From a74e9e5eabf74a16ab10947eff37b29f09c96d1a Mon Sep 17 00:00:00 2001
From: Michael Sproul <michael@sigmaprime.io>
Date: Tue, 18 Aug 2026 15:12:43 +1000
Subject: [PATCH 1/2] Unbreak trybuild tests on my machine

---
 .cargo/config.toml | 4 ++++
 1 file changed, 4 insertions(+)
 create mode 100644 .cargo/config.toml

diff --git a/.cargo/config.toml b/.cargo/config.toml
new file mode 100644
index 0000000..e6aa557
--- /dev/null
+++ b/.cargo/config.toml
@@ -0,0 +1,4 @@
+[term]
+# Set `color` to `auto` in case the user has set it to `always`, which would
+# cause divergence in compiler output and break the trybuild tests.
+color = "auto"

From e40e0ec1e869ea618973a62977594fa81964839f Mon Sep 17 00:00:00 2001
From: Michael Sproul <michael@sigmaprime.io>
Date: Tue, 18 Aug 2026 15:28:41 +1000
Subject: [PATCH 2/2] Duplicate selector test case

---
 .../tests/compile_fail/duplicate_variant_selector.rs  | 11 +++++++++++
 .../compile_fail/duplicate_variant_selector.stderr    |  7 +++++++
 2 files changed, 18 insertions(+)
 create mode 100644 tree_hash/tests/compile_fail/duplicate_variant_selector.rs
 create mode 100644 tree_hash/tests/compile_fail/duplicate_variant_selector.stderr

diff --git a/tree_hash/tests/compile_fail/duplicate_variant_selector.rs b/tree_hash/tests/compile_fail/duplicate_variant_selector.rs
new file mode 100644
index 0000000..3a0e738
--- /dev/null
+++ b/tree_hash/tests/compile_fail/duplicate_variant_selector.rs
@@ -0,0 +1,11 @@
+//! More than one selector in a variant-level `tree_hash` attribute must be rejected.
+use tree_hash_derive::TreeHash;
+
+#[derive(TreeHash)]
+#[tree_hash(enum_behaviour = "compatible_union")]
+enum Foo {
+    #[tree_hash(selector = "1", selector = "2")]
+    A(u8),
+}
+
+fn main() {}
diff --git a/tree_hash/tests/compile_fail/duplicate_variant_selector.stderr b/tree_hash/tests/compile_fail/duplicate_variant_selector.stderr
new file mode 100644
index 0000000..4a5470c
--- /dev/null
+++ b/tree_hash/tests/compile_fail/duplicate_variant_selector.stderr
@@ -0,0 +1,7 @@
+error: proc-macro derive panicked
+ --> tests/compile_fail/duplicate_variant_selector.rs:4:10
+  |
+4 | #[derive(TreeHash)]
+  |          ^^^^^^^^
+  |
+  = help: message: failed to parse variant attribute for "A": Duplicate field `selector`; note that `selector` must be an integer in 1..=127