fix(spanned): Allow internal fields to be in any order

Fixes #789

crates/serde_spanned/src/spanned.rs

@@ -182,25 +182,46 @@ where
  where
  V: serde::de::MapAccess<'de>,
  {
- if visitor.next_key()? != Some(START_FIELD) {
- return Err(serde::de::Error::custom("spanned start key not found"));
+ let mut start: Option<usize> = None;
+ let mut end: Option<usize> = None;
+ let mut value: Option<T> = None;
+ while let Some(key) = visitor.next_key()? {
+ match key {
+ START_FIELD => {
+ if start.is_some() {
+ return Err(serde::de::Error::duplicate_field(START_FIELD));
+ }
+ start = Some(visitor.next_value()?);
+ }
+ END_FIELD => {
+ if end.is_some() {
+ return Err(serde::de::Error::duplicate_field(END_FIELD));
+ }
+ end = Some(visitor.next_value()?);
+ }
+ VALUE_FIELD => {
+ if value.is_some() {
+ return Err(serde::de::Error::duplicate_field(VALUE_FIELD));
+ }
+ value = Some(visitor.next_value()?);
+ }
+ field => {
+ return Err(serde::de::Error::unknown_field(
+ field,
+ &[START_FIELD, END_FIELD, VALUE_FIELD],
+ ));
+ }
+ }
  }
- let start: usize = visitor.next_value()?;
-
- if visitor.next_key()? != Some(END_FIELD) {
- return Err(serde::de::Error::custom("spanned end key not found"));
- }
- let end: usize = visitor.next_value()?;
-
- if visitor.next_key()? != Some(VALUE_FIELD) {
- return Err(serde::de::Error::custom("spanned value key not found"));
+ match (start, end, value) {
+ (Some(start), Some(end), Some(value)) => Ok(Spanned {
+ span: start..end,
+ value,
+ }),
+ (None, _, _) => Err(serde::de::Error::missing_field(START_FIELD)),
+ (_, None, _) => Err(serde::de::Error::missing_field(END_FIELD)),
+ (_, _, None) => Err(serde::de::Error::missing_field(VALUE_FIELD)),
  }
- let value: T = visitor.next_value()?;
-
- Ok(Spanned {
- span: start..end,
- value,
- })
  }
  }