From 8e8fd02b272bf8ca8e4c8f4d20552ca26a468a80 Mon Sep 17 00:00:00 2001
From: clubby789 <jamie@hill-daniel.co.uk>
Date: Thu, 27 Oct 2022 13:40:45 +0100
Subject: [PATCH] Specialize PartialEq for Option<num::NonZero*> and
 Option<ptr::NonNull>

---
 library/core/src/option.rs            | 68 ++++++++++++++++++++++++++-
 src/test/codegen/option-nonzero-eq.rs | 34 ++++++++++++++
 2 files changed, 101 insertions(+), 1 deletion(-)
 create mode 100644 src/test/codegen/option-nonzero-eq.rs

diff --git a/library/core/src/option.rs b/library/core/src/option.rs
index a81dbc6924f..e462f840fda 100644
--- a/library/core/src/option.rs
+++ b/library/core/src/option.rs
@@ -512,7 +512,7 @@
 };
 
 /// The `Option` type. See [the module level documentation](self) for more.
-#[derive(Copy, PartialEq, PartialOrd, Eq, Ord, Debug, Hash)]
+#[derive(Copy, PartialOrd, Eq, Ord, Debug, Hash)]
 #[rustc_diagnostic_item = "Option"]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub enum Option<T> {
@@ -2035,6 +2035,72 @@ fn from(o: &'a mut Option<T>) -> Option<&'a mut T> {
     }
 }
 
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T> crate::marker::StructuralPartialEq for Option<T> {}
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T: PartialEq> PartialEq for Option<T> {
+    #[inline]
+    fn eq(&self, other: &Self) -> bool {
+        SpecOptionPartialEq::eq(self, other)
+    }
+}
+
+#[unstable(feature = "spec_option_partial_eq", issue = "none")]
+#[doc(hidden)]
+pub trait SpecOptionPartialEq: Sized {
+    fn eq(l: &Option<Self>, other: &Option<Self>) -> bool;
+}
+
+#[unstable(feature = "spec_option_partial_eq", issue = "none")]
+impl<T: PartialEq> SpecOptionPartialEq for T {
+    #[inline]
+    default fn eq(l: &Option<T>, r: &Option<T>) -> bool {
+        match (l, r) {
+            (Some(l), Some(r)) => *l == *r,
+            (None, None) => true,
+            _ => false,
+        }
+    }
+}
+
+macro_rules! non_zero_option {
+    ( $( #[$stability: meta] $NZ:ty; )+ ) => {
+        $(
+            #[$stability]
+            impl SpecOptionPartialEq for $NZ {
+                #[inline]
+                fn eq(l: &Option<Self>, r: &Option<Self>) -> bool {
+                    l.map(Self::get).unwrap_or(0) == r.map(Self::get).unwrap_or(0)
+                }
+            }
+        )+
+    };
+}
+
+non_zero_option! {
+    #[stable(feature = "nonzero", since = "1.28.0")] crate::num::NonZeroU8;
+    #[stable(feature = "nonzero", since = "1.28.0")] crate::num::NonZeroU16;
+    #[stable(feature = "nonzero", since = "1.28.0")] crate::num::NonZeroU32;
+    #[stable(feature = "nonzero", since = "1.28.0")] crate::num::NonZeroU64;
+    #[stable(feature = "nonzero", since = "1.28.0")] crate::num::NonZeroU128;
+    #[stable(feature = "nonzero", since = "1.28.0")] crate::num::NonZeroUsize;
+    #[stable(feature = "signed_nonzero", since = "1.34.0")] crate::num::NonZeroI8;
+    #[stable(feature = "signed_nonzero", since = "1.34.0")] crate::num::NonZeroI16;
+    #[stable(feature = "signed_nonzero", since = "1.34.0")] crate::num::NonZeroI32;
+    #[stable(feature = "signed_nonzero", since = "1.34.0")] crate::num::NonZeroI64;
+    #[stable(feature = "signed_nonzero", since = "1.34.0")] crate::num::NonZeroI128;
+    #[stable(feature = "signed_nonzero", since = "1.34.0")] crate::num::NonZeroIsize;
+}
+
+#[stable(feature = "nonnull", since = "1.25.0")]
+impl<T> SpecOptionPartialEq for crate::ptr::NonNull<T> {
+    #[inline]
+    fn eq(l: &Option<Self>, r: &Option<Self>) -> bool {
+        l.map(Self::as_ptr).unwrap_or_else(|| crate::ptr::null_mut())
+            == r.map(Self::as_ptr).unwrap_or_else(|| crate::ptr::null_mut())
+    }
+}
+
 /////////////////////////////////////////////////////////////////////////////
 // The Option Iterators
 /////////////////////////////////////////////////////////////////////////////
diff --git a/src/test/codegen/option-nonzero-eq.rs b/src/test/codegen/option-nonzero-eq.rs
new file mode 100644
index 00000000000..598dcc19b49
--- /dev/null
+++ b/src/test/codegen/option-nonzero-eq.rs
@@ -0,0 +1,34 @@
+// compile-flags: -O -Zmerge-functions=disabled
+
+#![crate_type = "lib"]
+
+extern crate core;
+use core::num::{NonZeroU32, NonZeroI64};
+use core::ptr::NonNull;
+
+// CHECK-lABEL: @non_zero_eq
+#[no_mangle]
+pub fn non_zero_eq(l: Option<NonZeroU32>, r: Option<NonZeroU32>) -> bool {
+    // CHECK: start:
+    // CHECK-NEXT: icmp eq i32
+    // CHECK-NEXT: ret i1
+    l == r
+}
+
+// CHECK-lABEL: @non_zero_signed_eq
+#[no_mangle]
+pub fn non_zero_signed_eq(l: Option<NonZeroI64>, r: Option<NonZeroI64>) -> bool {
+    // CHECK: start:
+    // CHECK-NEXT: icmp eq i64
+    // CHECK-NEXT: ret i1
+    l == r
+}
+
+// CHECK-lABEL: @non_null_eq
+#[no_mangle]
+pub fn non_null_eq(l: Option<NonNull<u8>>, r: Option<NonNull<u8>>) -> bool {
+    // CHECK: start:
+    // CHECK-NEXT: icmp eq {{(i8\*|ptr)}}
+    // CHECK-NEXT: ret i1
+    l == r
+}