Consider the case of a toolchain that includes clang is being used to
compile Swift. With the current ordering, the header will be found
relative to that toolchain, which could be out of date as compared to
tip. This is the case today if eg. a 5.7 toolchain is used to build
main/5.9 as the shim header is missing a definition.
Reformatting everything now that we have `llvm` namespaces. I've
separated this from the main commit to help manage merge-conflicts and
for making it a bit easier to read the mega-patch.
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.
[interop][SwiftToCxx] avoid emitting ambiguous C++ overloads and emit unavailable type stubs for top level types that could not be emitted in the C++ section of the generated header
The only state `getSwiftName` uses is its argument, and can be made a free function. Of
note the inverse operation, `getKnownFoundationEntity`, is also a free function. This
removes the requirement that callers have an `ASTContext` instance.
(cherry-picked from commit fb524c0b86)
If the C++ compiler doesn't support the transparent_stepping attribute,
fallback to annotating inline thunks with the alwaysinline and nodebug
attributes.
Use transparent_stepping instead of nodebug and alwaysinline in compiler
generated C++ code from Swift. This attribute allow for annotated
functions to be used in expression evaluation, which is an advantage
over the former two.
The frontend option '-clang-header-expose-module' allows the user to specify that APIs from an imported module have been exposed in another generated header, and thus APIs that depend on them can be safely exposed in the current generated header.
A lot of the fixes here are adjustments to compensate in the
fulfillment and metadata-path subsystems for the recent pack
substitutions representation change. I think these adjustments
really make the case for why the change was the right one to make:
the code was clearly not considering the possibility of packs
in these positions, and the need to handle packs makes everything
work out much more cleanly.
There's still some work that needs to happen around type packs;
in particular, we're not caching them or fulfilling them as a
whole, and we do have the setup to do that properly now.
