Remove DeError::ExpectedStart, call Visitor::visit_borrowed_str o…

…r `visit_string` instead

It is responsibility of a `Visitor` to return an error if the provided data can not be handled

src/de/mod.rs

@@ -2821,7 +2821,13 @@ where
             // SAFETY: The reader is guaranteed that we don't have unmatched tags
             // If we here, then out deserializer has a bug
             DeEvent::End(e) => unreachable!("{:?}", e),
-            DeEvent::Text(_) => Err(DeError::ExpectedStart),
+            // Deserializer methods are only hints, if deserializer could not satisfy
+            // request, it should return the data that it has. It is responsibility
+            // of a Visitor to return an error if it does not understand the data
+            DeEvent::Text(e) => match e.text {
+                Cow::Borrowed(s) => visitor.visit_borrowed_str(s),
+                Cow::Owned(s) => visitor.visit_string(s),
+            },
             DeEvent::Eof => Err(DeError::UnexpectedEof),
         }
     }

src/de/text.rs

@@ -32,7 +32,9 @@ use std::borrow::Cow;
 ///   deserializer;
 /// - sequences, tuples and tuple structs are deserialized using [`SimpleTypeDeserializer`]
 ///   (this is the difference): text content passed to the deserializer directly;
-/// - structs and maps returns [`DeError::ExpectedStart`];
+/// - structs and maps calls [`Visitor::visit_borrowed_str`] or [`Visitor::visit_string`],
+///   it is responsibility of the type to return an error if it do not able to process
+///   this data;
 /// - enums:
 ///   - the variant name is deserialized as `$text`;
 ///   - the content is deserialized using the same deserializer:
@@ -117,12 +119,15 @@ impl<'de> Deserializer<'de> for TextDeserializer<'de> {
         self,
         _name: &'static str,
         _fields: &'static [&'static str],
-        _visitor: V,
+        visitor: V,
     ) -> Result<V::Value, Self::Error>
     where
         V: Visitor<'de>,
     {
-        Err(DeError::ExpectedStart)
+        // Deserializer methods are only hints, if deserializer could not satisfy
+        // request, it should return the data that it has. It is responsibility
+        // of a Visitor to return an error if it does not understand the data
+        self.deserialize_str(visitor)
     }
 
     fn deserialize_enum<V>(

src/errors.rs

@@ -205,12 +205,6 @@ pub mod serialize {
         /// [`Event::Start`]: crate::events::Event::Start
         /// [`Event::End`]: crate::events::Event::End
         UnexpectedEof,
-        /// This error indicates that [`deserialize_struct`] was called, but there
-        /// is no any XML element in the input. That means that you try to deserialize
-        /// a struct not from an XML element.
-        ///
-        /// [`deserialize_struct`]: serde::de::Deserializer::deserialize_struct
-        ExpectedStart,
         /// An attempt to deserialize to a type, that is not supported by the XML
         /// store at current position, for example, attempt to deserialize `struct`
         /// from attribute or attempt to deserialize binary data.
@@ -245,7 +239,6 @@ pub mod serialize {
                     f.write_str(")`")
                 }
                 DeError::UnexpectedEof => write!(f, "Unexpected `Event::Eof`"),
-                DeError::ExpectedStart => write!(f, "Expecting `Event::Start`"),
                 DeError::Unsupported(s) => write!(f, "Unsupported operation: {}", s),
                 #[cfg(feature = "overlapped-lists")]
                 DeError::TooManyEvents(s) => write!(f, "Deserializer buffers {} events, limit exceeded", s),

tests/serde-de.rs

@@ -890,8 +890,14 @@ mod struct_ {
             match from_str::<Elements>(
                 "\nexcess text\t<root><float>42</float><string>answer</string></root>",
             ) {
-                Err(DeError::ExpectedStart) => {}
-                x => panic!("Expected `Err(ExpectedStart)`, but got `{:?}`", x),
+                Err(DeError::Custom(reason)) => assert_eq!(
+                    reason,
+                    "invalid type: string \"excess text\", expected struct Elements",
+                ),
+                x => panic!(
+                    r#"Expected `Err(Custom("invalid type: string \"excess text\", expected struct Elements"))`, but got `{:?}`"#,
+                    x
+                ),
             };
         }
 
@@ -901,8 +907,14 @@ mod struct_ {
             match from_str::<Elements>(
                 "<![CDATA[excess cdata]]><root><float>42</float><string>answer</string></root>",
             ) {
-                Err(DeError::ExpectedStart) => {}
-                x => panic!("Expected `Err(ExpectedStart)`, but got `{:?}`", x),
+                Err(DeError::Custom(reason)) => assert_eq!(
+                    reason,
+                    "invalid type: string \"excess cdata\", expected struct Elements",
+                ),
+                x => panic!(
+                    r#"Expected `Err(Custom("invalid type: string \"excess cdata\", expected struct Elements"))`, but got `{:?}`"#,
+                    x
+                ),
             };
         }