go/types, types2: disable inference for type instances

Inference for type instances has dependencies on type-checking order
that can lead to subtle bugs. As explained in #51527, disable it for
1.18.

Fixes #51527

Change-Id: I42795bad30ce53abecfc5a4914599ae5a2041a9e
Reviewed-on: https://go-review.googlesource.com/c/go/+/387934
Trust: Robert Findley <rfindley@google.com>
Run-TryBot: Robert Findley <rfindley@google.com>
Reviewed-by: Robert Griesemer <gri@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>

2 files changed, 17 insertions, 11 deletions

diff --git a/test/typeparam/issue51232.go b/test/typeparam/issue51232.go
index 44d114d235..0d25e1863d 100644
--- a/test/typeparam/issue51232.go
+++ b/test/typeparam/issue51232.go
@@ -1,4 +1,4 @@
-// compile
+// errorcheck
 
 // Copyright 2022 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
@@ -13,19 +13,19 @@ type RC[RG any] interface {
 type Fn[RCT RC[RG], RG any] func(RCT)
 
 type F[RCT RC[RG], RG any] interface {
-	Fn() Fn[RCT]
+	Fn() Fn[RCT] // ERROR "got 1 arguments"
 }
 
 type concreteF[RCT RC[RG], RG any] struct {
-	makeFn func() Fn[RCT]
+	makeFn func() Fn[RCT] // ERROR "got 1 arguments"
 }
 
-func (c *concreteF[RCT, RG]) Fn() Fn[RCT] {
+func (c *concreteF[RCT, RG]) Fn() Fn[RCT] { // ERROR "got 1 arguments"
 	return c.makeFn()
 }
 
-func NewConcrete[RCT RC[RG], RG any](Rc RCT) F[RCT] {
-	return &concreteF[RCT]{
+func NewConcrete[RCT RC[RG], RG any](Rc RCT) F[RCT] { // ERROR "got 1 arguments"
+	return &concreteF[RCT]{ // ERROR "cannot use" "got 1 arguments"
 		makeFn: nil,
 	}
 }
diff --git a/test/typeparam/issue51233.go b/test/typeparam/issue51233.go
index 9411f2e6b5..96a25ddb9c 100644
--- a/test/typeparam/issue51233.go
+++ b/test/typeparam/issue51233.go
@@ -1,22 +1,28 @@
-// compile
+// errorcheck
 
 // Copyright 2022 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 package p
 
+// As of issue #51527, type-type inference has been disabled.
+
 type RC[RG any] interface {
 	~[]RG
 }
+
 type Fn[RCT RC[RG], RG any] func(RCT)
-type FFn[RCT RC[RG], RG any] func() Fn[RCT]
+
+type FFn[RCT RC[RG], RG any] func() Fn[RCT] // ERROR "got 1 arguments"
+
 type F[RCT RC[RG], RG any] interface {
-	Fn() Fn[RCT]
+	Fn() Fn[RCT] // ERROR "got 1 arguments"
 }
+
 type concreteF[RCT RC[RG], RG any] struct {
-	makeFn FFn[RCT]
+	makeFn FFn[RCT] // ERROR "got 1 arguments"
 }
 
-func (c *concreteF[RCT, RG]) Fn() Fn[RCT] {
+func (c *concreteF[RCT, RG]) Fn() Fn[RCT] { // ERROR "got 1 arguments"
 	return c.makeFn()
 }