feat: implement UnmarshalerError

decode.go

@@ -757,7 +757,7 @@ func (d *Decoder) decodeByUnmarshaler(ctx context.Context, dst reflect.Value, sr
 			return err
 		}
 		if err := unmarshaler(ptrValue.Interface(), b); err != nil {
-			return err
+			return errors.ErrUnmarshaler(err, dst.Type(), src.GetToken())
 		}
 		return nil
 	}
@@ -769,7 +769,7 @@ func (d *Decoder) decodeByUnmarshaler(ctx context.Context, dst reflect.Value, sr
 			return err
 		}
 		if err := unmarshaler.UnmarshalYAML(ctx, b); err != nil {
-			return err
+			return errors.ErrUnmarshaler(err, dst.Type(), src.GetToken())
 		}
 		return nil
 	}
@@ -780,7 +780,7 @@ func (d *Decoder) decodeByUnmarshaler(ctx context.Context, dst reflect.Value, sr
 			return err
 		}
 		if err := unmarshaler.UnmarshalYAML(b); err != nil {
-			return err
+			return errors.ErrUnmarshaler(err, dst.Type(), src.GetToken())
 		}
 		return nil
 	}
@@ -796,7 +796,7 @@ func (d *Decoder) decodeByUnmarshaler(ctx context.Context, dst reflect.Value, sr
 			}
 			return nil
 		}); err != nil {
-			return err
+			return errors.ErrUnmarshaler(err, dst.Type(), src.GetToken())
 		}
 		return nil
 	}
@@ -812,22 +812,22 @@ func (d *Decoder) decodeByUnmarshaler(ctx context.Context, dst reflect.Value, sr
 			}
 			return nil
 		}); err != nil {
-			return err
+			return errors.ErrUnmarshaler(err, dst.Type(), src.GetToken())
 		}
 		return nil
 	}
 
 	if unmarshaler, ok := iface.(NodeUnmarshaler); ok {
 		if err := unmarshaler.UnmarshalYAML(src); err != nil {
-			return err
+			return errors.ErrUnmarshaler(err, dst.Type(), src.GetToken())
 		}
 
 		return nil
 	}
 
 	if unmarshaler, ok := iface.(NodeUnmarshalerContext); ok {
 		if err := unmarshaler.UnmarshalYAML(ctx, src); err != nil {
-			return err
+			return errors.ErrUnmarshaler(err, dst.Type(), src.GetToken())
 		}
 
 		return nil
@@ -845,7 +845,7 @@ func (d *Decoder) decodeByUnmarshaler(ctx context.Context, dst reflect.Value, sr
 		b, ok := d.unmarshalableText(src)
 		if ok {
 			if err := unmarshaler.UnmarshalText(b); err != nil {
-				return err
+				return errors.ErrUnmarshaler(err, dst.Type(), src.GetToken())
 			}
 			return nil
 		}
@@ -863,7 +863,7 @@ func (d *Decoder) decodeByUnmarshaler(ctx context.Context, dst reflect.Value, sr
 			}
 			jsonBytes = bytes.TrimRight(jsonBytes, "\n")
 			if err := unmarshaler.UnmarshalJSON(jsonBytes); err != nil {
-				return err
+				return errors.ErrUnmarshaler(err, dst.Type(), src.GetToken())
 			}
 			return nil
 		}
@@ -872,9 +872,7 @@ func (d *Decoder) decodeByUnmarshaler(ctx context.Context, dst reflect.Value, sr
 	return errors.New("does not implemented Unmarshaler")
 }
 
-var (
-	astNodeType = reflect.TypeOf((*ast.Node)(nil)).Elem()
-)
+var astNodeType = reflect.TypeOf((*ast.Node)(nil)).Elem()
 
 func (d *Decoder) decodeValue(ctx context.Context, dst reflect.Value, src ast.Node) error {
 	d.stepIn()
@@ -1381,8 +1379,7 @@ func (d *Decoder) decodeStruct(ctx context.Context, dst reflect.Value, src ast.N
 				if foundErr != nil {
 					continue
 				}
-				var te *errors.TypeError
-				if errors.As(err, &te) {
+				if te, ok := err.(*errors.TypeError); ok {
 					if te.StructFieldName != nil {
 						fieldName := fmt.Sprintf("%s.%s", structType.Name(), *te.StructFieldName)
 						te.StructFieldName = &fieldName
@@ -1417,8 +1414,7 @@ func (d *Decoder) decodeStruct(ctx context.Context, dst reflect.Value, src ast.N
 			if foundErr != nil {
 				continue
 			}
-			var te *errors.TypeError
-			if errors.As(err, &te) {
+			if te, ok := err.(*errors.TypeError); ok {
 				fieldName := fmt.Sprintf("%s.%s", structType.Name(), field.Name)
 				te.StructFieldName = &fieldName
 				foundErr = te

decode_test.go

@@ -2531,6 +2531,9 @@ func TestUnmarshalablePtrString(t *testing.T) {
 type unmarshalableIntValue int
 
 func (v *unmarshalableIntValue) UnmarshalYAML(raw []byte) error {
+	if string(raw) == "yamlerr" {
+		return yaml.Unmarshal(raw, (*int)(v))
+	}
 	i, err := strconv.Atoi(string(raw))
 	if err != nil {
 		return err
@@ -2604,6 +2607,38 @@ func TestUnmarshalablePtrInt(t *testing.T) {
 	})
 }
 
+func TestUnmarshalableErrors(t *testing.T) {
+	t.Run("wrapped error", func(t *testing.T) {
+		t.Parallel()
+		var container unmarshalableIntContainer
+		err := yaml.Unmarshal([]byte(`value: atoierr`), &container)
+		if err == nil {
+			t.Fatal("expected to error")
+		}
+		var unmarshalerErr *errors.UnmarshalerError
+		if !errors.As(err, &unmarshalerErr) {
+			t.Fatalf("expected UnmarshalerError but got: %s", err)
+		}
+		expectedErr := `yaml_test.unmarshalableIntValue: strconv.Atoi: parsing "atoierr": invalid syntax`
+		if !strings.Contains(err.Error(), expectedErr) {
+			t.Fatalf("expected error message: %s to contain: %s", err.Error(), expectedErr)
+		}
+	})
+
+	t.Run("nested yaml decode error", func(t *testing.T) {
+		t.Parallel()
+		var container unmarshalableIntContainer
+		err := yaml.Unmarshal([]byte(`value: yamlerr`), &container)
+		if err == nil {
+			t.Fatal("expected to error")
+		}
+		expectedErr := `cannot unmarshal into Go value of type yaml_test.unmarshalableIntValue: cannot unmarshal string into Go value of type int`
+		if !strings.Contains(err.Error(), expectedErr) {
+			t.Fatalf("expected error message: %s to contain: %s", err.Error(), expectedErr)
+		}
+	})
+}
+
 type literalContainer struct {
 	v string
 }
@@ -3206,6 +3241,9 @@ type unmarshableMapKey struct {
 }
 
 func (mk *unmarshableMapKey) UnmarshalYAML(b []byte) error {
+	if string(b) == "errkey" {
+		return errors.New("invalid map key")
+	}
 	mk.Key = string(b)
 	return nil
 }
@@ -3401,6 +3439,15 @@ func TestMapKeyCustomUnmarshaler(t *testing.T) {
 	if val != "value" {
 		t.Fatalf("expected to have value \"value\", but got %q", val)
 	}
+
+	expectErr := "invalid map key"
+	err := yaml.Unmarshal([]byte(`errkey: value`), &m)
+	if err == nil {
+		t.Fatal("expected error but got nil")
+	}
+	if !strings.Contains(err.Error(), expectErr) {
+		t.Fatalf("error message %q should contain %q", err.Error(), expectErr)
+	}
 }
 
 type bytesUnmershalerWithMapAlias struct{}

error.go

@@ -26,6 +26,7 @@ type (
 	DuplicateKeyError       = errors.DuplicateKeyError
 	UnknownFieldError       = errors.UnknownFieldError
 	UnexpectedNodeTypeError = errors.UnexpectedNodeTypeError
+	UnmarshalerError        = errors.UnmarshalerError
 	Error                   = errors.Error
 )
 

internal/errors/error.go

@@ -35,6 +35,7 @@ var (
 	_ Error = new(DuplicateKeyError)
 	_ Error = new(UnknownFieldError)
 	_ Error = new(UnexpectedNodeTypeError)
+	_ Error = new(UnmarshalerError)
 )
 
 type SyntaxError struct {
@@ -71,6 +72,12 @@ type UnexpectedNodeTypeError struct {
 	Token    *token.Token
 }
 
+type UnmarshalerError struct {
+	Wrapped error
+	DstType reflect.Type
+	Token   *token.Token
+}
+
 // ErrSyntax create syntax error instance with message and token
 func ErrSyntax(msg string, tk *token.Token) *SyntaxError {
 	return &SyntaxError{
@@ -121,6 +128,24 @@ func ErrUnexpectedNodeType(actual, expected ast.NodeType, tk *token.Token) *Unex
 	}
 }
 
+func ErrUnmarshaler(wrapped error, dstType reflect.Type, tk *token.Token) error {
+	if wrapped == nil {
+		return nil
+	}
+	if yamlErr, ok := wrapped.(Error); ok {
+		return &UnmarshalerError{
+			Wrapped: errors.New(yamlErr.GetMessage()),
+			DstType: dstType,
+			Token:   tk,
+		}
+	}
+	return &UnmarshalerError{
+		Wrapped: wrapped,
+		DstType: dstType,
+		Token:   tk,
+	}
+}
+
 func (e *SyntaxError) GetMessage() string {
 	return e.Message
 }
@@ -232,6 +257,30 @@ func (e *UnexpectedNodeTypeError) msg() string {
 	return fmt.Sprintf("%s was used where %s is expected", e.Actual.YAMLName(), e.Expected.YAMLName())
 }
 
+func (e *UnmarshalerError) GetMessage() string {
+	return e.msg()
+}
+
+func (e *UnmarshalerError) GetToken() *token.Token {
+	return e.Token
+}
+
+func (e *UnmarshalerError) Error() string {
+	return e.FormatError(defaultFormatColor, defaultIncludeSource)
+}
+
+func (e *UnmarshalerError) FormatError(colored, inclSource bool) string {
+	return FormatError(e.msg(), e.Token, colored, inclSource)
+}
+
+func (e *UnmarshalerError) Unwrap() error {
+	return e.Wrapped
+}
+
+func (e *UnmarshalerError) msg() string {
+	return fmt.Sprintf("cannot unmarshal into Go value of type %s: %s", e.DstType, e.Wrapped.Error())
+}
+
 func FormatError(errMsg string, token *token.Token, colored, inclSource bool) string {
 	var pp printer.Printer
 	if token == nil {