[SR-15667] [AutoDiff] Providing exact type for generic parameter in @differentiable can lead to an assertion failure #57946
Comments
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I have narrowed down the regression further. Perhaps the differentiable function being called here is import _Differentiation
// `Root` can be constrained to `Differentiable` here, rather than in the
// extension. The crash happens either way.
struct TestKeyPaths<Root, Value>{}
// Adding `where Value == Int` causes the crash. Either removing that or
// substituting with `where Value: Differentiable` eliminates the crash.
extension TestKeyPaths where Root: Differentiable, Value == Int {
@differentiable(reverse)
static func readAll(from root: Root) -> Double {
// Removing the force-unwrap eliminates the crash.
let ignored = Root?(nil)!
return 0
}
}Build output |
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Additional Detail from JIRA
md5: 30987d0cfba9255fa519471be9e3d5bd
Issue Description:
When a differentiable function refines a generic parameter to a specific type, but a differentiable function called within that function isn't as refined, it can sometimes lead to an assertion failure of "(OrigType == signature.getCanonicalTypeInContext(origType)), function initSwiftType, file AbstractionPattern.h, line 533".
The following single-file reproducer triggers this:
To observe the assertion failure, place the above in a file and build via `swiftc file.swift`. The assertion failure goes away if the line
@differentiable(reverse where Root: Differentiable, Value == Float)is replaced with
@differentiable(reverse where Root: Differentiable, Value: Differentiable)This appears to not be a recent regression, and is present in current nightly toolchain snapshots. The full text of the assertion failure is as follows:
The text was updated successfully, but these errors were encountered: