[release-branch.go1.18] cmd/compile: fix missing dict pass for type assertions

For type assertions, if either src or dst type has shape, we must
convert them to dynamic type assertions.

Fixes #53357

Change-Id: Ia3362fa67c011febcbdb5b26f856d081b5c366de
Reviewed-on: https://go-review.googlesource.com/c/go/+/411617
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-on: https://go-review.googlesource.com/c/go/+/411934
Reviewed-by: Keith Randall <khr@google.com>

2 files changed, 44 insertions, 2 deletions

diff --git a/src/cmd/compile/internal/noder/stencil.go b/src/cmd/compile/internal/noder/stencil.go
index 58b7b9e8ddf..7cfd70ec546 100644
--- a/src/cmd/compile/internal/noder/stencil.go
+++ b/src/cmd/compile/internal/noder/stencil.go
@@ -1297,10 +1297,10 @@ func (g *genInst) dictPass(info *instInfo) {
 				m = convertUsingDictionary(info, info.dictParam, m.Pos(), mce.X, m, m.Type(), false)
 			}
 		case ir.ODOTTYPE, ir.ODOTTYPE2:
-			if !m.Type().HasShape() {
+			dt := m.(*ir.TypeAssertExpr)
+			if !dt.Type().HasShape() && !dt.X.Type().HasShape() {
 				break
 			}
-			dt := m.(*ir.TypeAssertExpr)
 			var rt ir.Node
 			if dt.Type().IsInterface() || dt.X.Type().IsEmptyInterface() {
 				ix := findDictType(info, m.Type())
diff --git a/test/typeparam/issue53309.go b/test/typeparam/issue53309.go
new file mode 100644
index 00000000000..d505f6b58a6
--- /dev/null
+++ b/test/typeparam/issue53309.go
@@ -0,0 +1,42 @@
+// run -gcflags=-G=3
+
+// 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 main
+
+type TaskInput interface {
+	deps() []*taskDefinition
+}
+
+type Value[T any] interface {
+	metaValue
+}
+
+type metaValue interface {
+	TaskInput
+}
+
+type taskDefinition struct {
+}
+
+type taskResult struct {
+	task *taskDefinition
+}
+
+func (tr *taskResult) deps() []*taskDefinition {
+	return nil
+}
+
+func use[T any](v Value[T]) {
+	_, ok := v.(*taskResult)
+	if !ok {
+		panic("output must be *taskResult")
+	}
+}
+
+func main() {
+	tr := &taskResult{&taskDefinition{}}
+	use(Value[string](tr))
+}