[dev.typeparams] cmd/compile: always generate (*T).M wrappers for instantiated methods

Always generate (*T).M wrappers for instantiated methods, even when the
instantiated method is being generated for another package (its source
package)

Added new function t.IsInstantiated() to check for fully-instantiated
types (generic type instantiated with concrete types, hence concrete
themselves). This function helps hide the representation of instantiated
types outside of the types package.

Added new export/import test setsimp.go that needs this change.

Change-Id: Ifb700db8c9494e1684c93735edb20f4709be5f7f
Reviewed-on: https://go-review.googlesource.com/c/go/+/322193
Trust: Dan Scales <danscales@google.com>
Trust: Robert Griesemer <gri@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>

1 files changed, 7 insertions, 0 deletions

diff --git a/src/cmd/compile/internal/types/type.go b/src/cmd/compile/internal/types/type.go
index e7831121bf..08855f518c 100644
--- a/src/cmd/compile/internal/types/type.go
+++ b/src/cmd/compile/internal/types/type.go
@@ -279,6 +279,13 @@ func (t *Type) SetRParams(rparams []*Type) {
 	}
 }
 
+// IsInstantiated reports whether t is a fully instantiated generic type; i.e. an
+// instantiated generic type where all type arguments are non-generic or fully
+// instantiated generic types.
+func (t *Type) IsInstantiated() bool {
+	return len(t.RParams()) > 0 && !t.HasTParam()
+}
+
 // NoPkg is a nil *Pkg value for clarity.
 // It's intended for use when constructing types that aren't exported
 // and thus don't need to be associated with any package.