From 6e800ff826f0240838ae11a5ad1f723c6e242a90 Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Sun, 24 Jan 2021 23:04:01 -0800
Subject: [PATCH] Test exhaustiveness of type match in collect_lifetimes

---
 serde_derive/src/internals/attr.rs | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/serde_derive/src/internals/attr.rs b/serde_derive/src/internals/attr.rs
index 918d47bf..e53f5891 100644
--- a/serde_derive/src/internals/attr.rs
+++ b/serde_derive/src/internals/attr.rs
@@ -1909,8 +1909,12 @@ fn collect_lifetimes(ty: &syn::Type, out: &mut BTreeSet<syn::Lifetime>) {
         | syn::Type::TraitObject(_)
         | syn::Type::ImplTrait(_)
         | syn::Type::Infer(_)
-        | syn::Type::Verbatim(_)
-        | _ => {}
+        | syn::Type::Verbatim(_) => {}
+
+        #[cfg(test)]
+        syn::Type::__TestExhaustive(_) => unimplemented!(),
+        #[cfg(not(test))]
+        _ => {}
     }
 }