diff --git a/src/librustdoc/clean/types.rs b/src/librustdoc/clean/types.rs
index 38791fcea54..b43bf88c2af 100644
--- a/src/librustdoc/clean/types.rs
+++ b/src/librustdoc/clean/types.rs
@@ -1226,6 +1226,7 @@ crate enum Type {
     BareFunction(Box<BareFunctionDecl>),
     Tuple(Vec<Type>),
     Slice(Box<Type>),
+    /// The `String` field is about the size or the constant representing the array's length.
     Array(Box<Type>, String),
     Never,
     RawPointer(Mutability, Box<Type>),