Add [f32]::sort_floats and [f64]::sort_floats

It's inconvenient to sort a slice or Vec of floats, compared to sorting
integers. To simplify numeric code, add a convenience method to `[f32]`
and `[f64]` to sort them using `sort_unstable_by` with `total_cmp`.

Add lang items slice_f32 and slice_f64 to handle the two new impl
blocks.

Author: joshtriplett

compiler/rustc_hir/src/lang_items.rs

@@ -169,6 +169,8 @@ language_item_table! {
     Str,                     sym::str,                 str_impl,                   Target::Impl,           GenericRequirement::None;
     Array,                   sym::array,               array_impl,                 Target::Impl,           GenericRequirement::None;
     Slice,                   sym::slice,               slice_impl,                 Target::Impl,           GenericRequirement::None;
+    SliceF32,                sym::slice_f32,           slice_f32_impl,             Target::Impl,           GenericRequirement::None;
+    SliceF64,                sym::slice_f64,           slice_f64_impl,             Target::Impl,           GenericRequirement::None;
     SliceU8,                 sym::slice_u8,            slice_u8_impl,              Target::Impl,           GenericRequirement::None;
     StrAlloc,                sym::str_alloc,           str_alloc_impl,             Target::Impl,           GenericRequirement::None;
     SliceAlloc,              sym::slice_alloc,         slice_alloc_impl,           Target::Impl,           GenericRequirement::None;

compiler/rustc_span/src/symbol.rs

@@ -1295,6 +1295,8 @@ symbols! {
         skip,
         slice,
         slice_alloc,
+        slice_f32,
+        slice_f64,
         slice_len_fn,
         slice_patterns,
         slice_u8,

compiler/rustc_typeck/src/check/method/probe.rs

@@ -668,6 +668,8 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
             ty::Slice(_) => {
                 for lang_def_id in [
                     lang_items.slice_impl(),
+                    lang_items.slice_f32_impl(),
+                    lang_items.slice_f64_impl(),
                     lang_items.slice_u8_impl(),
                     lang_items.slice_alloc_impl(),
                     lang_items.slice_u8_alloc_impl(),

compiler/rustc_typeck/src/coherence/inherent_impls.rs

@@ -114,6 +114,28 @@ impl<'tcx> ItemLikeVisitor<'_> for InherentCollect<'tcx> {
                     assoc_items,
                 );
             }
+            ty::Slice(slice_item) if slice_item == self.tcx.types.f32 => {
+                self.check_primitive_impl(
+                    item.def_id,
+                    lang_items.slice_f32_impl(),
+                    None,
+                    "slice_f32",
+                    "[f32]",
+                    item.span,
+                    assoc_items,
+                );
+            }
+            ty::Slice(slice_item) if slice_item == self.tcx.types.f64 => {
+                self.check_primitive_impl(
+                    item.def_id,
+                    lang_items.slice_f64_impl(),
+                    None,
+                    "slice_f64",
+                    "[f64]",
+                    item.span,
+                    assoc_items,
+                );
+            }
             ty::Slice(_) => {
                 self.check_primitive_impl(
                     item.def_id,

library/core/src/lib.rs

@@ -151,6 +151,8 @@
 #![feature(variant_count)]
 #![feature(const_array_from_ref)]
 #![feature(const_slice_from_ref)]
+// Library features:
+#![feature(total_cmp)]
 //
 // Language features:
 #![feature(abi_unadjusted)]

library/core/src/slice/mod.rs

@@ -3983,6 +3983,68 @@ impl<T> [T] {
     }
 }
 
+#[cfg(not(bootstrap))]
+#[cfg(not(test))]
+#[lang = "slice_f32"]
+impl [f32] {
+    /// Sorts the slice of floats.
+    ///
+    /// This sort is in-place (i.e. does not allocate), *O*(*n* \* log(*n*)) worst-case, and uses
+    /// the ordering defined by [`f32::total_cmp`].
+    ///
+    /// # Current implementation
+    ///
+    /// This uses the same sorting algorithm as [`sort_unstable_by`](slice::sort_unstable_by).
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(sort_floats)]
+    /// let mut v = [2.6, -5e-8, f32::NAN, 8.29, f32::INFINITY, -1.0, 0.0, -f32::INFINITY, -0.0];
+    ///
+    /// v.sort_floats();
+    /// let sorted = [-f32::INFINITY, -1.0, -5e-8, -0.0, 0.0, 2.6, 8.29, f32::INFINITY, f32::NAN];
+    /// assert_eq!(&v[..8], &sorted[..8]);
+    /// assert!(v[8].is_nan());
+    /// ```
+    #[unstable(feature = "sort_floats", issue = "93396")]
+    #[inline]
+    pub fn sort_floats(&mut self) {
+        self.sort_unstable_by(f32::total_cmp);
+    }
+}
+
+#[cfg(not(bootstrap))]
+#[cfg(not(test))]
+#[lang = "slice_f64"]
+impl [f64] {
+    /// Sorts the slice of floats.
+    ///
+    /// This sort is in-place (i.e. does not allocate), *O*(*n* \* log(*n*)) worst-case, and uses
+    /// the ordering defined by [`f64::total_cmp`].
+    ///
+    /// # Current implementation
+    ///
+    /// This uses the same sorting algorithm as [`sort_unstable_by`](slice::sort_unstable_by).
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(sort_floats)]
+    /// let mut v = [2.6, -5e-8, f64::NAN, 8.29, f64::INFINITY, -1.0, 0.0, -f64::INFINITY, -0.0];
+    ///
+    /// v.sort_floats();
+    /// let sorted = [-f64::INFINITY, -1.0, -5e-8, -0.0, 0.0, 2.6, 8.29, f64::INFINITY, f64::NAN];
+    /// assert_eq!(&v[..8], &sorted[..8]);
+    /// assert!(v[8].is_nan());
+    /// ```
+    #[unstable(feature = "sort_floats", issue = "93396")]
+    #[inline]
+    pub fn sort_floats(&mut self) {
+        self.sort_unstable_by(f64::total_cmp);
+    }
+}
+
 trait CloneFromSpec<T> {
     fn spec_clone_from(&mut self, src: &[T]);
 }

src/librustdoc/clean/types.rs

@@ -1648,18 +1648,18 @@ impl PrimitiveType {
         }
     }
 
-    crate fn impls(&self, tcx: TyCtxt<'_>) -> &'static ArrayVec<DefId, 4> {
+    crate fn impls(&self, tcx: TyCtxt<'_>) -> &'static ArrayVec<DefId, 6> {
         Self::all_impls(tcx).get(self).expect("missing impl for primitive type")
     }
 
-    crate fn all_impls(tcx: TyCtxt<'_>) -> &'static FxHashMap<PrimitiveType, ArrayVec<DefId, 4>> {
-        static CELL: OnceCell<FxHashMap<PrimitiveType, ArrayVec<DefId, 4>>> = OnceCell::new();
+    crate fn all_impls(tcx: TyCtxt<'_>) -> &'static FxHashMap<PrimitiveType, ArrayVec<DefId, 6>> {
+        static CELL: OnceCell<FxHashMap<PrimitiveType, ArrayVec<DefId, 6>>> = OnceCell::new();
 
         CELL.get_or_init(move || {
             use self::PrimitiveType::*;
 
             let single = |a: Option<DefId>| a.into_iter().collect();
-            let both = |a: Option<DefId>, b: Option<DefId>| -> ArrayVec<_, 4> {
+            let both = |a: Option<DefId>, b: Option<DefId>| -> ArrayVec<_, 6> {
                 a.into_iter().chain(b).collect()
             };
 
@@ -1686,6 +1686,8 @@ impl PrimitiveType {
                     lang_items
                         .slice_impl()
                         .into_iter()
+                        .chain(lang_items.slice_f32_impl())
+                        .chain(lang_items.slice_f64_impl())
                         .chain(lang_items.slice_u8_impl())
                         .chain(lang_items.slice_alloc_impl())
                         .chain(lang_items.slice_u8_alloc_impl())