Fix UnexpectedEof when deserialize xs:lists and newtypes

Changelog.md

@@ -20,6 +20,10 @@ MSRV bumped to 1.56! Crate now uses Rust 2021 edition.
 
 ### Bug Fixes
 
+- [#660]: Fixed incorrect deserialization of `xs:list`s from empty tags (`<tag/>`
+  or `<tag></tag>`). Previously an `DeError::UnexpectedEof")` was returned in that case
+- [#580]: Fixed incorrect deserialization of vectors of newtypes from sequences of tags.
+
 ### Misc Changes
 
 - [#643]: Bumped MSRV to 1.56. In practice the previous MSRV was incorrect in many cases.
@@ -32,11 +36,13 @@ MSRV bumped to 1.56! Crate now uses Rust 2021 edition.
   (and newly added `ElementWriter::write_inner_content_async` of course).
 
 [#545]: https://github.com/tafia/quick-xml/pull/545
+[#580]: https://github.com/tafia/quick-xml/issues/580
 [#619]: https://github.com/tafia/quick-xml/issues/619
 [#635]: https://github.com/tafia/quick-xml/pull/635
 [#643]: https://github.com/tafia/quick-xml/pull/643
 [#649]: https://github.com/tafia/quick-xml/pull/646
 [#651]: https://github.com/tafia/quick-xml/pull/651
+[#660]: https://github.com/tafia/quick-xml/pull/660
 
 
 ## 0.30.0 -- 2023-07-23

src/de/map.rs

@@ -373,6 +373,52 @@ macro_rules! forward {
 /// A deserializer for a value of map or struct. That deserializer slightly
 /// differently processes events for a primitive types and sequences than
 /// a [`Deserializer`].
+///
+/// This deserializer can see two kind of events at the start:
+/// - [`DeEvent::Text`]
+/// - [`DeEvent::Start`]
+///
+/// which represents two possible variants of items:
+/// ```xml
+/// <item>A tag item</item>
+/// A text item
+/// <yet another="tag item"/>
+/// ```
+///
+/// This deserializer are very similar to a [`SeqItemDeserializer`]. The only difference
+/// in the `deserialize_seq` method. This deserializer will act as an iterator
+/// over tags / text within it's parent tag, whereas the [`SeqItemDeserializer`]
+/// will represent sequences as an `xs:list`.
+///
+/// This deserializer processes items as following:
+/// - primitives (numbers, booleans, strings, characters) are deserialized either
+///   from a text content, or unwrapped from a one level of a tag. So, `123` and
+///   `<int>123</int>` both can be deserialized into an `u32`;
+/// - `Option`:
+///   - empty text of [`DeEvent::Text`] is deserialized as `None`;
+///   - everything else are deserialized as `Some` using the same deserializer,
+///     including `<tag/>` or `<tag></tag>`;
+/// - units (`()`) and unit structs consumes the whole text or element subtree;
+/// - newtype structs are deserialized by forwarding deserialization of inner type
+///   with the same deserializer;
+/// - sequences, tuples and tuple structs are deserialized by iterating within the
+///   parent tag and deserializing each tag or text content using [`SeqItemDeserializer`];
+/// - structs and maps are deserialized using new instance of [`MapAccess`];
+/// - enums:
+///   - in case of [`DeEvent::Text`] event the text content is deserialized as
+///     a `$text` variant. Enum content is deserialized from the text using
+///     [`SimpleTypeDeserializer`];
+///   - in case of [`DeEvent::Start`] event the tag name is deserialized as
+///     an enum tag, and the content inside are deserialized as an enum content.
+///     Depending on a variant kind deserialization is performed as:
+///     - unit variants: consuming text content or a subtree;
+///     - newtype variants: forward deserialization to the inner type using
+///       this deserializer;
+///     - tuple variants: call [`deserialize_tuple`] of this deserializer;
+///     - struct variants: call [`deserialize_struct`] of this deserializer.
+///
+/// [`deserialize_tuple`]: #method.deserialize_tuple
+/// [`deserialize_struct`]: #method.deserialize_struct
 struct MapValueDeserializer<'de, 'a, 'm, R, E>
 where
     R: XmlRead<'de>,
@@ -485,7 +531,6 @@ where
 
     forward!(deserialize_unit);
 
-    forward!(deserialize_map);
     forward!(deserialize_struct(
         name: &'static str,
         fields: &'static [&'static str]
@@ -497,7 +542,6 @@ where
     ));
 
     forward!(deserialize_any);
-    forward!(deserialize_ignored_any);
 
     fn deserialize_option<V>(self, visitor: V) -> Result<V::Value, DeError>
     where
@@ -506,6 +550,19 @@ where
         deserialize_option!(self.map.de, self, visitor)
     }
 
+    /// Forwards deserialization of the inner type. Always calls [`Visitor::visit_newtype_struct`]
+    /// with the same deserializer.
+    fn deserialize_newtype_struct<V>(
+        self,
+        _name: &'static str,
+        visitor: V,
+    ) -> Result<V::Value, Self::Error>
+    where
+        V: Visitor<'de>,
+    {
+        visitor.visit_newtype_struct(self)
+    }
+
     /// Deserializes each `<tag>` in
     /// ```xml
     /// <any-tag>
@@ -716,7 +773,59 @@ where
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
-/// A deserializer for a single item of a sequence.
+/// A deserializer for a single item of a mixed sequence of tags and text.
+///
+/// This deserializer can see two kind of events at the start:
+/// - [`DeEvent::Text`]
+/// - [`DeEvent::Start`]
+///
+/// which represents two possible variants of items:
+/// ```xml
+/// <item>A tag item</item>
+/// A text item
+/// <yet another="tag item"/>
+/// ```
+///
+/// This deserializer are very similar to a [`MapValueDeserializer`]. The only difference
+/// in the `deserialize_seq` method. This deserializer will perform deserialization
+/// from the textual content (the text itself in case of [`DeEvent::Text`] event
+/// and the text between tags in case of [`DeEvent::Start`] event), whereas
+/// the [`MapValueDeserializer`] will iterate over tags / text within it's parent tag.
+///
+/// This deserializer processes items as following:
+/// - primitives (numbers, booleans, strings, characters) are deserialized either
+///   from a text content, or unwrapped from a one level of a tag. So, `123` and
+///   `<int>123</int>` both can be deserialized into an `u32`;
+/// - `Option`:
+///   - empty text of [`DeEvent::Text`] is deserialized as `None`;
+///   - everything else are deserialized as `Some` using the same deserializer,
+///     including `<tag/>` or `<tag></tag>`;
+/// - units (`()`) and unit structs consumes the whole text or element subtree;
+/// - newtype structs are deserialized as tuple structs with one element;
+/// - sequences, tuples and tuple structs are deserialized using [`SimpleTypeDeserializer`]
+///   (this is the difference):
+///   - in case of [`DeEvent::Text`] event text content passed to the deserializer directly;
+///   - in case of [`DeEvent::Start`] event the start and end tags are stripped,
+///     and text between them is passed to [`SimpleTypeDeserializer`]. If the tag
+///     contains something else other than text, an error is returned, but if it
+///     contains a text and something else (for example, `<item>text<tag/></item>`),
+///     then the trail is just ignored;
+/// - structs and maps are deserialized using new [`MapAccess`];
+/// - enums:
+///   - in case of [`DeEvent::Text`] event the text content is deserialized as
+///     a `$text` variant. Enum content is deserialized from the text using
+///     [`SimpleTypeDeserializer`];
+///   - in case of [`DeEvent::Start`] event the tag name is deserialized as
+///     an enum tag, and the content inside are deserialized as an enum content.
+///     Depending on a variant kind deserialization is performed as:
+///     - unit variants: consuming text content or a subtree;
+///     - newtype variants: forward deserialization to the inner type using
+///       this deserializer;
+///     - tuple variants: deserialize it as an `xs:list`;
+///     - struct variants: call [`deserialize_struct`] of this deserializer.
+///
+/// [`deserialize_tuple`]: #method.deserialize_tuple
+/// [`deserialize_struct`]: #method.deserialize_struct
 struct SeqItemDeserializer<'de, 'a, 'm, R, E>
 where
     R: XmlRead<'de>,
@@ -754,7 +863,6 @@ where
 
     forward!(deserialize_unit);
 
-    forward!(deserialize_map);
     forward!(deserialize_struct(
         name: &'static str,
         fields: &'static [&'static str]
@@ -766,7 +874,6 @@ where
     ));
 
     forward!(deserialize_any);
-    forward!(deserialize_ignored_any);
 
     fn deserialize_option<V>(self, visitor: V) -> Result<V::Value, DeError>
     where
@@ -775,6 +882,20 @@ where
         deserialize_option!(self.map.de, self, visitor)
     }
 
+    /// Forwards deserialization of the inner type. Always calls [`Visitor::visit_newtype_struct`]
+    /// with the [`SimpleTypeDeserializer`].
+    fn deserialize_newtype_struct<V>(
+        mut self,
+        _name: &'static str,
+        visitor: V,
+    ) -> Result<V::Value, Self::Error>
+    where
+        V: Visitor<'de>,
+    {
+        let text = self.read_string()?;
+        visitor.visit_newtype_struct(SimpleTypeDeserializer::from_text(text))
+    }
+
     /// This method deserializes a sequence inside of element that itself is a
     /// sequence element:
     ///
@@ -787,34 +908,12 @@ where
     ///   ...
     /// </>
     /// ```
-    fn deserialize_seq<V>(self, visitor: V) -> Result<V::Value, Self::Error>
+    fn deserialize_seq<V>(mut self, visitor: V) -> Result<V::Value, Self::Error>
     where
         V: Visitor<'de>,
     {
-        match self.map.de.next()? {
-            DeEvent::Text(e) => {
-                SimpleTypeDeserializer::from_text_content(e).deserialize_seq(visitor)
-            }
-            // This is a sequence element. We cannot treat it as another flatten
-            // sequence if type will require `deserialize_seq` We instead forward
-            // it to `xs:simpleType` implementation
-            DeEvent::Start(e) => {
-                let value = match self.map.de.next()? {
-                    DeEvent::Text(e) => {
-                        SimpleTypeDeserializer::from_text_content(e).deserialize_seq(visitor)
-                    }
-                    e => Err(DeError::Unsupported(
-                        format!("unsupported event {:?}", e).into(),
-                    )),
-                };
-                // TODO: May be assert that here we expect only matching closing tag?
-                self.map.de.read_to_end(e.name())?;
-                value
-            }
-            // SAFETY: we use that deserializer only when Start(element) or Text
-            // event was peeked already
-            _ => unreachable!(),
-        }
+        let text = self.read_string()?;
+        SimpleTypeDeserializer::from_text(text).deserialize_seq(visitor)
     }
 
     #[inline]

src/de/mod.rs

@@ -1904,18 +1904,6 @@ macro_rules! deserialize_primitives {
             self.deserialize_unit(visitor)
         }
 
-        /// Representation of the newtypes the same as one-element [tuple](#method.deserialize_tuple).
-        fn deserialize_newtype_struct<V>(
-            self,
-            _name: &'static str,
-            visitor: V,
-        ) -> Result<V::Value, DeError>
-        where
-            V: Visitor<'de>,
-        {
-            self.deserialize_tuple(1, visitor)
-        }
-
         /// Representation of tuples the same as [sequences](#method.deserialize_seq).
         fn deserialize_tuple<V>(self, _len: usize, visitor: V) -> Result<V::Value, DeError>
         where
@@ -1937,13 +1925,32 @@ macro_rules! deserialize_primitives {
             self.deserialize_tuple(len, visitor)
         }
 
+        /// Forwards deserialization to the [`deserialize_struct`](#method.deserialize_struct)
+        /// with empty name and fields.
+        #[inline]
+        fn deserialize_map<V>(self, visitor: V) -> Result<V::Value, DeError>
+        where
+            V: Visitor<'de>,
+        {
+            self.deserialize_struct("", &[], visitor)
+        }
+
         /// Identifiers represented as [strings](#method.deserialize_str).
         fn deserialize_identifier<V>(self, visitor: V) -> Result<V::Value, DeError>
         where
             V: Visitor<'de>,
         {
             self.deserialize_str(visitor)
         }
+
+        /// Forwards deserialization to the [`deserialize_unit`](#method.deserialize_unit).
+        #[inline]
+        fn deserialize_ignored_any<V>(self, visitor: V) -> Result<V::Value, DeError>
+        where
+            V: Visitor<'de>,
+        {
+            self.deserialize_unit(visitor)
+        }
     };
 }
 
@@ -2820,30 +2827,36 @@ where
         }
     }
 
-    fn deserialize_enum<V>(
+    /// Forwards deserialization of the inner type. Always calls [`Visitor::visit_newtype_struct`]
+    /// with the same deserializer.
+    fn deserialize_newtype_struct<V>(
         self,
         _name: &'static str,
-        _variants: &'static [&'static str],
         visitor: V,
     ) -> Result<V::Value, DeError>
     where
         V: Visitor<'de>,
     {
-        visitor.visit_enum(var::EnumAccess::new(self))
+        visitor.visit_newtype_struct(self)
     }
 
-    fn deserialize_seq<V>(self, visitor: V) -> Result<V::Value, DeError>
+    fn deserialize_enum<V>(
+        self,
+        _name: &'static str,
+        _variants: &'static [&'static str],
+        visitor: V,
+    ) -> Result<V::Value, DeError>
     where
         V: Visitor<'de>,
     {
-        visitor.visit_seq(self)
+        visitor.visit_enum(var::EnumAccess::new(self))
     }
 
-    fn deserialize_map<V>(self, visitor: V) -> Result<V::Value, DeError>
+    fn deserialize_seq<V>(self, visitor: V) -> Result<V::Value, DeError>
     where
         V: Visitor<'de>,
     {
-        self.deserialize_struct("", &[], visitor)
+        visitor.visit_seq(self)
     }
 
     fn deserialize_option<V>(self, visitor: V) -> Result<V::Value, DeError>
@@ -2853,39 +2866,13 @@ where
         deserialize_option!(self, self, visitor)
     }
 
-    /// Always call `visitor.visit_unit()` because returned value ignored in any case.
-    ///
-    /// This method consumes any single [event][DeEvent] except the [`Start`]
-    /// event, in which case all events up to and including corresponding [`End`]
-    /// event will be consumed.
-    ///
-    /// This method returns error if current event is [`End`] or [`Eof`].
-    ///
-    /// [`Start`]: DeEvent::Start
-    /// [`End`]: DeEvent::End
-    /// [`Eof`]: DeEvent::Eof
-    fn deserialize_ignored_any<V>(self, visitor: V) -> Result<V::Value, DeError>
-    where
-        V: Visitor<'de>,
-    {
-        match self.next()? {
-            DeEvent::Start(e) => self.read_to_end(e.name())?,
-            DeEvent::End(e) => return Err(DeError::UnexpectedEnd(e.name().as_ref().to_owned())),
-            DeEvent::Eof => return Err(DeError::UnexpectedEof),
-            _ => (),
-        }
-        visitor.visit_unit()
-    }
-
     fn deserialize_any<V>(self, visitor: V) -> Result<V::Value, DeError>
     where
         V: Visitor<'de>,
     {
         match self.peek()? {
-            DeEvent::Start(_) => self.deserialize_map(visitor),
-            // Redirect to deserialize_unit in order to consume an event and return an appropriate error
-            DeEvent::End(_) | DeEvent::Eof => self.deserialize_unit(visitor),
-            _ => self.deserialize_string(visitor),
+            DeEvent::Text(_) => self.deserialize_str(visitor),
+            _ => self.deserialize_map(visitor),
         }
     }
 }