From 6b5d87869b1e8a3c022a96fd51fffa557ba83fb6 Mon Sep 17 00:00:00 2001
From: Michael Sproul <michael@sigmaprime.io>
Date: Mon, 12 Jan 2026 16:11:46 +1100
Subject: [PATCH] Compatible union tests

---
 Cargo.lock                                | 24 ++++++------
 testing/ef_tests/src/cases/ssz_generic.rs | 45 +++++++++++++++++++++++
 2 files changed, 57 insertions(+), 12 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 0ea1bdb011..3520d3d8be 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1953,7 +1953,7 @@ version = "3.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "fde0e0ec90c9dfb3b4b1a0891a7dcd0e2bffde2f7efed5fe7c9bb00e5bfb915e"
 dependencies = [
- "windows-sys 0.59.0",
+ "windows-sys 0.48.0",
 ]
 
 [[package]]
@@ -3119,7 +3119,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "39cab71617ae0d63f51a36d69f866391735b51691dbda63cf6f96d042b63efeb"
 dependencies = [
  "libc",
- "windows-sys 0.61.2",
+ "windows-sys 0.59.0",
 ]
 
 [[package]]
@@ -3284,7 +3284,7 @@ dependencies = [
 [[package]]
 name = "ethereum_ssz"
 version = "0.10.0"
-source = "git+https://github.com/sigp/ethereum_ssz?branch=progressive#952eb175cf463ec92d3abaf232e42fb72af7314e"
+source = "git+https://github.com/sigp/ethereum_ssz?branch=progressive#ed6332b0572f18bf285d2acdfc6932e1b9d274ef"
 dependencies = [
  "alloy-primitives",
  "arbitrary",
@@ -3300,7 +3300,7 @@ dependencies = [
 [[package]]
 name = "ethereum_ssz_derive"
 version = "0.10.0"
-source = "git+https://github.com/sigp/ethereum_ssz?branch=progressive#952eb175cf463ec92d3abaf232e42fb72af7314e"
+source = "git+https://github.com/sigp/ethereum_ssz?branch=progressive#ed6332b0572f18bf285d2acdfc6932e1b9d274ef"
 dependencies = [
  "darling 0.20.11",
  "proc-macro2",
@@ -4758,7 +4758,7 @@ checksum = "3640c1c38b8e4e43584d8df18be5fc6b0aa314ce6ebf51b53313d4306cca8e46"
 dependencies = [
  "hermit-abi 0.5.2",
  "libc",
- "windows-sys 0.61.2",
+ "windows-sys 0.59.0",
 ]
 
 [[package]]
@@ -6343,7 +6343,7 @@ version = "0.50.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7957b9740744892f114936ab4a57b3f487491bbeafaf8083688b16841a4240e5"
 dependencies = [
- "windows-sys 0.61.2",
+ "windows-sys 0.59.0",
 ]
 
 [[package]]
@@ -7263,7 +7263,7 @@ dependencies = [
  "once_cell",
  "socket2 0.6.1",
  "tracing",
- "windows-sys 0.60.2",
+ "windows-sys 0.59.0",
 ]
 
 [[package]]
@@ -7785,7 +7785,7 @@ dependencies = [
  "errno",
  "libc",
  "linux-raw-sys 0.11.0",
- "windows-sys 0.61.2",
+ "windows-sys 0.59.0",
 ]
 
 [[package]]
@@ -8872,7 +8872,7 @@ dependencies = [
  "getrandom 0.3.4",
  "once_cell",
  "rustix 1.1.2",
- "windows-sys 0.61.2",
+ "windows-sys 0.59.0",
 ]
 
 [[package]]
@@ -9445,7 +9445,7 @@ dependencies = [
 [[package]]
 name = "tree_hash"
 version = "0.12.0"
-source = "git+https://github.com/sigp/tree_hash?branch=progressive#7400510546840a3985474380d934d33f9ba0d417"
+source = "git+https://github.com/sigp/tree_hash?branch=progressive#2fd80712e4d85e5f61dc574d8f5837a5c9b355b8"
 dependencies = [
  "alloy-primitives",
  "ethereum_hashing",
@@ -9457,7 +9457,7 @@ dependencies = [
 [[package]]
 name = "tree_hash_derive"
 version = "0.12.0"
-source = "git+https://github.com/sigp/tree_hash?branch=progressive#7400510546840a3985474380d934d33f9ba0d417"
+source = "git+https://github.com/sigp/tree_hash?branch=progressive#2fd80712e4d85e5f61dc574d8f5837a5c9b355b8"
 dependencies = [
  "darling 0.21.3",
  "proc-macro2",
@@ -10206,7 +10206,7 @@ version = "0.1.11"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c2a7b1c03c876122aa43f3020e6c3c3ee5c05081c9a00739faf7503aeba10d22"
 dependencies = [
- "windows-sys 0.61.2",
+ "windows-sys 0.48.0",
 ]
 
 [[package]]
diff --git a/testing/ef_tests/src/cases/ssz_generic.rs b/testing/ef_tests/src/cases/ssz_generic.rs
index ca42ac1d1d..bd1567fbfc 100644
--- a/testing/ef_tests/src/cases/ssz_generic.rs
+++ b/testing/ef_tests/src/cases/ssz_generic.rs
@@ -123,6 +123,9 @@ macro_rules! type_dispatch {
             "ProgressiveVarTestStruct" => type_dispatch!($function, ($($arg),*), $base_ty, <$($param_ty,)* ProgressiveVarTestStruct>, $($rest)*),
             "ProgressiveComplexTestStruct" => type_dispatch!($function, ($($arg),*), $base_ty, <$($param_ty,)* ProgressiveComplexTestStruct>, $($rest)*),
             "ProgressiveTestStruct" => type_dispatch!($function, ($($arg),*), $base_ty, <$($param_ty,)* ProgressiveTestStruct>, $($rest)*),
+            "CompatibleUnionA" => type_dispatch!($function, ($($arg),*), $base_ty, <$($param_ty,)* CompatibleUnionA>, $($rest)*),
+            "CompatibleUnionBC" => type_dispatch!($function, ($($arg),*), $base_ty, <$($param_ty,)* CompatibleUnionBC>, $($rest)*),
+            "CompatibleUnionABCA" => type_dispatch!($function, ($($arg),*), $base_ty, <$($param_ty,)* CompatibleUnionABCA>, $($rest)*),
             _ => Err(Error::FailedToParseTest(format!("unsupported: {}", $value))),
         }
     };
@@ -422,6 +425,48 @@ struct ProgressiveComplexTestStruct {
     H: ProgressiveList<ProgressiveVarTestStruct>,
 }
 
+#[derive(Debug, Clone, PartialEq, Decode, Encode, TreeHash, Deserialize)]
+#[ssz(enum_behaviour = "compatible_union")]
+#[tree_hash(enum_behaviour = "compatible_union")]
+#[context_deserialize(ForkName)]
+enum CompatibleUnionA {
+    #[ssz(selector = "1")]
+    #[tree_hash(selector = "1")]
+    ProgressiveSingleFieldContainerTestStruct(ProgressiveSingleFieldContainerTestStruct),
+}
+
+#[derive(Debug, Clone, PartialEq, Decode, Encode, TreeHash, Deserialize)]
+#[ssz(enum_behaviour = "compatible_union")]
+#[tree_hash(enum_behaviour = "compatible_union")]
+#[context_deserialize(ForkName)]
+enum CompatibleUnionBC {
+    #[ssz(selector = "2")]
+    #[tree_hash(selector = "2")]
+    ProgressiveSingleListContainerTestStruct(ProgressiveSingleListContainerTestStruct),
+    #[ssz(selector = "3")]
+    #[tree_hash(selector = "3")]
+    ProgressiveVarTestStruct(ProgressiveVarTestStruct),
+}
+
+#[derive(Debug, Clone, PartialEq, Decode, Encode, TreeHash, Deserialize)]
+#[ssz(enum_behaviour = "compatible_union")]
+#[tree_hash(enum_behaviour = "compatible_union")]
+#[context_deserialize(ForkName)]
+enum CompatibleUnionABCA {
+    #[ssz(selector = "1")]
+    #[tree_hash(selector = "1")]
+    A1(ProgressiveSingleFieldContainerTestStruct),
+    #[ssz(selector = "2")]
+    #[tree_hash(selector = "2")]
+    B1(ProgressiveSingleListContainerTestStruct),
+    #[ssz(selector = "3")]
+    #[tree_hash(selector = "3")]
+    C1(ProgressiveVarTestStruct),
+    #[ssz(selector = "4")]
+    #[tree_hash(selector = "4")]
+    A2(ProgressiveSingleFieldContainerTestStruct),
+}
+
 fn byte_list_from_hex_str<'de, D, N: Unsigned>(
     deserializer: D,
 ) -> Result<VariableList<u8, N>, D::Error>