cmd/compile: pop instantiations of local types when leaving scope
Since we use existing instantiations from the symbol table when possible
(to make sure each instantiation is unique), we need to pop
instantiations of local types when leaving the containing scope.
g.stmts() now pushes and pops scope, and we do a Pushdcl() in g.typ0()
when creating an instantiation of a local type.
Non-instantiated local types (generic or not) are translated directly
from types2, so they don't need to be pushed/popped. We don't export
function bodies with local types, so there is no issue during import.
We still don't support local types in generic functions/methods.
Fixes #50177
Change-Id: If2d2fe71aec003d13f0338565c7a0da2c9580a14
Reviewed-on: https://go-review.googlesource.com/c/go/+/372654 Reviewed-by: Keith Randall <khr@golang.org>
Trust: Dan Scales <danscales@google.com>
Run-TryBot: Dan Scales <danscales@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>