cmd/compile: spurious not a slice error when calling unsafe.SliceData on a type-parameterized slice #64406
Description
Go version
Go 1.21 (playground)
What operating system and processor architecture are you using (go env)?
playgroundWhat did you do?
https://go.dev/play/p/1onZLUkD_VX
What did you expect to see?
successful compilation
What did you see instead?
./prog.go:8:26: invalid argument: s (variable of type S constrained by ~[]E) is not a slice
But it clearly is a slice, because (according to the same error message) it is constrained by ~[]E.
(attn @griesemer)