cmd/compile/internal/types2: add test case for issue 45985

This is a port of https://golang.org/cl/317471.

Updates #45985.

Change-Id: I539d0fa6f9a77eb2fc169a21c5db9921f8eceb03
Reviewed-on: https://go-review.googlesource.com/c/go/+/317732
Trust: Robert Griesemer <gri@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>

diff --git a/src/cmd/compile/internal/types2/infer.go b/src/cmd/compile/internal/types2/infer.go
index c136823fd8ecbd646ed8ec90306b8441049e536e..f37d7f6477e96ab29bb8d0e6705cb65b0dd8cb37 100644 (file)
--- a/src/cmd/compile/internal/types2/infer.go
+++ b/src/cmd/compile/internal/types2/infer.go
@@ -417,7 +417,7 @@ func (check *Checker) inferB(tparams []*TypeName, targs []Type, report bool) (ty
        // was given, unification produced the type list [int, []C, *A]. We eliminate the
        // remaining type parameters by substituting the type parameters in this type list
        // until nothing changes anymore.
-       types, index = u.x.types()
+       types, _ = u.x.types()
        if debug {
                for i, targ := range targs {
                        assert(targ == nil || types[i] == targ)

diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue45985.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue45985.go2
new file mode 100644 (file)
index 0000000..7678e34
--- /dev/null
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue45985.go2
@@ -0,0 +1,14 @@
+// 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 issue45985
+
+// TODO(gri): this error should be on app[int] below.
+func app[S /* ERROR "type S = S does not match" */ interface{ type []T }, T any](s S, e T) S {
+    return append(s, e)
+}
+
+func _() {
+       _ = app[int]
+}