[dev.typeparams] cmd/compile/internal/types2: remove Interface.Complete (cleanup)

Interface.Complete is not needed anymore. We can remove it in
types2 (and eventually make it an empty function in go/types,
where we must maintain the existing API).

Change-Id: I689f0d6f3a83997d8ca5bae773b9af0083d0bf4f
Reviewed-on: https://go-review.googlesource.com/c/go/+/340255
Trust: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>

src/cmd/compile/internal/importer/iimport.go

@@ -183,10 +183,6 @@ func ImportData(imports map[string]*types2.Package, data, path string) (pkg *typ
 		p.doDecl(localpkg, name)
 	}
 
-	for _, typ := range p.interfaceList {
-		typ.Complete()
-	}
-
 	// record all referenced packages as imports
 	list := append(([]*types2.Package)(nil), pkgList[1:]...)
 	sort.Sort(byPath(list))

src/cmd/compile/internal/noder/reader2.go

@@ -303,9 +303,7 @@ func (r *reader2) interfaceType() *types2.Interface {
 		embeddeds[i] = r.typ()
 	}
 
-	typ := types2.NewInterfaceType(methods, embeddeds)
-	typ.Complete()
-	return typ
+	return types2.NewInterfaceType(methods, embeddeds)
 }
 
 func (r *reader2) signature(recv *types2.Var) *types2.Signature {

src/cmd/compile/internal/types2/interface.go

@@ -100,25 +100,6 @@ func (t *Interface) IsComparable() bool { return t.typeSet().IsComparable() }
 // IsConstraint reports whether interface t is not just a method set.
 func (t *Interface) IsConstraint() bool { return !t.typeSet().IsMethodSet() }
 
-// Complete computes the interface's type set. It must be called by users of
-// NewInterfaceType and NewInterface after the interface's embedded types are
-// fully defined and before using the interface type in any way other than to
-// form other types. The interface must not contain duplicate methods or a
-// panic occurs. Complete returns the receiver.
-//
-// Deprecated: Type sets are now computed lazily, on demand; this function
-//             is only here for backward-compatibility. It does not have to
-//             be called explicitly anymore.
-func (t *Interface) Complete() *Interface {
-	// Some tests are still depending on the state change
-	// (string representation of an Interface not containing an
-	// /* incomplete */ marker) caused by the explicit Complete
-	// call, so we compute the type set eagerly here.
-	t.complete = true
-	t.typeSet()
-	return t
-}
-
 func (t *Interface) Underlying() Type { return t }
 func (t *Interface) String() string   { return TypeString(t, nil) }
 

src/cmd/compile/internal/types2/issues_test.go

@@ -402,8 +402,9 @@ func TestIssue28282(t *testing.T) {
 	// create type interface { error }
 	et := Universe.Lookup("error").Type()
 	it := NewInterfaceType(nil, []Type{et})
-	it.Complete()
 	// verify that after completing the interface, the embedded method remains unchanged
+	// (interfaces are "completed" lazily now, so the completion happens implicitly when
+	// accessing Method(0))
 	want := et.Underlying().(*Interface).Method(0)
 	got := it.Method(0)
 	if got != want {