From: Robert Griesemer <gri@golang.org>
Date: Thu, 10 Mar 2022 20:43:10 +0000 (-0800)
Subject: [release-branch.go1.18] go/types, types2: remove incorrect assertion (don't crash)
X-Git-Tag: go1.18~5
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=8706c096227ce8a7f47798699232eac453a335dd;p=gostls13.git

[release-branch.go1.18] go/types, types2: remove incorrect assertion (don't crash)

The removed assertion was never incorrect, as signatures may
be from methods in interfaces, and (some) interfaces set the
receivers of their methods (so we have a position for error
reporting).

This CL changes the issue below from a release blocker to an
issue for Go 1.19.

For #51593.

Change-Id: I0c5f2913b397b9ab557ed74a80cc7a715e840412
Reviewed-on: https://go-review.googlesource.com/c/go/+/391615
Trust: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Griesemer <gri@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
(cherry picked from commit 914195c132cbec651aa43c409e8aac2614b53b38)
Reviewed-on: https://go-review.googlesource.com/c/go/+/391796
Trust: Dmitri Shuralyov <dmitshur@golang.org>
Run-TryBot: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
---

diff --git a/src/cmd/compile/internal/types2/infer.go b/src/cmd/compile/internal/types2/infer.go
index 29633028f3..e131077371 100644
--- a/src/cmd/compile/internal/types2/infer.go
+++ b/src/cmd/compile/internal/types2/infer.go
@@ -739,8 +739,6 @@ func (w *cycleFinder) typ(typ Type) {
 	//      in signatures where they are handled explicitly.
 
 	case *Signature:
-		// There are no "method types" so we should never see a recv.
-		assert(t.recv == nil)
 		if t.params != nil {
 			w.varList(t.params.vars)
 		}
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue51593.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue51593.go2
new file mode 100644
index 0000000000..d323618ee8
--- /dev/null
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue51593.go2
@@ -0,0 +1,13 @@
+// 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
+
+func f[P interface{ m(R) }, R any]() {}
+
+type T = interface { m(int) }
+
+func _() {
+	_ = f[ /* ERROR cannot infer R */ T] // don't crash in type inference
+}
diff --git a/src/go/types/infer.go b/src/go/types/infer.go
index 429510291e..6bed55c270 100644
--- a/src/go/types/infer.go
+++ b/src/go/types/infer.go
@@ -738,8 +738,6 @@ func (w *cycleFinder) typ(typ Type) {
 	//      in signatures where they are handled explicitly.
 
 	case *Signature:
-		// There are no "method types" so we should never see a recv.
-		assert(t.recv == nil)
 		if t.params != nil {
 			w.varList(t.params.vars)
 		}
diff --git a/src/go/types/testdata/fixedbugs/issue51593.go2 b/src/go/types/testdata/fixedbugs/issue51593.go2
new file mode 100644
index 0000000000..e06c39fac0
--- /dev/null
+++ b/src/go/types/testdata/fixedbugs/issue51593.go2
@@ -0,0 +1,13 @@
+// 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
+
+func f[P interface{ m(R) }, R any]() {}
+
+type T = interface { m(int) }
+
+func _() {
+	_ = f /* ERROR cannot infer R */ [T] // don't crash in type inference
+}