Add unstable may_dangle feature

Cargo.toml

@@ -52,6 +52,7 @@ harness = false
 [features]
 default = ["std"]
 std = []
+may_dangle = []
 
 [profile.bench]
 debug = true

src/arrayvec.rs

@@ -46,6 +46,16 @@ pub struct ArrayVec<T, const CAP: usize> {
     xs: [MaybeUninit<T>; CAP],
 }
 
+#[cfg(feature = "may_dangle")]
+unsafe impl<#[may_dangle] T, const CAP: usize> Drop for ArrayVec<T, CAP> {
+    fn drop(&mut self) {
+        self.clear();
+
+        // MaybeUninit inhibits array's drop
+    }
+}
+
+#[cfg(not(feature = "may_dangle"))]
 impl<T, const CAP: usize> Drop for ArrayVec<T, CAP> {
     fn drop(&mut self) {
         self.clear();

src/lib.rs

@@ -14,13 +14,20 @@
 //! - `zeroize`
 //!   - Optional
 //!   - Implement `Zeroize` for ArrayVec and ArrayString
+//! 
+//! - `may_dangle`
+//!   - Optional and unstable
+//!   - Requires nightly toolchain
+//!   - Makes compiler less strict about storing references with a lifetime in ArrayVec,
+//!     see [Rustonomicon](https://doc.rust-lang.org/1.42.0/nomicon/dropck.html#an-escape-hatch).
 //!
 //! ## Rust Version
 //!
 //! This version of arrayvec requires Rust 1.51 or later.
 //!
 #![doc(html_root_url="https://docs.rs/arrayvec/0.7/")]
 #![cfg_attr(not(feature="std"), no_std)]
+#![cfg_attr(feature = "may_dangle", feature(dropck_eyepatch))]
 
 #[cfg(feature="serde")]
 extern crate serde;