Simplify and document EvenAsOpaque with new usage

frozen-abi/Cargo.toml

@@ -38,6 +38,7 @@ cc = { workspace = true, features = ["jobserver", "parallel"] }
 
 [target.'cfg(not(target_os = "solana"))'.dev-dependencies]
 solana-logger = { workspace = true }
+bitflags = { workspace = true }
 
 [build-dependencies]
 rustc_version = { workspace = true }

frozen-abi/src/abi_digester.rs

@@ -17,7 +17,7 @@ pub struct AbiDigester {
     data_types: std::rc::Rc<std::cell::RefCell<Vec<String>>>,
     depth: usize,
     for_enum: bool,
-    opaque_scope: Option<String>,
+    opaque_type_matcher: Option<String>,
 }
 
 pub type DigestResult = Result<AbiDigester, DigestError>;
@@ -70,7 +70,7 @@ impl AbiDigester {
             data_types: std::rc::Rc::new(std::cell::RefCell::new(vec![])),
             for_enum: false,
             depth: 0,
-            opaque_scope: None,
+            opaque_type_matcher: None,
         }
     }
 
@@ -81,7 +81,7 @@ impl AbiDigester {
             data_types: self.data_types.clone(),
             depth: self.depth,
             for_enum: false,
-            opaque_scope: self.opaque_scope.clone(),
+            opaque_type_matcher: self.opaque_type_matcher.clone(),
         }
     }
 
@@ -90,7 +90,7 @@ impl AbiDigester {
             data_types: self.data_types.clone(),
             depth: self.depth,
             for_enum: false,
-            opaque_scope: Some(scope.to_owned()),
+            opaque_type_matcher: Some(scope.to_owned()),
         }
     }
 
@@ -103,7 +103,7 @@ impl AbiDigester {
             data_types: self.data_types.clone(),
             depth,
             for_enum: false,
-            opaque_scope: self.opaque_scope.clone(),
+            opaque_type_matcher: self.opaque_type_matcher.clone(),
         })
     }
 
@@ -116,15 +116,15 @@ impl AbiDigester {
             data_types: self.data_types.clone(),
             depth,
             for_enum: true,
-            opaque_scope: self.opaque_scope.clone(),
+            opaque_type_matcher: self.opaque_type_matcher.clone(),
         })
     }
 
     pub fn digest_data<T: ?Sized + Serialize>(&mut self, value: &T) -> DigestResult {
         let type_name = normalize_type_name(type_name::<T>());
         if type_name.ends_with("__SerializeWith")
-            || (self.opaque_scope.is_some()
-                && type_name.contains(self.opaque_scope.as_ref().unwrap()))
+            || (self.opaque_type_matcher.is_some()
+                && type_name.contains(self.opaque_type_matcher.as_ref().unwrap()))
         {
             // we can't use the AbiEnumVisitor trait for these cases.
             value.serialize(self.create_new())
@@ -661,6 +661,35 @@ mod tests {
     #[frozen_abi(digest = "9PMdHRb49BpkywrmPoJyZWMsEmf5E1xgmsFGkGmea5RW")]
     type TestBitVec = bv::BitVec<u64>;
 
+    mod bitflags {
+        use crate::abi_example::{AbiExample, EvenAsOpaque, IgnoreAsHelper};
+
+        bitflags::bitflags! {
+            #[frozen_abi(digest = "HYjQ8oiYirTnQoLeRHbq66i8VYfcxPA4QTT3gdUQBgyV")]
+            #[derive(Serialize, Deserialize)]
+            struct TestFlags: u8 {
+                const TestBit = 0b0000_0001;
+            }
+        }
+
+        impl AbiExample for TestFlags {
+            fn example() -> Self {
+                Self::empty()
+            }
+        }
+
+        impl IgnoreAsHelper for TestFlags {}
+        // This (EvenAsOpaque) marker trait is needed for bitflags-generated types because we can't
+        // impl AbiExample for its
+        // private type:
+        // thread '...TestFlags_frozen_abi...' panicked at ...:
+        //   derive or implement AbiExample/AbiEnumVisitor for
+        //   solana_frozen_abi::abi_digester::tests::_::InternalBitFlags
+        impl EvenAsOpaque for TestFlags {
+            const TYPE_NAME_MATCHER: &'static str = "::_::InternalBitFlags";
+        }
+    }
+
     mod skip_should_be_same {
         #[frozen_abi(digest = "4LbuvQLX78XPbm4hqqZcHFHpseDJcw4qZL9EUZXSi2Ss")]
         #[derive(Serialize, AbiExample)]

frozen-abi/src/abi_example.rs

@@ -219,7 +219,14 @@ impl<T: BlockType> AbiExample for BitVec<T> {
 }
 
 impl<T: BlockType> IgnoreAsHelper for BitVec<T> {}
-impl<T: BlockType> EvenAsOpaque for BitVec<T> {}
+// This (EvenAsOpaque) marker trait is needed for BitVec because we can't impl AbiExample for its
+// private type:
+// thread '...TestBitVec_frozen_abi...' panicked at ...:
+//   derive or implement AbiExample/AbiEnumVisitor for
+//   bv::bit_vec::inner::Inner<u64>
+impl<T: BlockType> EvenAsOpaque for BitVec<T> {
+    const TYPE_NAME_MATCHER: &'static str = "bv::bit_vec::inner::";
+}
 
 pub(crate) fn normalize_type_name(type_name: &str) -> String {
     type_name.chars().filter(|c| *c != '&').collect()
@@ -494,14 +501,21 @@ impl AbiExample for IpAddr {
     }
 }
 
-// This is a control flow indirection needed for digesting all variants of an enum
+// This is a control flow indirection needed for digesting all variants of an enum.
+//
+// All of types (including non-enums) will be processed by this trait, albeit the
+// name of this trait.
+// User-defined enums usually just need to impl this with namesake derive macro (AbiEnumVisitor).
+//
+// Note that sometimes this indirection doesn't work for various reasons. For that end, there are
+// hacks with marker traits (IgnoreAsHelper/EvenAsOpaque).
 pub trait AbiEnumVisitor: Serialize {
     fn visit_for_abi(&self, digester: &mut AbiDigester) -> DigestResult;
 }
 
 pub trait IgnoreAsHelper {}
 pub trait EvenAsOpaque {
-    const SCOPE: Option<&'static str> = None;
+    const TYPE_NAME_MATCHER: &'static str;
 }
 
 impl<T: Serialize + ?Sized> AbiEnumVisitor for T {
@@ -550,16 +564,12 @@ impl<T: Serialize + IgnoreAsHelper> AbiEnumVisitor for &T {
 impl<T: Serialize + IgnoreAsHelper + EvenAsOpaque> AbiEnumVisitor for &T {
     default fn visit_for_abi(&self, digester: &mut AbiDigester) -> DigestResult {
         let type_name = type_name::<T>();
-        let scope = if let Some(scope) = T::SCOPE {
-            scope
-        } else {
-            type_name.split("::").next().unwrap()
-        };
+        let matcher = T::TYPE_NAME_MATCHER;
         info!(
-            "AbiEnumVisitor for (EvenAsOpaque): {}: scope: {}",
-            type_name, scope
+            "AbiEnumVisitor for (EvenAsOpaque): {}: matcher: {}",
+            type_name, matcher
         );
-        self.serialize(digester.create_new_opaque(scope))
+        self.serialize(digester.create_new_opaque(matcher))
             .map_err(DigestError::wrap_by_type::<T>)
     }
 }

sdk/src/packet.rs

@@ -57,7 +57,7 @@ impl ::solana_frozen_abi::abi_example::IgnoreAsHelper for PacketFlags {}
 
 #[cfg(RUSTC_WITH_SPECIALIZATION)]
 impl ::solana_frozen_abi::abi_example::EvenAsOpaque for PacketFlags {
-    const SCOPE: Option<&'static str> = Some("InternalBitFlags");
+    const TYPE_NAME_MATCHER: &'static str = "::_::InternalBitFlags";
 }
 
 // serde_as is used as a work around because array isn't supported by serde