We need at least rustc 1.28 to use repr transparent.

Cargo.toml

@@ -11,6 +11,10 @@ categories = ["data-structures", "no-std"]
 [dependencies]
 # not even std!
 
+[features]
+default = []
+rustc_28 = []
+
 [badges]
 appveyor = { repository = "Lokathor/tinyvec" }
 travis-ci = { repository = "Lokathor/tinyvec" }

src/lib.rs

@@ -23,7 +23,7 @@ enum Payload<T: Default> {
 /// A `TinyVec<T>` is like a `Vec<T>`, but it will store up to 8 elements
 /// "inline" on the stack before transitioning into being a normal `Vec<T>`.
 #[derive(Debug, Clone)]
-#[repr(transparent)]
+#[cfg_attr(feature = "rustc_28", repr(transparent))]
 pub struct TinyVec<T: Default>(Payload<T>);
 
 // TODO: impl a better Debug