Depend on both crates individually

Cargo.lock

@@ -52,9 +52,6 @@ name = "arbitrary"
 version = "1.0.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "577b08a4acd7b99869f863c50011b01eb73424ccc798ecd996f2e24817adfca7"
-dependencies = [
- "derive_arbitrary",
-]
 
 [[package]]
 name = "arrayvec"
@@ -157,6 +154,7 @@ name = "cfg"
 version = "0.0.0"
 dependencies = [
  "arbitrary",
+ "derive_arbitrary",
  "expect-test",
  "mbe",
  "oorandom",

crates/cfg/Cargo.toml

@@ -17,5 +17,9 @@ tt = { path = "../tt", version = "0.0.0" }
 mbe = { path = "../mbe" }
 syntax = { path = "../syntax" }
 expect-test = "1.1"
-arbitrary = { version = "1", features = ["derive"] }
 oorandom = "11"
+# We depend on both individually instead of using `features = ["derive"]` to microoptimize the
+# build graph: if the feature was enabled, syn would be built early on in the graph if `smolstr`
+# supports `arbitrary`. This way, we avoid feature unification.
+arbitrary = "1"
+derive_arbitrary = "1"

crates/cfg/src/cfg_expr.rs

@@ -50,7 +50,7 @@ impl fmt::Display for CfgAtom {
 }
 
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
-#[cfg_attr(test, derive(arbitrary::Arbitrary))]
+#[cfg_attr(test, derive(derive_arbitrary::Arbitrary))]
 pub enum CfgExpr {
     Invalid,
     Atom(CfgAtom),