Allow unsizing pattern types with pointer base

Author: oli-obk

core/src/lib.rs

@@ -116,6 +116,7 @@
 #![feature(link_cfg)]
 #![feature(offset_of_enum)]
 #![feature(panic_internals)]
+#![feature(pattern_type_macro)]
 #![feature(ptr_alignment_type)]
 #![feature(ptr_metadata)]
 #![feature(set_ptr_value)]
@@ -171,6 +172,7 @@
 #![feature(never_type)]
 #![feature(no_core)]
 #![feature(optimize_attribute)]
+#![feature(pattern_types)]
 #![feature(prelude_import)]
 #![feature(reborrow)]
 #![feature(repr_simd)]

core/src/pat.rs

@@ -1,5 +1,8 @@
 //! Helper module for exporting the `pattern_type` macro
 
+use crate::marker::{Freeze, PointeeSized, Unsize};
+use crate::ops::{CoerceUnsized, DispatchFromDyn};
+
 /// Creates a pattern type.
 /// ```ignore (cannot test this from within core yet)
 /// type Positive = std::pat::pattern_type!(i32 is 1..);
@@ -73,3 +76,16 @@ impl const RangePattern for char {
         }
     }
 }
+
+impl<T: PointeeSized, U: PointeeSized> CoerceUnsized<pattern_type!(*const U is !null)> for pattern_type!(*const T is !null) where
+    T: Unsize<U>
+{
+}
+
+impl<T: DispatchFromDyn<U>, U> DispatchFromDyn<pattern_type!(U is !null)> for pattern_type!(T is !null) {}
+
+impl<T: PointeeSized> Unpin for pattern_type!(*const T is !null) {}
+
+unsafe impl<T: PointeeSized> Freeze for pattern_type!(*const T is !null) {}
+
+unsafe impl<T: PointeeSized> Freeze for pattern_type!(*mut T is !null) {}