[dev.typeparams] cmd/compile/internal/types2: expand is only required for *Named types

Now that the pointer identity for a *Named type doesn't change
anymore when going from lazy instantiated to actually instantiated
(= expanded) state, expand() only needs to be called when we deal
with *Named types and only if we care about a *Named type's internals.

Remove the expand function and respective calls for all types and
replace with specific t.expand() method calls where t is a *Named.

Change-Id: If82299360d60108b00adc4013b29399aec90b940
Reviewed-on: https://go-review.googlesource.com/c/go/+/340749
Trust: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Griesemer <gri@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>

1 files changed, 0 insertions, 9 deletions

diff --git a/src/cmd/compile/internal/types2/named.go b/src/cmd/compile/internal/types2/named.go
index 14e073bfae..e099660481 100644
--- a/src/cmd/compile/internal/types2/named.go
+++ b/src/cmd/compile/internal/types2/named.go
@@ -279,12 +279,3 @@ func (n *Named) expand() {
 		n.instance = nil
 	}
 }
-
-// expand expands uninstantiated named types and leaves all other types alone.
-// expand does not recurse.
-func expand(typ Type) Type {
-	if t, _ := typ.(*Named); t != nil {
-		t.expand()
-	}
-	return typ
-}