From cef8f5c6a47abfc571a04ddfd00e8b7822e19a7a Mon Sep 17 00:00:00 2001
From: Robert Griesemer <gri@golang.org>
Date: Wed, 18 Dec 2019 11:01:59 -0800
Subject: [PATCH] go/types: move includeTypes function to a method of Interface
 (cleanup)

Change-Id: Ic3a4beaa279b6d6349136f5a9ff0447227cabb5a
---
 src/go/types/subst.go | 15 ++-------------
 src/go/types/type.go  | 10 ++++++++++
 2 files changed, 12 insertions(+), 13 deletions(-)

diff --git a/src/go/types/subst.go b/src/go/types/subst.go
index 5b03a23251..fe28931caa 100644
--- a/src/go/types/subst.go
+++ b/src/go/types/subst.go
@@ -104,7 +104,7 @@ func (check *Checker) instantiate(pos token.Pos, typ Type, targs []Type, poslist
 		// list of iface types (i.e., the targ type list must be a subset of the iface types)
 		if targ, _ := targ.Underlying().(*TypeParam); targ != nil {
 			for _, t := range targ.Interface().types {
-				if !includesType(t, iface) {
+				if !iface.includes(t.Underlying()) {
 					// TODO(gri) match this error message with the one below (or vice versa)
 					check.softErrorf(pos, "%s does not satisfy %s (missing type %s)", targ, tpar.bound, t)
 					break
@@ -116,7 +116,7 @@ func (check *Checker) instantiate(pos token.Pos, typ Type, targs []Type, poslist
 		// otherwise, targ's underlying type must also be one of the interface types listed, if any
 		if len(iface.types) > 0 {
 			// TODO(gri) must it be the underlying type, or should it just be the type? (spec question)
-			if !includesType(targ.Underlying(), iface) {
+			if !iface.includes(targ.Underlying()) {
 				check.softErrorf(pos, "%s does not satisfy %s (%s not found in %s)", targ, tpar.bound, targ, iface)
 				break
 			}
@@ -126,17 +126,6 @@ func (check *Checker) instantiate(pos token.Pos, typ Type, targs []Type, poslist
 	return check.subst(pos, typ, tparams, targs)
 }
 
-// includesType reports whether iface includes typ
-// TODO(gri) make this a method of *Interface
-func includesType(typ Type, iface *Interface) bool {
-	for _, t := range iface.types {
-		if Identical(typ.Underlying(), t) {
-			return true
-		}
-	}
-	return false
-}
-
 // subst returns the type typ with its type parameters tparams replaced by
 // the corresponding type arguments targs, recursively.
 func (check *Checker) subst(pos token.Pos, typ Type, tpars []*TypeName, targs []Type) Type {
diff --git a/src/go/types/type.go b/src/go/types/type.go
index 2105b52b09..19fde623a0 100644
--- a/src/go/types/type.go
+++ b/src/go/types/type.go
@@ -362,6 +362,16 @@ func (t *Interface) Method(i int) *Func { t.assertCompleteness(); return t.allMe
 // The interface must have been completed.
 func (t *Interface) Empty() bool { t.assertCompleteness(); return len(t.allMethods) == 0 }
 
+// includes reports whether the interface t includes the type typ.
+func (t *Interface) includes(typ Type) bool {
+	for _, t := range t.types {
+		if Identical(t, typ) {
+			return true
+		}
+	}
+	return false
+}
+
 // Complete computes the interface's method 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