test: additional generic type switch test coverage

None of the current generic type switch test cases exercise type
switches where the instantiated case is an interface type.

Change-Id: I9272fa61b8dde1fe1a3702d524d4f40253ef19b2
Reviewed-on: https://go-review.googlesource.com/c/go/+/390354
Trust: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>

test/typeparam/typeswitch1.go

@@ -28,4 +28,6 @@ func main() {
 	f[float64](int8(9))
 	f[int32](int32(7))
 	f[int](int32(7))
+	f[any](int(10))
+	f[interface{ M() }](int(11))
 }

test/typeparam/typeswitch1.out

@@ -5,3 +5,5 @@ struct{T,T}
 other
 T
 int32/int16
+T
+int

test/typeparam/typeswitch2.go

@@ -6,20 +6,20 @@
 
 package main
 
-import "reflect"
+import "fmt"
 
 func f[T any](i interface{}) {
 	switch x := i.(type) {
 	case T:
-		println("T", x)
+		fmt.Println("T", x)
 	case int:
-		println("int", x)
+		fmt.Println("int", x)
 	case int32, int16:
-		println("int32/int16", reflect.ValueOf(x).Int())
+		fmt.Println("int32/int16", x)
 	case struct{ a, b T }:
-		println("struct{T,T}", x.a, x.b)
+		fmt.Println("struct{T,T}", x.a, x.b)
 	default:
-		println("other", reflect.ValueOf(x).Int())
+		fmt.Println("other", x)
 	}
 }
 func main() {
@@ -30,4 +30,6 @@ func main() {
 	f[float64](int8(9))
 	f[int32](int32(7))
 	f[int](int32(7))
+	f[any](int(10))
+	f[interface{ M() }](int(11))
 }

test/typeparam/typeswitch2.out

@@ -1,7 +1,9 @@
-T +6.000000e+000
+T 6
 int 7
 int32/int16 8
-struct{T,T} +1.000000e+000 +2.000000e+000
+struct{T,T} 1 2
 other 9
 T 7
 int32/int16 7
+T 10
+int 11

test/typeparam/typeswitch3.go

@@ -7,6 +7,10 @@
 package main
 
 type I interface{ foo() int }
+type J interface {
+	I
+	bar()
+}
 
 type myint int
 
@@ -19,6 +23,7 @@ func (x myfloat) foo() int { return int(x) }
 type myint32 int32
 
 func (x myint32) foo() int { return int(x) }
+func (x myint32) bar()     {}
 
 func f[T I](i I) {
 	switch x := i.(type) {
@@ -37,4 +42,7 @@ func main() {
 	f[myint32](myint32(8))
 	f[myint32](myfloat(7))
 	f[myint](myint32(9))
+	f[I](myint(10))
+	f[J](myint(11))
+	f[J](myint32(12))
 }

test/typeparam/typeswitch3.out

@@ -4,3 +4,6 @@ other 8
 T 8
 other 7
 other 9
+T 10
+myint 11
+T 12

test/typeparam/typeswitch4.go

@@ -7,6 +7,10 @@
 package main
 
 type I interface{ foo() int }
+type J interface {
+	I
+	bar()
+}
 
 type myint int
 
@@ -19,6 +23,7 @@ func (x myfloat) foo() int { return int(x) }
 type myint32 int32
 
 func (x myint32) foo() int { return int(x) }
+func (x myint32) bar()     {}
 
 func f[T I](i I) {
 	switch x := i.(type) {
@@ -35,4 +40,7 @@ func main() {
 	f[myint32](myint32(9))
 	f[myint](myint32(10))
 	f[myint](myfloat(42))
+	f[I](myint(10))
+	f[J](myint(11))
+	f[J](myint32(12))
 }

test/typeparam/typeswitch4.out

@@ -4,3 +4,6 @@ T/myint32 8
 T/myint32 9
 T/myint32 10
 other 42
+T/myint32 10
+other 11
+T/myint32 12