go/types: no way to construct the signature of append(s, "string"...) via the API [1.19 backport]

[gopherbot]

@findleyr requested issue #55030 to be considered for backport to the next 1.19 minor release.

@gopherbot please consider this for backport to 1.18 and 1.19, it is a bug that NewSignatureType panics on valid signatures.

[gopherbot]

Change https://go.dev/cl/431935 mentions this issue: [release-branch.go1.19] go/types, types2: allow (string...) signature with NewSignatureType

[gopherbot]

Closed by merging a366ed5 to release-branch.go1.19.