Repository: goccy/go-yaml (go)

Issue:
Two levels of inline depth results in reflection error 
Hey @goccy,

I've added the following test:
```go
func TestDecoder_InlineDoubleBase(t *testing.T) {
	type Base struct {
		A int
		B string
	}
	yml := `---
a: 1
b: hello
`
	type Base2 struct {
		Base *Base `yaml:",inline"`
	}
	var v struct {
		Base2 *Base2 `yaml:",inline"`
	}
	if err := yaml.NewDecoder(strings.NewReader(yml), yaml.Strict()).Decode(&v); err != nil {
		t.Fatalf("%+v", err)
	}
	if v.Base2.Base.A != 1 {
		t.Fatal("failed to decode with inline key")
	}
	if v.Base2.Base.B != "hello" {
		t.Fatal("failed to decode with inline key")
	}
}
```

the test resulted in the following reflect panic
```
--- FAIL: TestDecoder_InlineDoubleTest (0.00s)
panic: reflect: call of reflect.Value.FieldByName on ptr Value [recovered]
        panic: reflect: call of reflect.Value.FieldByName on ptr Value

goroutine 27 [running]:
testing.tRunner.func1.1(0x12099c0, 0xc00032c920)
        /usr/local/Cellar/go/1.14/libexec/src/testing/testing.go:941 +0x3d0
testing.tRunner.func1(0xc0003306c0)
        /usr/local/Cellar/go/1.14/libexec/src/testing/testing.go:944 +0x3f9
panic(0x12099c0, 0xc00032c920)
        /usr/local/Cellar/go/1.14/libexec/src/runtime/panic.go:967 +0x15d
reflect.flag.mustBe(...)
        /usr/local/Cellar/go/1.14/libexec/src/reflect/value.go:208
reflect.Value.FieldByName(0x11efee0, 0xc0002c5bc8, 0x196, 0x11e87a4, 0x4, 0x11eff01, 0x11e87aa, 0xe)
        /usr/local/Cellar/go/1.14/libexec/src/reflect/value.go:880 +0x1ed
github.com/goccy/go-yaml.(*Decoder).deleteStructKeys(0xc0003034a0, 0x11efee0, 0xc0002c5bc8, 0x196, 0xc0003343c0, 0x12153e0, 0xc0002c5c20)
        /Users/user/work/go-yaml/decode.go:386 +0x238
github.com/goccy/go-yaml.(*Decoder).decodeStruct(0xc0003034a0, 0x1211da0, 0xc0002c5bc8, 0x199, 0x12ae720, 0xc000320d00, 0x28, 0x121d6c0)
        /Users/user/work/go-yaml/decode.go:788 +0xde7
github.com/goccy/go-yaml.(*Decoder).decodeValue(0xc0003034a0, 0x1211da0, 0xc0002c5bc8, 0x199, 0x12ae720, 0xc000320d00, 0x0, 0x12)
        /Users/user/work/go-yaml/decode.go:474 +0x1b0a
github.com/goccy/go-yaml.(*Decoder).decode(0xc0003034a0, 0x11f5460, 0xc0002c5bc8, 0x16, 0x11f5460, 0x1415800)
        /Users/user/work/go-yaml/decode.go:1244 +0xd2
github.com/goccy/go-yaml.(*Decoder).Decode(0xc0003034a0, 0x11f5460, 0xc0002c5bc8, 0x10565f9, 0x7380299ca20cb)
        /Users/user/work/go-yaml/decode.go:1273 +0x272
github.com/goccy/go-yaml_test.TestDecoder_Inline(0xc0003306c0)
        /Users/user/work/go-yaml/decode_test.go:1315 +0x1da
testing.tRunner(0xc0003306c0, 0x125f6f0)
        /usr/local/Cellar/go/1.14/libexec/src/testing/testing.go:992 +0xdc
created by testing.(*T).Run
        /usr/local/Cellar/go/1.14/libexec/src/testing/testing.go:1043 +0x357
FAIL    github.com/goccy/go-yaml        0.519s
FAIL

```

Pull request description:
Fix reflection error in deleteStructKeys
fix #125 


Patch:
diff --git a/decode.go b/decode.go
index 896d8a7..bbee6d0 100644
--- a/decode.go
+++ b/decode.go
@@ -361,8 +361,7 @@ func errDuplicateKey(msg string, tk *token.Token) *duplicateKeyError {
 	return &duplicateKeyError{err: errors.ErrSyntax(msg, tk)}
 }
 
-func (d *Decoder) deleteStructKeys(structValue reflect.Value, unknownFields map[string]ast.Node) error {
-	structType := structValue.Type()
+func (d *Decoder) deleteStructKeys(structType reflect.Type, unknownFields map[string]ast.Node) error {
 	if structType.Kind() == reflect.Ptr {
 		structType = structType.Elem()
 	}
@@ -383,7 +382,7 @@ func (d *Decoder) deleteStructKeys(structValue reflect.Value, unknownFields map[
 		}
 
 		if structField.IsInline {
-			d.deleteStructKeys(structValue.FieldByName(field.Name), unknownFields)
+			d.deleteStructKeys(field.Type, unknownFields)
 		} else {
 			delete(unknownFields, structField.RenderName)
 		}
@@ -785,7 +784,7 @@ func (d *Decoder) decodeStruct(dst reflect.Value, src ast.Node) error {
 					err = nil
 				}
 
-				if err = d.deleteStructKeys(fieldValue, unknownFields); err != nil {
+				if err = d.deleteStructKeys(fieldValue.Type(), unknownFields); err != nil {
 					return errors.Wrapf(err, "cannot delete struct keys")
 				}
 			}


Test patch:
diff --git a/decode_test.go b/decode_test.go
index aacf6f1..ef995bb 100644
--- a/decode_test.go
+++ b/decode_test.go
@@ -1323,6 +1323,32 @@ c: true
 	if !v.C {
 		t.Fatal("failed to decode with inline key")
 	}
+
+	t.Run("multiple inline with strict", func(t *testing.T) {
+		type Base struct {
+			A int
+			B string
+		}
+		type Base2 struct {
+			Base *Base `yaml:",inline"`
+		}
+		yml := `---
+a: 1
+b: hello
+`
+		var v struct {
+			Base2 *Base2 `yaml:",inline"`
+		}
+		if err := yaml.NewDecoder(strings.NewReader(yml), yaml.Strict()).Decode(&v); err != nil {
+			t.Fatalf("%+v", err)
+		}
+		if v.Base2.Base.A != 1 {
+			t.Fatal("failed to decode with inline key")
+		}
+		if v.Base2.Base.B != "hello" {
+			t.Fatal("failed to decode with inline key")
+		}
+	})
 }
 
 func TestDecoder_InlineAndConflictKey(t *testing.T) {