cmd/compile: allow methods on shape types (but no bodies)
In a previous change, I was too aggressive in substInstType() in not
generating methods for shape types during import. We do actually want to
generate the method nodes - we just don't want to generate method bodies
(which we would never use). We may need the method nodes for checking
types later in the compile (especially with inlining).
So, we do generate method nodes for shape types during import. In
order to avoid the name collision we previously had, we now add
".nofunc." to the method nodes for shape types (during import and in the
type substituter). We do that by passing in a 'isMethodNode' arg to
MakeInstSym. We keep the normal name (without ".nofunc") for any other
method nodes, and for the instantiated functions that help with
implementing the methods of fully-instantiated types. The ".nofunc"
names will never appear in the executable, since we don't generate any
method bodies for the method nodes of shape types.
Change-Id: I3e57e328691214140ca5f48d32011552d2a0d45d
Reviewed-on: https://go-review.googlesource.com/c/go/+/352470
Trust: Dan Scales <danscales@google.com> Reviewed-by: Keith Randall <khr@golang.org>