Auto merge of rust-lang#120165 - reitermarkus:nonzero-switch-alias-direction, r=dtolnay

Switch `NonZero` alias direction.

Step 4 mentioned in rust-lang#100428 (review).

Depends on rust-lang#120160.

r? `@dtolnay`

Author: bors

compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs

@@ -2140,46 +2140,50 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         expr_ty: Ty<'tcx>,
     ) -> bool {
         let tcx = self.tcx;
-        let (adt, unwrap) = match expected.kind() {
+        let (adt, substs, unwrap) = match expected.kind() {
             // In case Option<NonZero*> is wanted, but * is provided, suggest calling new
-            ty::Adt(adt, args) if tcx.is_diagnostic_item(sym::Option, adt.did()) => {
-                // Unwrap option
-                let ty::Adt(adt, _) = args.type_at(0).kind() else {
+            ty::Adt(adt, substs) if tcx.is_diagnostic_item(sym::Option, adt.did()) => {
+                let nonzero_type = substs.type_at(0); // Unwrap option type.
+                let ty::Adt(adt, substs) = nonzero_type.kind() else {
                     return false;
                 };
-
-                (adt, "")
+                (adt, substs, "")
             }
-            // In case NonZero* is wanted, but * is provided also add `.unwrap()` to satisfy types
-            ty::Adt(adt, _) => (adt, ".unwrap()"),
+            // In case `NonZero<*>` is wanted but `*` is provided, also add `.unwrap()` to satisfy types.
+            ty::Adt(adt, substs) => (adt, substs, ".unwrap()"),
             _ => return false,
         };
 
-        let map = [
-            (sym::NonZeroU8, tcx.types.u8),
-            (sym::NonZeroU16, tcx.types.u16),
-            (sym::NonZeroU32, tcx.types.u32),
-            (sym::NonZeroU64, tcx.types.u64),
-            (sym::NonZeroU128, tcx.types.u128),
-            (sym::NonZeroI8, tcx.types.i8),
-            (sym::NonZeroI16, tcx.types.i16),
-            (sym::NonZeroI32, tcx.types.i32),
-            (sym::NonZeroI64, tcx.types.i64),
-            (sym::NonZeroI128, tcx.types.i128),
+        if !self.tcx.is_diagnostic_item(sym::NonZero, adt.did()) {
+            return false;
+        }
+
+        // FIXME: This can be simplified once `NonZero<T>` is stable.
+        let coercable_types = [
+            ("NonZeroU8", tcx.types.u8),
+            ("NonZeroU16", tcx.types.u16),
+            ("NonZeroU32", tcx.types.u32),
+            ("NonZeroU64", tcx.types.u64),
+            ("NonZeroU128", tcx.types.u128),
+            ("NonZeroI8", tcx.types.i8),
+            ("NonZeroI16", tcx.types.i16),
+            ("NonZeroI32", tcx.types.i32),
+            ("NonZeroI64", tcx.types.i64),
+            ("NonZeroI128", tcx.types.i128),
         ];
 
-        let Some((s, _)) = map.iter().find(|&&(s, t)| {
-            self.tcx.is_diagnostic_item(s, adt.did()) && self.can_coerce(expr_ty, t)
+        let int_type = substs.type_at(0);
+
+        let Some(nonzero_alias) = coercable_types.iter().find_map(|(nonzero_alias, t)| {
+            if *t == int_type && self.can_coerce(expr_ty, *t) { Some(nonzero_alias) } else { None }
         }) else {
             return false;
         };
 
-        let path = self.tcx.def_path_str(adt.non_enum_variant().def_id);
-
         err.multipart_suggestion(
-            format!("consider calling `{s}::new`"),
+            format!("consider calling `{nonzero_alias}::new`"),
             vec![
-                (expr.span.shrink_to_lo(), format!("{path}::new(")),
+                (expr.span.shrink_to_lo(), format!("{nonzero_alias}::new(")),
                 (expr.span.shrink_to_hi(), format!("){unwrap}")),
             ],
             Applicability::MaybeIncorrect,

compiler/rustc_span/src/symbol.rs

@@ -246,17 +246,7 @@ symbols! {
         MutexGuard,
         N,
         NonNull,
-        NonZeroI128,
-        NonZeroI16,
-        NonZeroI32,
-        NonZeroI64,
-        NonZeroI8,
-        NonZeroU128,
-        NonZeroU16,
-        NonZeroU32,
-        NonZeroU64,
-        NonZeroU8,
-        NonZeroUsize,
+        NonZero,
         None,
         Normal,
         Ok,

library/core/src/num/mod.rs

@@ -61,7 +61,15 @@ pub use dec2flt::ParseFloatError;
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use error::ParseIntError;
 
-pub(crate) use nonzero::NonZero;
+#[unstable(
+    feature = "nonzero_internals",
+    reason = "implementation detail which may disappear or be replaced at any time",
+    issue = "none"
+)]
+pub use nonzero::ZeroablePrimitive;
+
+#[unstable(feature = "generic_nonzero", issue = "120257")]
+pub use nonzero::NonZero;
 
 #[stable(feature = "nonzero", since = "1.28.0")]
 pub use nonzero::{NonZeroU128, NonZeroU16, NonZeroU32, NonZeroU64, NonZeroU8, NonZeroUsize};

library/core/src/num/nonzero.rs

@@ -3,6 +3,8 @@
 use crate::cmp::Ordering;
 use crate::fmt;
 use crate::hash::{Hash, Hasher};
+#[cfg(bootstrap)]
+use crate::marker::StructuralEq;
 use crate::marker::StructuralPartialEq;
 use crate::ops::{BitOr, BitOrAssign, Div, Neg, Rem};
 use crate::str::FromStr;
@@ -30,9 +32,7 @@ mod private {
     issue = "none"
 )]
 #[const_trait]
-pub trait ZeroablePrimitive: Sized + Copy + private::Sealed {
-    type NonZero;
-}
+pub trait ZeroablePrimitive: Sized + Copy + private::Sealed {}
 
 macro_rules! impl_zeroable_primitive {
     ($NonZero:ident ( $primitive:ty )) => {
@@ -48,9 +48,7 @@ macro_rules! impl_zeroable_primitive {
             reason = "implementation detail which may disappear or be replaced at any time",
             issue = "none"
         )]
-        impl const ZeroablePrimitive for $primitive {
-            type NonZero = $NonZero;
-        }
+        impl const ZeroablePrimitive for $primitive {}
     };
 }
 
@@ -67,12 +65,23 @@ impl_zeroable_primitive!(NonZeroI64(i64));
 impl_zeroable_primitive!(NonZeroI128(i128));
 impl_zeroable_primitive!(NonZeroIsize(isize));
 
-#[unstable(
-    feature = "nonzero_internals",
-    reason = "implementation detail which may disappear or be replaced at any time",
-    issue = "none"
-)]
-pub(crate) type NonZero<T> = <T as ZeroablePrimitive>::NonZero;
+/// A value that is known not to equal zero.
+///
+/// This enables some memory layout optimization.
+/// For example, `Option<NonZero<u32>>` is the same size as `u32`:
+///
+/// ```
+/// #![feature(generic_nonzero)]
+/// use core::mem::size_of;
+///
+/// assert_eq!(size_of::<Option<core::num::NonZero<u32>>>(), size_of::<u32>());
+/// ```
+#[unstable(feature = "generic_nonzero", issue = "120257")]
+#[repr(transparent)]
+#[rustc_layout_scalar_valid_range_start(1)]
+#[rustc_nonnull_optimization_guaranteed]
+#[rustc_diagnostic_item = "NonZero"]
+pub struct NonZero<T: ZeroablePrimitive>(T);
 
 macro_rules! impl_nonzero_fmt {
     ( #[$stability: meta] ( $( $Trait: ident ),+ ) for $Ty: ident ) => {
@@ -131,12 +140,7 @@ macro_rules! nonzero_integer {
         ///
         /// [null pointer optimization]: crate::option#representation
         #[$stability]
-        #[derive(Copy, Eq)]
-        #[repr(transparent)]
-        #[rustc_layout_scalar_valid_range_start(1)]
-        #[rustc_nonnull_optimization_guaranteed]
-        #[rustc_diagnostic_item = stringify!($Ty)]
-        pub struct $Ty($Int);
+        pub type $Ty = NonZero<$Int>;
 
         impl $Ty {
             /// Creates a non-zero without checking whether the value is non-zero.
@@ -543,6 +547,9 @@ macro_rules! nonzero_integer {
             }
         }
 
+        #[$stability]
+        impl Copy for $Ty {}
+
         #[$stability]
         impl PartialEq for $Ty {
             #[inline]
@@ -559,6 +566,13 @@ macro_rules! nonzero_integer {
         #[unstable(feature = "structural_match", issue = "31434")]
         impl StructuralPartialEq for $Ty {}
 
+        #[$stability]
+        impl Eq for $Ty {}
+
+        #[unstable(feature = "structural_match", issue = "31434")]
+        #[cfg(bootstrap)]
+        impl StructuralEq for $Ty {}
+
         #[$stability]
         impl PartialOrd for $Ty {
             #[inline]

library/std/src/lib.rs

@@ -323,6 +323,7 @@
 #![feature(float_gamma)]
 #![feature(float_minimum_maximum)]
 #![feature(float_next_up_down)]
+#![feature(generic_nonzero)]
 #![feature(hasher_prefixfree_extras)]
 #![feature(hashmap_internals)]
 #![feature(hint_assert_unchecked)]

library/std/src/num.rs

@@ -16,6 +16,16 @@ pub use core::num::Wrapping;
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use core::num::{FpCategory, ParseFloatError, ParseIntError, TryFromIntError};
 
+#[unstable(
+    feature = "nonzero_internals",
+    reason = "implementation detail which may disappear or be replaced at any time",
+    issue = "none"
+)]
+pub use core::num::ZeroablePrimitive;
+
+#[unstable(feature = "generic_nonzero", issue = "120257")]
+pub use core::num::NonZero;
+
 #[stable(feature = "signed_nonzero", since = "1.34.0")]
 pub use core::num::{NonZeroI128, NonZeroI16, NonZeroI32, NonZeroI64, NonZeroI8, NonZeroIsize};
 #[stable(feature = "nonzero", since = "1.28.0")]

src/etc/natvis/libcore.natvis

@@ -41,40 +41,7 @@
     </Expand>
   </Type>
 
-  <Type Name="core::num::nonzero::NonZeroI8">
-    <DisplayString>{__0}</DisplayString>
-  </Type>
-  <Type Name="core::num::nonzero::NonZeroI16">
-    <DisplayString>{__0}</DisplayString>
-  </Type>
-  <Type Name="core::num::nonzero::NonZeroI32">
-    <DisplayString>{__0}</DisplayString>
-  </Type>
-  <Type Name="core::num::nonzero::NonZeroI64">
-    <DisplayString>{__0}</DisplayString>
-  </Type>
-  <Type Name="core::num::nonzero::NonZeroI128">
-    <DisplayString>{__0}</DisplayString>
-  </Type>
-  <Type Name="core::num::nonzero::NonZeroIsize">
-    <DisplayString>{__0}</DisplayString>
-  </Type>
-  <Type Name="core::num::nonzero::NonZeroU8">
-    <DisplayString>{__0}</DisplayString>
-  </Type>
-  <Type Name="core::num::nonzero::NonZeroU16">
-    <DisplayString>{__0}</DisplayString>
-  </Type>
-  <Type Name="core::num::nonzero::NonZeroU32">
-    <DisplayString>{__0}</DisplayString>
-  </Type>
-  <Type Name="core::num::nonzero::NonZeroU64">
-    <DisplayString>{__0}</DisplayString>
-  </Type>
-  <Type Name="core::num::nonzero::NonZeroU128">
-    <DisplayString>{__0}</DisplayString>
-  </Type>
-  <Type Name="core::num::nonzero::NonZeroUsize">
+  <Type Name="core::num::nonzero::NonZero&lt;*&gt;">
     <DisplayString>{__0}</DisplayString>
   </Type>
 

src/tools/clippy/clippy_lints/src/operators/arithmetic_side_effects.rs

@@ -1,11 +1,11 @@
 use super::ARITHMETIC_SIDE_EFFECTS;
 use clippy_utils::consts::{constant, constant_simple, Constant};
 use clippy_utils::diagnostics::span_lint;
-use clippy_utils::ty::type_diagnostic_name;
+use clippy_utils::ty::is_type_diagnostic_item;
 use clippy_utils::{expr_or_init, is_from_proc_macro, is_lint_allowed, peel_hir_expr_refs, peel_hir_expr_unary};
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_lint::{LateContext, LateLintPass};
-use rustc_middle::ty::Ty;
+use rustc_middle::ty::{self, Ty};
 use rustc_session::impl_lint_pass;
 use rustc_span::source_map::Spanned;
 use rustc_span::symbol::sym;
@@ -88,37 +88,44 @@ impl ArithmeticSideEffects {
     }
 
     /// Verifies built-in types that have specific allowed operations
-    fn has_specific_allowed_type_and_operation(
-        cx: &LateContext<'_>,
-        lhs_ty: Ty<'_>,
+    fn has_specific_allowed_type_and_operation<'tcx>(
+        cx: &LateContext<'tcx>,
+        lhs_ty: Ty<'tcx>,
         op: &Spanned<hir::BinOpKind>,
-        rhs_ty: Ty<'_>,
+        rhs_ty: Ty<'tcx>,
     ) -> bool {
         let is_div_or_rem = matches!(op.node, hir::BinOpKind::Div | hir::BinOpKind::Rem);
-        let is_non_zero_u = |symbol: Option<Symbol>| {
-            matches!(
-                symbol,
-                Some(
-                    sym::NonZeroU128
-                        | sym::NonZeroU16
-                        | sym::NonZeroU32
-                        | sym::NonZeroU64
-                        | sym::NonZeroU8
-                        | sym::NonZeroUsize
-                )
-            )
+        let is_non_zero_u = |cx: &LateContext<'tcx>, ty: Ty<'tcx>| {
+            let tcx = cx.tcx;
+
+            let ty::Adt(adt, substs) = ty.kind() else { return false };
+
+            if !tcx.is_diagnostic_item(sym::NonZero, adt.did()) {
+                return false;
+            };
+
+            let int_type = substs.type_at(0);
+            let unsigned_int_types = [
+                tcx.types.u8,
+                tcx.types.u16,
+                tcx.types.u32,
+                tcx.types.u64,
+                tcx.types.u128,
+                tcx.types.usize,
+            ];
+
+            unsigned_int_types.contains(&int_type)
         };
         let is_sat_or_wrap = |ty: Ty<'_>| {
-            let is_sat = type_diagnostic_name(cx, ty) == Some(sym::Saturating);
-            let is_wrap = type_diagnostic_name(cx, ty) == Some(sym::Wrapping);
-            is_sat || is_wrap
+            is_type_diagnostic_item(cx, ty, sym::Saturating) || is_type_diagnostic_item(cx, ty, sym::Wrapping)
         };
 
-        // If the RHS is NonZeroU*, then division or module by zero will never occur
-        if is_non_zero_u(type_diagnostic_name(cx, rhs_ty)) && is_div_or_rem {
+        // If the RHS is `NonZero<u*>`, then division or module by zero will never occur.
+        if is_non_zero_u(cx, rhs_ty) && is_div_or_rem {
             return true;
         }
-        // `Saturation` and `Wrapping` can overflow if the RHS is zero in a division or module
+
+        // `Saturation` and `Wrapping` can overflow if the RHS is zero in a division or module.
         if is_sat_or_wrap(lhs_ty) {
             return !is_div_or_rem;
         }