This is phase-1 of switching from llvm::Optional to std::optional in the
next rebranch. llvm::Optional was removed from upstream LLVM, so we need
to migrate off rather soon. On Darwin, std::optional, and llvm::Optional
have the same layout, so we don't need to be as concerned about ABI
beyond the name mangling. `llvm::Optional` is only returned from one
function in
```
getStandardTypeSubst(StringRef TypeName,
bool allowConcurrencyManglings);
```
It's the return value, so it should not impact the mangling of the
function, and the layout is the same as `std::optional`, so it should be
mostly okay. This function doesn't appear to have users, and the ABI was
already broken 2 years ago for concurrency and no one seemed to notice
so this should be "okay".
I'm doing the migration incrementally so that folks working on main can
cherry-pick back to the release/5.9 branch. Once 5.9 is done and locked
away, then we can go through and finish the replacement. Since `None`
and `Optional` show up in contexts where they are not `llvm::None` and
`llvm::Optional`, I'm preparing the work now by going through and
removing the namespace unwrapping and making the `llvm` namespace
explicit. This should make it fairly mechanical to go through and
replace llvm::Optional with std::optional, and llvm::None with
std::nullopt. It's also a change that can be brought onto the
release/5.9 with minimal impact. This should be an NFC change.
Whe completing in parameter packs, we were calling `getParameterAt` with `Res.FuncDeclRef`. But the substitution map in `Res.FuncDeclRef` contained type variables that were allocated in the constraint system’s arena. And that arena had been freed when we call this from `deliverResults`.
The fix is to compute the optional parameters in advance in `sawSolutionImpl`
rdar://109093909
We previously asserted that for a call the function type had the same number of parameters as the declaration. But that’s not true for parameter packs anymore because the parameter pack will be exploded in the function type to account for passing multiple arguments to the pack.
To fix this, use `ConcreteDeclRef` instead of a `ValueDecl`, which has a substitution map and is able to account for the exploded parameter packs when accessed using `getParameterAt`.
rdar://100066716
This eliminates a source of bugs if subclasses of `TypeCheckCompletionCallback` forget to call the superclass’s implementation of `sawSolution` from their overridden method.
This hooks up call argument position completion to the typeCheckForCodeCompletion API to generate completions from all the solutions the constraint solver produces (even those requiring fixes), rather than relying on a single solution being applied to the AST (if any).
Co-authored-by: Nathan Hawes <nathan.john.hawes@gmail.com>
