp
enum class BasicFormatArgType { NoType, CustomType };
struct Monostate {};
struct Handle {
Handle(int, int) {}
};
template <typename Context>
struct BasicFormatArg {
BasicFormatArg() = default;
BasicFormatArg(int x, int y) : ActiveState(BasicFormatArgType::CustomType), CustomState(x, y) {}
BasicFormatArgType ActiveState = BasicFormatArgType::NoType;
union {
Monostate NoState = Monostate{};
Handle CustomState;
};
};
int main() {
BasicFormatArg<double> arg{};
(void) arg;
}
```
```
C:\Temp>cl /EHsc /nologo /W4 /std:c++latest /c meow.cpp
meow.cpp
C:\Temp>clang-cl -v
clang version 17.0.3
Target: x86_64-pc-windows-msvc
Thread model: posix
InstalledDir: C:\Program Files\Microsoft Visual Studio\2022\Preview\VC\Tools\Llvm\x64\bin
C:\Temp>clang-cl /EHsc /nologo /W4 /std:c++latest /c meow.cpp
meow.cpp(24,28): error: call to implicitly-deleted default constructor of 'BasicFormatArg<double>'
24 | BasicFormatArg<double> arg{};
| ^ ~~
meow.cpp(11,5): note: explicitly defaulted function was implicitly deleted here
11 | BasicFormatArg() = default;
| ^
meow.cpp(19,16): note: default constructor of 'BasicFormatArg<double>' is implicitly deleted because field 'CustomState'
has no default constructor
19 | Handle CustomState;
| ^
1 error generated.
```
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