Move guard macro into guard module

deptypes/Cargo.toml

@@ -25,4 +25,5 @@ default = ["std"]
 std = []
 never = []
 trusted_len = []
-nightly = ["never", "trusted_len"]
+super_let = []
+nightly = ["never", "trusted_len", "super_let"]

deptypes/src/guard.rs

@@ -0,0 +1,20 @@
+pub use generativity::*;
+
+#[cfg(feature = "super_let")]
+#[cfg_attr(docsrs, doc(cfg(feature = "super_let")))]
+#[macro_export]
+/// Create and return a [`generativity::Guard`] with a unique brand.
+///
+/// This macro mirrors [`make_guard!`] but produces the guard directly instead
+/// of binding it to a user-provided identifier. Because it relies on the
+/// unstable `super_let` language feature, it is only available when the
+/// crate's `"super_let"` feature is enabled (or through the `"nightly"`
+/// feature, which enables `"super_let"`).
+macro_rules! guard {
+    () => {{
+        super let branded_place = unsafe { $crate::guard::Id::new() };
+        #[allow(unused)]
+        let lifetime_brand = unsafe { $crate::guard::LifetimeBrand::new(&branded_place) };
+        unsafe { $crate::guard::Guard::new(branded_place) }
+    }};
+}

deptypes/src/lib.rs

@@ -2,6 +2,8 @@
 
 #![cfg_attr(feature = "never", feature(never_type))]
 #![cfg_attr(feature = "trusted_len", feature(trusted_len))]
+#![cfg_attr(feature = "super_let", feature(super_let))]
+#![cfg_attr(docsrs, feature(doc_cfg))]
 
 #[cfg(feature = "std")]
 extern crate alloc;
@@ -17,8 +19,13 @@ pub mod newtype;
 #[macro_use]
 pub mod zst;
 
-pub use generativity as guard;
-pub use generativity::make_guard as make_guard;
+pub mod guard;
+pub use crate::guard::make_guard as make_guard;
+
+#[cfg(feature = "super_let")]
+#[cfg_attr(docsrs, doc(cfg(feature = "super_let")))]
+#[doc(inline)]
+pub use crate::guard::guard as g;
 
 #[macro_use]
 pub mod type_eq;