[PrintAsClang] Fix thunks for Never funcs #72402
Conversation
|
@swift-ci please test |
|
@hyp If you're still available, it sounds like you're the best person to review changes to this part of the compiler. |
| if (isResultType && Count == 0) { | ||
| // A direct result with no record members can happen for uninhabited result | ||
| // types like `Never`. | ||
| os << "void"; |
There was a problem hiding this comment.
When I was working on this PR, I noticed that IRGen represents Never return types as having one empty-tuple direct result, rather than as having no direct result. (This previously tripped an assert.) I'm assuming that this is correct, or at least that changing it would break the ABI, and that a void return with swiftcall is the correct prototype to use to call such a function from C++.
I'd love to get confirmation from someone who works on IRGen (maybe @aschwaighofer or @rjmccall?) that this is the right approach.
|
@swift-ci please test |
1 similar comment
|
@swift-ci please test |
Swift-to-C++ thunk printing for functions didn’t really take into account Swift’s `Never` type. This type maps to `SWIFT_NORETURN`, but it also requires other tweaks to code generation, such as omitting the `return` keyword. (Removing that requires minor changes to many tests.) Fixes rdar://124137073.
Extend the previous commit’s support for functions that return Never to also properly generate code for *throwing* Never functions. This is a little subtle because: • At the SWIFT_CALL level, throwing Never functions are *not* noreturn • At the thunk level, throwing Never functions are noreturn *only* if you’re using exceptions; if you’re using swift::Expected, they should throw • In either case, the compiler cannot statically prove that thunks are noreturn except on the error path, so we need to add an abort() call on the success path
`simctl spawn` does not propagate exit codes through, so we need the test to exit using `exit(0)`, not `fatalError()`.
beccadax
force-pushed
the
noreturn-for-tomorrow
branch
from
3ec1190 to
fa2ebd9
Compare
|
@swift-ci please test |
Swift-to-C++ thunk printing for functions didn’t really take into account Swift’s
Nevertype. This type maps to avoidreturn with theSWIFT_NORETURNattribute, but it also requires other tweaks to code generation, such as omitting thereturnkeyword. (Removing that requires minor changes to many tests.)This PR also contains a follow-up fix for throwing
Neverfunctions, which have a number of subtleties.Fixes rdar://124137073.