cmd/compile: internal compiler error: weird package in name: .dict0 => .dict0 from "", not "test/p" [1.18 backport]

[gopherbot]

@cuonglm requested issue #52117 to be considered for backport to the next 1.18 minor release.

@gopherbot please backport this to 1.18

[gopherbot]

Change https://go.dev/cl/403174 mentions this issue: [release-branch.go1.18] cmd/compile: set correct package for vars/params/results from nested instantiation

[gopherbot]

Closed by merging 1fb46d2 to release-branch.go1.18.