From: Cherry Mui <cherryyz@google.com>
Date: Wed, 15 Dec 2021 17:34:34 +0000 (-0500)
Subject: cmd/compile: correct type identity comparison with "any"
X-Git-Tag: go1.18beta2~231
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=bc0aba971705722b6798746b2003908166ee007b;p=gostls13.git

cmd/compile: correct type identity comparison with "any"

The builtin "any" type should only be identical to an unnamed empty
interface type, not a defined empty interface type.

Fixes #50169.

Change-Id: Ie5bb88868497cb795de1fd0276133ba9812edfe4
Reviewed-on: https://go-review.googlesource.com/c/go/+/372217
Trust: Cherry Mui <cherryyz@google.com>
Trust: Dan Scales <danscales@google.com>
Reviewed-by: Dan Scales <danscales@google.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: Cherry Mui <cherryyz@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
---

diff --git a/src/cmd/compile/internal/types/identity.go b/src/cmd/compile/internal/types/identity.go
index a164b84da9..60a0f2e7c5 100644
--- a/src/cmd/compile/internal/types/identity.go
+++ b/src/cmd/compile/internal/types/identity.go
@@ -59,12 +59,13 @@ func identical(t1, t2 *Type, flags int, assumedEqual map[typePair]struct{}) bool
 		case TINT32:
 			return (t1 == Types[TINT32] || t1 == RuneType) && (t2 == Types[TINT32] || t2 == RuneType)
 		case TINTER:
-			// Make sure named any type matches any empty interface
+			// Make sure named any type matches any unnamed empty interface
 			// (but not a shape type, if identStrict).
+			isUnnamedEface := func(t *Type) bool { return t.IsEmptyInterface() && t.Sym() == nil }
 			if flags&identStrict != 0 {
-				return t1 == AnyType && t2.IsEmptyInterface() && !t2.HasShape() || t2 == AnyType && t1.IsEmptyInterface() && !t1.HasShape()
+				return t1 == AnyType && isUnnamedEface(t2) && !t2.HasShape() || t2 == AnyType && isUnnamedEface(t1) && !t1.HasShape()
 			}
-			return t1 == AnyType && t2.IsEmptyInterface() || t2 == AnyType && t1.IsEmptyInterface()
+			return t1 == AnyType && isUnnamedEface(t2) || t2 == AnyType && isUnnamedEface(t1)
 		default:
 			return false
 		}
diff --git a/test/fixedbugs/issue50169.go b/test/fixedbugs/issue50169.go
new file mode 100644
index 0000000000..30d2713ec9
--- /dev/null
+++ b/test/fixedbugs/issue50169.go
@@ -0,0 +1,24 @@
+// compile
+
+// Copyright 2021 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 main
+
+func main() {
+	var x Value
+	NewScanner().Scan(x)
+}
+
+type Value any
+
+type Scanner interface{ Scan(any) error }
+
+func NewScanner() Scanner {
+	return &t{}
+}
+
+type t struct{}
+
+func (*t) Scan(interface{}) error { return nil }