fix: do not traverse struct fields if type has parser or implements TextUnmarshaler (#440)

env.go

@@ -379,7 +379,7 @@ func doParseField(
 	if !refField.CanSet() {
 		return nil
 	}
-	if refField.Kind() == reflect.Ptr && refField.Elem().Kind() == reflect.Struct && !refField.IsNil() {
+	if refField.Kind() == reflect.Ptr && refField.Elem().Kind() == reflect.Struct && !refField.IsNil() && !hasCustomOrTextParserType(refTypeField.Type, opts.FuncMap) {
 		return parseInternal(refField.Interface(), processField, optionsWithEnvPrefix(refTypeField, opts))
 	}
 	if refField.Kind() == reflect.Struct && refField.CanAddr() && refField.Type().Name() == "" {
@@ -404,31 +404,30 @@ func doParseField(
 		refField = refField.Elem()
 	}
 
-	if refField.Kind() == reflect.Struct {
+	if refField.Kind() == reflect.Struct && !hasCustomOrTextParserType(refTypeField.Type, opts.FuncMap) {
 		return doParse(refField, processField, optionsWithEnvPrefix(refTypeField, opts))
 	}
 
-	if isSliceOfStructs(refTypeField) {
+	if isSliceOfStructs(refTypeField, opts) {
 		return doParseSlice(refField, processField, optionsWithEnvPrefix(refTypeField, opts))
 	}
 
 	return nil
 }
 
-func isSliceOfStructs(refTypeField reflect.StructField) bool {
+func isSliceOfStructs(refTypeField reflect.StructField, opts Options) bool {
 	field := refTypeField.Type
 
-	// *[]struct
 	if field.Kind() == reflect.Ptr {
 		field = field.Elem()
-		if field.Kind() == reflect.Slice && field.Elem().Kind() == reflect.Struct {
-			return true
-		}
 	}
 
-	// []struct{}
 	if field.Kind() == reflect.Slice && field.Elem().Kind() == reflect.Struct {
-		return true
+		elemType := field.Elem()
+		if elemType.Kind() == reflect.Ptr {
+			elemType = elemType.Elem()
+		}
+		return !hasCustomOrTextParserType(elemType, opts.FuncMap)
 	}
 
 	return false
@@ -851,3 +850,18 @@ func ToMap(env []string) map[string]string {
 func isInvalidPtr(v reflect.Value) bool {
 	return reflect.Ptr == v.Kind() && v.Elem().Kind() == reflect.Invalid
 }
+
+var textUnmarshalerType = reflect.TypeOf((*encoding.TextUnmarshaler)(nil)).Elem() //nolint:gochecknoglobals
+
+func hasCustomOrTextParserType(t reflect.Type, funcMap map[reflect.Type]ParserFunc) bool {
+	if t.Kind() == reflect.Ptr {
+		t = t.Elem()
+	}
+	if _, ok := funcMap[t]; ok {
+		return true
+	}
+	if t.Implements(textUnmarshalerType) || reflect.PointerTo(t).Implements(textUnmarshalerType) {
+		return true
+	}
+	return false
+}

env_test.go

@@ -2417,3 +2417,66 @@
 		isEqual(t, "", cfg.Foo)
 	})
 }
+
+type customTextUnmarshaler struct {
+	Value string
+}
+
+func (c *customTextUnmarshaler) UnmarshalText(text []byte) error {
+	c.Value = string(text)
+	return nil
+}
+
+func TestUseFieldNameByDefault_URLAndTextUnmarshaler(t *testing.T) {
+	type config struct {
+		URL       url.URL                `env:"URL"`
+		Custom    customTextUnmarshaler  `env:"CUSTOM"`
+		CustomPtr *customTextUnmarshaler `env:"CUSTOM_PTR"`
+	}
+
+	environ := map[string]string{
+		"URL":        "http://example.com/a/b",
+		"PATH":       "/usr/bin",
+		"HOST":       "evil",
+		"CUSTOM":     "custom-value",
+		"CUSTOM_PTR": "custom-ptr-value",
+		"VALUE":      "evil-nested",
+	}
+
+	t.Run("by tag", func(t *testing.T) {
+		var cfg config
+		err := ParseWithOptions(&cfg, Options{Environment: environ})
+		isNoErr(t, err)
+		isEqual(t, "http://example.com/a/b", cfg.URL.String())
+		isEqual(t, "custom-value", cfg.Custom.Value)
+		isEqual(t, "custom-ptr-value", cfg.CustomPtr.Value)
+	})
+
+	t.Run("with UseFieldNameByDefault", func(t *testing.T) {
+		var cfg config
+		err := ParseWithOptions(&cfg, Options{Environment: environ, UseFieldNameByDefault: true})
+		isNoErr(t, err)
+		isEqual(t, "http://example.com/a/b", cfg.URL.String())
+		isEqual(t, "custom-value", cfg.Custom.Value)
+		isEqual(t, "custom-ptr-value", cfg.CustomPtr.Value)
+	})
+
+	t.Run("with UseFieldNameByDefault and RequiredIfNoDef", func(t *testing.T) {
+		var cfg config
+		err := ParseWithOptions(&cfg, Options{
+			Environment: map[string]string{
+				"URL":        "http://example.com/a/b",
+				"CUSTOM":     "custom-value",
+				"CUSTOM_PTR": "custom-ptr-value",
+			},
+			UseFieldNameByDefault: true,
+			RequiredIfNoDef:       true,
+		})
+		isNoErr(t, err)
+		isEqual(t, "http://example.com/a/b", cfg.URL.String())
+		isEqual(t, "custom-value", cfg.Custom.Value)
+		isEqual(t, "custom-ptr-value", cfg.CustomPtr.Value)
+	})
+}
+
+