Due to a now default-enabled `undef` pass (llvm/llvm-project
1b1c8d83d3567a60280291c0adb95d1d60335509), a whole bunch of interop
IRGen tests are failing due to missing `undefs`, even though they don't
matter in these tests at all. Add regex matches so that these tests just
check for the name and types of the functions they care about.
Clang will properly mark the C++ `this` parameter as `nonnull` and
`dereferenceable(1)` as per the C++ specification. Update the tests to
accept the newer attributes.
Currently the following code doesn't work when `callConstructor()` is called from Swift:
```cc
inline int increment(int value) {
return value + 1;
}
struct Incrementor {
int incrementee;
Incrementor(int value) : incrementee(increment(value)) {}
}
int callConstructor(int value) {
return Incrementor(value).incrementee;
}
```
The issue is that we don't generate `IR` for the `increment()` function when it's only called from a constructor or a method.
Swift is aware of the existence of `increment()` and we see it in `IR` as `declare incrementEi`, however, as we don't to emit a definition, we get the following error:
```
Incrementor::Incrementor(int): error: undefined reference to 'increment(int)'
```
This PR fixes this by visiting constructors and methods in `IRGen` and calling `HandleTopLevelDecl()` with all used declarations, which results in emitting definitions for the used declarations.
Co-authored-by: Marcel Hlopko <hlopko@google.com>
