feat: go1.20 introduces slice to array convertibility

Signed-off-by: Maxime Soulé <btik-git@scoubidou.com>

internal/types/reflect.go

@@ -64,13 +64,23 @@ func IsTypeOrConvertible(v reflect.Value, target reflect.Type) (bool, bool) {
 // It handles go 1.17 slice to array pointer convertibility.
 func IsConvertible(v reflect.Value, target reflect.Type) bool {
 	if v.Type().ConvertibleTo(target) {
+		if v.Kind() != reflect.Slice {
+			return true
+		}
+
+		switch target.Kind() {
 		// Since go 1.17, a slice can be convertible to a pointer to an
 		// array, but Convert() may still panic if the slice length is lesser
 		// than array pointed one
-		if v.Kind() != reflect.Slice ||
-			target.Kind() != reflect.Ptr ||
-			target.Elem().Kind() != reflect.Array ||
-			v.Len() >= target.Elem().Len() {
+		case reflect.Ptr:
+			return target.Elem().Kind() != reflect.Array ||
+				v.Len() >= target.Elem().Len()
+		// Since go 1.20, a slice can also be convertible to an array, but
+		// Convert() may still panic if the slice length is lesser than
+		// array one
+		case reflect.Array:
+			return v.Len() >= target.Len()
+		default:
 			return true
 		}
 	}

internal/types/reflect_go117_test.go

@@ -1,11 +1,11 @@
-// Copyright (c) 2021, Maxime Soulé
+// Copyright (c) 2021, 2022, Maxime Soulé
 // All rights reserved.
 //
 // This source code is licensed under the BSD-style license found in the
 // LICENSE file in the root directory of this source tree.
 
-//go:build go1.17
-// +build go1.17
+//go:build go1.17 && !go1.20
+// +build go1.17,!go1.20
 
 package types_test
 

internal/types/reflect_go120_test.go

@@ -0,0 +1,58 @@
+// Copyright (c) 2022, Maxime Soulé
+// All rights reserved.
+//
+// This source code is licensed under the BSD-style license found in the
+// LICENSE file in the root directory of this source tree.
+
+//go:build go1.20
+// +build go1.20
+
+package types_test
+
+import (
+	"reflect"
+	"testing"
+
+	"github.com/maxatome/go-testdeep/internal/test"
+	"github.com/maxatome/go-testdeep/internal/types"
+)
+
+// go1.17 allows to convert []T to *[n]T.
+// go1.20 allows to convert []T to [n]T.
+func TestIsTypeOrConvertible_go117(t *testing.T) {
+	type ArrP *[5]int
+	type Arr [5]int
+
+	// 1.17
+	ok, convertible := types.IsTypeOrConvertible(
+		reflect.ValueOf([]int{1, 2, 3, 4, 5}),
+		reflect.TypeOf((ArrP)(nil)))
+	test.IsTrue(t, ok)
+	test.IsTrue(t, convertible)
+
+	// 1.20
+	ok, convertible = types.IsTypeOrConvertible(
+		reflect.ValueOf([]int{1, 2, 3, 4, 5}),
+		reflect.TypeOf([5]int{}))
+	test.IsTrue(t, ok)
+	test.IsTrue(t, convertible)
+
+	// 1.20
+	ok, convertible = types.IsTypeOrConvertible(
+		reflect.ValueOf([]int{1, 2, 3, 4, 5}),
+		reflect.TypeOf(Arr{}))
+	test.IsTrue(t, ok)
+	test.IsTrue(t, convertible)
+
+	ok, convertible = types.IsTypeOrConvertible(
+		reflect.ValueOf([]int{1, 2, 3, 4}), // not enough items
+		reflect.TypeOf((ArrP)(nil)))
+	test.IsFalse(t, ok)
+	test.IsFalse(t, convertible)
+
+	ok, convertible = types.IsTypeOrConvertible(
+		reflect.ValueOf([]int{1, 2, 3, 4, 5}),
+		reflect.TypeOf(&struct{}{}))
+	test.IsFalse(t, ok)
+	test.IsFalse(t, convertible)
+}