Add OptionExt with is_none_or to rustc_data_structures

Author: WaffleLapkin

compiler/rustc_data_structures/src/lib.rs

@@ -94,8 +94,10 @@ pub mod work_queue;
 
 mod atomic_ref;
 mod hashes;
+mod option_ext;
 
 pub use atomic_ref::AtomicRef;
+pub use option_ext::OptionExt;
 
 #[inline(never)]
 #[cold]

compiler/rustc_data_structures/src/option_ext.rs

@@ -0,0 +1,18 @@
+/// Extension for [`Option`] that adds handy methods missing from it.
+pub trait OptionExt {
+    type T;
+
+    fn is_none_or(self, f: impl FnOnce(Self::T) -> bool) -> bool;
+}
+
+impl<T> OptionExt for Option<T> {
+    type T = T;
+
+    /// Returns `true` is `self` is `None` or the value inside matches a predicate `f`.
+    fn is_none_or(self, f: impl FnOnce(T) -> bool) -> bool {
+        match self {
+            None => true,
+            Some(x) => f(x),
+        }
+    }
+}