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>

diff --git a/src/cmd/compile/internal/types2/infer.go b/src/cmd/compile/internal/types2/infer.go
index 29633028f35f902f0703feb409e41aaba2501cfe..e131077371601ed1468b9270377031e4438452c2 100644 (file)
--- 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 (file)
index 0000000..d323618
--- /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 429510291ed728e2eceeaf00ada203464b350c34..6bed55c270f46b15359001437004266db2ec074c 100644 (file)
--- 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 (file)
index 0000000..e06c39f
--- /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
+}