cmd/compile: fix unified IR shapifying recursive instantiated types
Shape-based stenciling in unified IR is done by converting type argument
to its underlying type. So it agressively check that type argument is
not a TFORW. However, for recursive instantiated type argument, it may
still be a TFORW when shapifying happens. Thus the assertion failed,
causing the compiler crashing.
To fix it, just allow fully instantiated type when shapifying.
Fixes #54512
Fixes #54722
Change-Id: I527e3fd696388c8a37454e738f0324f0c2ec16cb
Reviewed-on: https://go-review.googlesource.com/c/go/+/426335
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com> Reviewed-by: Heschi Kreinick <heschi@google.com> Reviewed-by: Matthew Dempsky <mdempsky@google.com>