If `T` implicitly converts to `U`, then:
* `const T` implicitly converts to `U`,
* `T` implicitly converts to `const U`, and
* `T` implicitly converts to `Optional(U)`.
#6289 absentmindedly added fields in more places, and this is undoing
that plus further fixes.
This does some cleanup of types with relation to singletons. For
`TypeType` and `ErrorInst`, they're always complete due to a
`SetComplete` call in `file.cpp`. For `CppVoidType`, it's intended to be
incomplete by construction, and so a `TypeId` should be okay. The intent
though on not generally providing these had been that `GetSingletonType`
needs to be called to get a type to be marked as complete.
In the case of `AutoType`, removing `TypeId`does change a small printing
detail. I think that's old legacy that's just been carried forward.
Otherwise, for both `InstType` and `AutoType`, I've added
`GetSingletonType` calls where they were used in order to ensure
completeness is applied correctly. These calls cause small SemIR
permutations.
This causes `AutoType` to be seen by lowering, so I'm adding a
placeholder for it. Also merging two functions that look like they're
identical in intent -- not sure why they're separate.
---------
Co-authored-by: Dana Jansens <danakj@orodu.net>
This defines `Cpp.void` as a custom type.
`Cpp.void*` is mapped to C++ `void*`.
Not supported yet: Conversions from and to other pointer types.
C++ Interop Demo:
```carbon
// main.carbon
library "Main";
import Core library "io";
import Cpp inline '''
#include <cstdio>
auto GetPointer() -> void* _Nonnull {
static int x = 8;
return &x;
}
auto GetValue(void* _Nonnull ptr) -> int {
return *static_cast<int*>(ptr);
}
''';
fn Run() -> i32 {
let ptr: Cpp.void* = Cpp.GetPointer();
Core.Print(Cpp.GetValue(ptr));
return 0;
}
```
```shell
$ bazel-bin/toolchain/carbon compile main.carbon
$ bazel-bin/toolchain/carbon link main.o --output=demo
$ ./demo
8
```
Part of #6280.
Boaz Brickner
Richard Smith
Jon Ross-PerkinsandDana Jansens