Patch serde content detection hack (#580)

Author: juntyr

fuzz/fuzz_targets/bench/lib.rs

@@ -22,7 +22,7 @@ const ARRAY_UNINIT_LEN: usize = usize::MAX;
 
 const FLATTEN_CONFLICT_MSG: &str = "ron::fuzz::FlattenFieldConflict";
 
-pub fn roundtrip_arbitrary_typed_ron_or_panic(data: &[u8]) -> Option<TypedSerdeData> {
+pub fn roundtrip_arbitrary_typed_ron_or_panic(data: &[u8]) -> Option<TypedSerdeData<'_>> {
     if let Ok(typed_value) = TypedSerdeData::arbitrary(&mut Unstructured::new(data)) {
         let options = ron::Options::default().with_recursion_limit(RECURSION_LIMIT);
 

src/de/mod.rs

@@ -28,9 +28,6 @@ mod tag;
 mod tests;
 mod value;
 
-const SERDE_CONTENT_CANARY: &str = "serde::__private::de::content::Content";
-const SERDE_TAG_KEY_CANARY: &str = "serde::__private::de::content::TagOrContent";
-
 /// The RON deserializer.
 ///
 /// If you just want to simply deserialize a value,
@@ -179,8 +176,8 @@ impl<'de> Deserializer<'de> {
     {
         // HACK: switch to JSON enum semantics for JSON content
         // Robust impl blocked on https://github.com/serde-rs/serde/pull/2420
-        let is_serde_content = core::any::type_name::<V::Value>() == SERDE_CONTENT_CANARY
-            || core::any::type_name::<V::Value>() == SERDE_TAG_KEY_CANARY;
+        let is_serde_content =
+            is_serde_content::<V::Value>() || is_serde_tag_or_content::<V::Value>();
 
         let old_serde_content_newtype = self.serde_content_newtype;
         self.serde_content_newtype = false;
@@ -857,8 +854,7 @@ impl<'de, 'a> de::MapAccess<'de> for CommaSeparated<'a, 'de> {
         K: DeserializeSeed<'de>,
     {
         if self.has_element()? {
-            self.inside_internally_tagged_enum =
-                core::any::type_name::<K::Value>() == SERDE_TAG_KEY_CANARY;
+            self.inside_internally_tagged_enum = is_serde_tag_or_content::<K::Value>();
 
             match self.terminator {
                 Terminator::Struct => guard_recursion! { self.de =>
@@ -883,9 +879,7 @@ impl<'de, 'a> de::MapAccess<'de> for CommaSeparated<'a, 'de> {
         if self.de.parser.consume_char(':') {
             self.de.parser.skip_ws()?;
 
-            let res = if self.inside_internally_tagged_enum
-                && core::any::type_name::<V::Value>() != SERDE_CONTENT_CANARY
-            {
+            let res = if self.inside_internally_tagged_enum && !is_serde_content::<V::Value>() {
                 guard_recursion! { self.de =>
                     seed.deserialize(&mut tag::Deserializer::new(&mut *self.de))?
                 }
@@ -1052,3 +1046,19 @@ impl<'de, 'a> de::MapAccess<'de> for SerdeEnumContent<'a, 'de> {
         result
     }
 }
+
+// ensure that these are the same as in the 449_tagged_enum test
+fn is_serde_content<T>() -> bool {
+    matches!(
+        core::any::type_name::<T>(),
+        "serde::__private::de::content::Content" | "serde::__private::de::content::Content<'_>"
+    )
+}
+
+fn is_serde_tag_or_content<T>() -> bool {
+    matches!(
+        core::any::type_name::<T>(),
+        "serde::__private::de::content::TagOrContent"
+            | "serde::__private::de::content::TagOrContent<'_>"
+    )
+}

tests/449_tagged_enum.rs

@@ -43,16 +43,29 @@ enum OuterEnumUntagged {
 
 #[test]
 fn test_serde_content_hack() {
-    assert_eq!(
+    assert!(matches!(
         std::any::type_name::<serde::__private::de::Content>(),
-        "serde::__private::de::content::Content"
-    );
+        "serde::__private::de::content::Content" | "serde::__private::de::content::Content<'_>"
+    ));
 }
 
 #[test]
 fn test_serde_internally_tagged_hack() {
-    const SERDE_CONTENT_CANARY: &str = "serde::__private::de::content::Content";
-    const SERDE_TAG_KEY_CANARY: &str = "serde::__private::de::content::TagOrContent";
+    // ensure that these are the same as in ron::de module
+    fn is_serde_content<T>() -> bool {
+        matches!(
+            core::any::type_name::<T>(),
+            "serde::__private::de::content::Content" | "serde::__private::de::content::Content<'_>"
+        )
+    }
+
+    fn is_serde_tag_or_content<T>() -> bool {
+        matches!(
+            core::any::type_name::<T>(),
+            "serde::__private::de::content::TagOrContent"
+                | "serde::__private::de::content::TagOrContent<'_>"
+        )
+    }
 
     struct Deserializer {
         tag_key: Option<String>,
@@ -87,7 +100,7 @@ fn test_serde_internally_tagged_hack() {
         where
             K: serde::de::DeserializeSeed<'de>,
         {
-            assert_eq!(std::any::type_name::<K::Value>(), SERDE_TAG_KEY_CANARY);
+            assert!(is_serde_tag_or_content::<K::Value>());
 
             if let Some(tag_key) = self.tag_key.take() {
                 return seed
@@ -109,11 +122,11 @@ fn test_serde_internally_tagged_hack() {
             V: serde::de::DeserializeSeed<'de>,
         {
             if self.field_key.is_some() {
-                assert_ne!(std::any::type_name::<V::Value>(), SERDE_CONTENT_CANARY);
+                assert!(!is_serde_content::<V::Value>());
                 return seed.deserialize(serde::de::value::StrDeserializer::new(&self.tag_value));
             }
 
-            assert_eq!(std::any::type_name::<V::Value>(), SERDE_CONTENT_CANARY);
+            assert!(is_serde_content::<V::Value>());
 
             seed.deserialize(serde::de::value::I32Deserializer::new(self.field_value))
         }