cmd/compile: report type loop for invalid recursive types
Similar to how we report initialization loops in initorder.go and type
alias loops in typecheck.go, this CL updates align.go to warn about
invalid recursive types. The code is based on the loop code from
initorder.go, with minimal changes to adapt from detecting
variable/function initialization loops to detecting type declaration
loops.
Thanks to Cuong Manh Le for investigating this, helping come up with
test cases, and exploring solutions.
Fixes #41575
Updates #41669.
Change-Id: Idb2cb8c5e1d645e62900e178fcb50af33e1700a1
Reviewed-on: https://go-review.googlesource.com/c/go/+/258177
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Robert Griesemer <gri@golang.org> Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Trust: Matthew Dempsky <mdempsky@google.com>
Trust: Cuong Manh Le <cuong.manhle.vn@gmail.com>