DefaultTypeAdapter: Add support for missing custom scalars

The default type adapter already supports some custom scalar types but
not all, this change adds the missing ones. The most only used one is
likely string.

common/types/provider.go

@@ -590,12 +590,33 @@ func nativeToValue(a Adapter, value any) (ref.Val, bool) {
 			return NewDynamicMap(a, v), true
 		// type aliases of primitive types cannot be asserted as that type, but rather need
 		// to be downcast to int32 before being converted to a CEL representation.
+		case reflect.Bool:
+			boolTupe := reflect.TypeOf(false)
+			return Bool(refValue.Convert(boolTupe).Interface().(bool)), true
+		case reflect.Int:
+			intType := reflect.TypeOf(int(0))
+			return Int(refValue.Convert(intType).Interface().(int)), true
+		case reflect.Int8:
+			intType := reflect.TypeOf(int8(0))
+			return Int(refValue.Convert(intType).Interface().(int8)), true
+		case reflect.Int16:
+			intType := reflect.TypeOf(int16(0))
+			return Int(refValue.Convert(intType).Interface().(int16)), true
 		case reflect.Int32:
 			intType := reflect.TypeOf(int32(0))
 			return Int(refValue.Convert(intType).Interface().(int32)), true
 		case reflect.Int64:
 			intType := reflect.TypeOf(int64(0))
 			return Int(refValue.Convert(intType).Interface().(int64)), true
+		case reflect.Uint:
+			uintType := reflect.TypeOf(uint(0))
+			return Uint(refValue.Convert(uintType).Interface().(uint)), true
+		case reflect.Uint8:
+			uintType := reflect.TypeOf(uint8(0))
+			return Uint(refValue.Convert(uintType).Interface().(uint8)), true
+		case reflect.Uint16:
+			uintType := reflect.TypeOf(uint16(0))
+			return Uint(refValue.Convert(uintType).Interface().(uint16)), true
 		case reflect.Uint32:
 			uintType := reflect.TypeOf(uint32(0))
 			return Uint(refValue.Convert(uintType).Interface().(uint32)), true
@@ -608,6 +629,9 @@ func nativeToValue(a Adapter, value any) (ref.Val, bool) {
 		case reflect.Float64:
 			doubleType := reflect.TypeOf(float64(0))
 			return Double(refValue.Convert(doubleType).Interface().(float64)), true
+		case reflect.String:
+			stringType := reflect.TypeOf("")
+			return String(refValue.Convert(stringType).Interface().(string)), true
 		}
 	}
 	return nil, false

common/types/provider_test.go

@@ -758,12 +758,19 @@ func TestNativeToValue_Primitive(t *testing.T) {
 	expectNativeToValue(t, &rBytes, rBytes)
 
 	// Extensions to core types.
+	expectNativeToValue(t, testInt(1), Int(1))
+	expectNativeToValue(t, testInt8(1), Int(1))
+	expectNativeToValue(t, testInt16(1), Int(1))
 	expectNativeToValue(t, testInt32(1), Int(1))
 	expectNativeToValue(t, testInt64(-100), Int(-100))
+	expectNativeToValue(t, testUint(1), Uint(1))
+	expectNativeToValue(t, testUint8(1), Uint(1))
+	expectNativeToValue(t, testUint16(1), Uint(1))
 	expectNativeToValue(t, testUint32(2), Uint(2))
 	expectNativeToValue(t, testUint64(3), Uint(3))
 	expectNativeToValue(t, testFloat32(4.5), Double(4.5))
 	expectNativeToValue(t, testFloat64(-5.1), Double(-5.1))
+	expectNativeToValue(t, testString("foo"), String("foo"))
 
 	// Null conversion test.
 	expectNativeToValue(t, nil, NullValue)
@@ -870,12 +877,20 @@ func BenchmarkTypeProviderCopy(b *testing.B) {
 type nonConvertible struct {
 	Field string
 }
+type testBool bool
+type testInt int
+type testInt8 int8
+type testInt16 int16
 type testInt32 int32
 type testInt64 int64
+type testUint uint
+type testUint8 uint8
+type testUint16 uint16
 type testUint32 uint32
 type testUint64 uint64
 type testFloat32 float32
 type testFloat64 float64
+type testString string
 
 func newTestRegistry(t *testing.T, types ...proto.Message) *Registry {
 	t.Helper()