Auto merge of #115126 - Dylan-DPC:rollup-g6w3qjd, r=Dylan-DPC

Rollup of 7 pull requests

Successful merges:

 - #114930 (Automatically add OS labels to std PRs)
 - #115053 (docs: Add example, reference link for `type` keyword.)
 - #115092 (Add generics_of to smir)
 - #115096 (Add regression test for not `memcpy`ing padding bytes)
 - #115100 (Add support for `ptr::write`s for the `invalid_reference_casting` lint)
 - #115114 (Contents of reachable statics is reachable)
 - #115122 (Fix clippy lint for identical `if`/`else` contraining `?` expressions)

r? `@ghost`
`@rustbot` modify labels: rollup

Author: bors

compiler/rustc_lint/src/reference_casting.rs

@@ -56,20 +56,7 @@ impl<'tcx> LateLintPass<'tcx> for InvalidReferenceCasting {
     }
 
     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) {
-        // &mut <expr>
-        let inner = if let ExprKind::AddrOf(_, Mutability::Mut, expr) = expr.kind {
-            expr
-        // <expr> = ...
-        } else if let ExprKind::Assign(expr, _, _) = expr.kind {
-            expr
-        // <expr> += ...
-        } else if let ExprKind::AssignOp(_, expr, _) = expr.kind {
-            expr
-        } else {
-            return;
-        };
-
-        let ExprKind::Unary(UnOp::Deref, e) = &inner.kind else {
+        let Some((is_assignment, e)) = is_operation_we_care_about(cx, expr) else {
             return;
         };
 
@@ -86,15 +73,58 @@ impl<'tcx> LateLintPass<'tcx> for InvalidReferenceCasting {
         cx.emit_spanned_lint(
             INVALID_REFERENCE_CASTING,
             expr.span,
-            if matches!(expr.kind, ExprKind::AddrOf(..)) {
-                InvalidReferenceCastingDiag::BorrowAsMut { orig_cast }
-            } else {
+            if is_assignment {
                 InvalidReferenceCastingDiag::AssignToRef { orig_cast }
+            } else {
+                InvalidReferenceCastingDiag::BorrowAsMut { orig_cast }
             },
         );
     }
 }
 
+fn is_operation_we_care_about<'tcx>(
+    cx: &LateContext<'tcx>,
+    e: &'tcx Expr<'tcx>,
+) -> Option<(bool, &'tcx Expr<'tcx>)> {
+    fn deref_assign_or_addr_of<'tcx>(expr: &'tcx Expr<'tcx>) -> Option<(bool, &'tcx Expr<'tcx>)> {
+        // &mut <expr>
+        let inner = if let ExprKind::AddrOf(_, Mutability::Mut, expr) = expr.kind {
+            expr
+        // <expr> = ...
+        } else if let ExprKind::Assign(expr, _, _) = expr.kind {
+            expr
+        // <expr> += ...
+        } else if let ExprKind::AssignOp(_, expr, _) = expr.kind {
+            expr
+        } else {
+            return None;
+        };
+
+        if let ExprKind::Unary(UnOp::Deref, e) = &inner.kind {
+            Some((!matches!(expr.kind, ExprKind::AddrOf(..)), e))
+        } else {
+            None
+        }
+    }
+
+    fn ptr_write<'tcx>(
+        cx: &LateContext<'tcx>,
+        e: &'tcx Expr<'tcx>,
+    ) -> Option<(bool, &'tcx Expr<'tcx>)> {
+        if let ExprKind::Call(path, [arg_ptr, _arg_val]) = e.kind
+            && let ExprKind::Path(ref qpath) = path.kind
+            && let Some(def_id) = cx.qpath_res(qpath, path.hir_id).opt_def_id()
+            && matches!(cx.tcx.get_diagnostic_name(def_id), Some(sym::ptr_write | sym::ptr_write_volatile | sym::ptr_write_unaligned))
+        {
+            Some((true, arg_ptr))
+        } else {
+            None
+        }
+    }
+
+    deref_assign_or_addr_of(e).or_else(|| ptr_write(cx, e))
+}
+
 fn is_cast_from_const_to_mut<'tcx>(cx: &LateContext<'tcx>, e: &'tcx Expr<'tcx>) -> bool {
     let e = e.peel_blocks();
 

compiler/rustc_passes/src/reachable.rs

@@ -98,15 +98,11 @@ impl<'tcx> Visitor<'tcx> for ReachableContext<'tcx> {
                 self.worklist.push(def_id);
             } else {
                 match res {
-                    // If this path leads to a constant, then we need to
-                    // recurse into the constant to continue finding
-                    // items that are reachable.
-                    Res::Def(DefKind::Const | DefKind::AssocConst, _) => {
+                    // Reachable constants and reachable statics can have their contents inlined
+                    // into other crates. Mark them as reachable and recurse into their body.
+                    Res::Def(DefKind::Const | DefKind::AssocConst | DefKind::Static(_), _) => {
                         self.worklist.push(def_id);
                     }
-
-                    // If this wasn't a static, then the destination is
-                    // surely reachable.
                     _ => {
                         self.reachable_symbols.insert(def_id);
                     }

compiler/rustc_smir/src/rustc_internal/mod.rs

@@ -80,6 +80,10 @@ impl<'tcx> Tables<'tcx> {
         self.def_ids[impl_def.0]
     }
 
+    pub fn generic_def_id(&self, generic_def: &stable_mir::ty::GenericDef) -> DefId {
+        self.def_ids[generic_def.0]
+    }
+
     pub fn crate_item(&mut self, did: DefId) -> stable_mir::CrateItem {
         stable_mir::CrateItem(self.create_def_id(did))
     }
@@ -120,6 +124,10 @@ impl<'tcx> Tables<'tcx> {
         stable_mir::ty::TraitDef(self.create_def_id(did))
     }
 
+    pub fn generic_def(&mut self, did: DefId) -> stable_mir::ty::GenericDef {
+        stable_mir::ty::GenericDef(self.create_def_id(did))
+    }
+
     pub fn const_def(&mut self, did: DefId) -> stable_mir::ty::ConstDef {
         stable_mir::ty::ConstDef(self.create_def_id(did))
     }

compiler/rustc_smir/src/rustc_smir/mod.rs

@@ -10,7 +10,8 @@
 use crate::rustc_internal::{self, opaque};
 use crate::stable_mir::mir::{CopyNonOverlapping, UserTypeProjection, VariantIdx};
 use crate::stable_mir::ty::{
-    allocation_filter, new_allocation, Const, FloatTy, IntTy, Movability, RigidTy, TyKind, UintTy,
+    allocation_filter, new_allocation, Const, FloatTy, GenericDef, GenericParamDef, IntTy,
+    Movability, RigidTy, TyKind, UintTy,
 };
 use crate::stable_mir::{self, Context};
 use rustc_hir as hir;
@@ -101,6 +102,12 @@ impl<'tcx> Context for Tables<'tcx> {
         let ty = self.types[ty.0];
         ty.stable(self)
     }
+
+    fn generics_of(&mut self, generic_def: &GenericDef) -> stable_mir::ty::Generics {
+        let def_id = self.generic_def_id(generic_def);
+        let generic_def = self.tcx.generics_of(def_id);
+        generic_def.stable(self)
+    }
 }
 
 pub struct Tables<'tcx> {
@@ -1205,3 +1212,67 @@ impl<'tcx> Stable<'tcx> for ty::TraitRef<'tcx> {
         TraitRef { def_id: rustc_internal::trait_def(self.def_id), args: self.args.stable(tables) }
     }
 }
+
+impl<'tcx> Stable<'tcx> for ty::Generics {
+    type T = stable_mir::ty::Generics;
+
+    fn stable(&self, tables: &mut Tables<'tcx>) -> Self::T {
+        use stable_mir::ty::Generics;
+
+        let params: Vec<_> = self.params.iter().map(|param| param.stable(tables)).collect();
+        let param_def_id_to_index =
+            params.iter().map(|param| (param.def_id, param.index)).collect();
+
+        Generics {
+            parent: self.parent.map(|did| tables.generic_def(did)),
+            parent_count: self.parent_count,
+            params,
+            param_def_id_to_index,
+            has_self: self.has_self,
+            has_late_bound_regions: self
+                .has_late_bound_regions
+                .as_ref()
+                .map(|late_bound_regions| late_bound_regions.stable(tables)),
+            host_effect_index: self.host_effect_index,
+        }
+    }
+}
+
+impl<'tcx> Stable<'tcx> for rustc_span::Span {
+    type T = stable_mir::ty::Span;
+
+    fn stable(&self, _: &mut Tables<'tcx>) -> Self::T {
+        opaque(self)
+    }
+}
+
+impl<'tcx> Stable<'tcx> for rustc_middle::ty::GenericParamDefKind {
+    type T = stable_mir::ty::GenericParamDefKind;
+
+    fn stable(&self, _: &mut Tables<'tcx>) -> Self::T {
+        use stable_mir::ty::GenericParamDefKind;
+        match self {
+            ty::GenericParamDefKind::Lifetime => GenericParamDefKind::Lifetime,
+            ty::GenericParamDefKind::Type { has_default, synthetic } => {
+                GenericParamDefKind::Type { has_default: *has_default, synthetic: *synthetic }
+            }
+            ty::GenericParamDefKind::Const { has_default } => {
+                GenericParamDefKind::Const { has_default: *has_default }
+            }
+        }
+    }
+}
+
+impl<'tcx> Stable<'tcx> for rustc_middle::ty::GenericParamDef {
+    type T = stable_mir::ty::GenericParamDef;
+
+    fn stable(&self, tables: &mut Tables<'tcx>) -> Self::T {
+        GenericParamDef {
+            name: self.name.to_string(),
+            def_id: tables.generic_def(self.def_id),
+            index: self.index,
+            pure_wrt_drop: self.pure_wrt_drop,
+            kind: self.kind.stable(tables),
+        }
+    }
+}

compiler/rustc_smir/src/stable_mir/mod.rs

@@ -15,7 +15,7 @@ use std::cell::Cell;
 
 use crate::rustc_smir::Tables;
 
-use self::ty::{ImplDef, ImplTrait, TraitDecl, TraitDef, Ty, TyKind};
+use self::ty::{GenericDef, Generics, ImplDef, ImplTrait, TraitDecl, TraitDef, Ty, TyKind};
 
 pub mod mir;
 pub mod ty;
@@ -110,6 +110,7 @@ pub trait Context {
     fn trait_decl(&mut self, trait_def: &TraitDef) -> TraitDecl;
     fn all_trait_impls(&mut self) -> ImplTraitDecls;
     fn trait_impl(&mut self, trait_impl: &ImplDef) -> ImplTrait;
+    fn generics_of(&mut self, generic_def: &GenericDef) -> Generics;
     /// Get information about the local crate.
     fn local_crate(&self) -> Crate;
     /// Retrieve a list of all external crates.

compiler/rustc_smir/src/stable_mir/ty.rs

@@ -22,7 +22,7 @@ pub struct Const {
 
 type Ident = Opaque;
 pub(crate) type Region = Opaque;
-type Span = Opaque;
+pub type Span = Opaque;
 
 #[derive(Clone, Debug)]
 pub enum TyKind {
@@ -87,34 +87,37 @@ pub enum Movability {
     Movable,
 }
 
-#[derive(Clone, PartialEq, Eq, Debug)]
+#[derive(Clone, Copy, PartialEq, Eq, Debug)]
 pub struct ForeignDef(pub(crate) DefId);
 
-#[derive(Clone, PartialEq, Eq, Debug)]
+#[derive(Clone, Copy, PartialEq, Eq, Debug)]
 pub struct FnDef(pub(crate) DefId);
 
-#[derive(Clone, PartialEq, Eq, Debug)]
+#[derive(Clone, Copy, PartialEq, Eq, Debug)]
 pub struct ClosureDef(pub(crate) DefId);
 
-#[derive(Clone, PartialEq, Eq, Debug)]
+#[derive(Clone, Copy, PartialEq, Eq, Debug)]
 pub struct GeneratorDef(pub(crate) DefId);
 
-#[derive(Clone, PartialEq, Eq, Debug)]
+#[derive(Clone, Copy, PartialEq, Eq, Debug)]
 pub struct ParamDef(pub(crate) DefId);
 
-#[derive(Clone, PartialEq, Eq, Debug)]
+#[derive(Clone, Copy, PartialEq, Eq, Debug)]
 pub struct BrNamedDef(pub(crate) DefId);
 
-#[derive(Clone, PartialEq, Eq, Debug)]
+#[derive(Clone, Copy, PartialEq, Eq, Debug)]
 pub struct AdtDef(pub(crate) DefId);
 
-#[derive(Clone, PartialEq, Eq, Debug)]
+#[derive(Clone, Copy, PartialEq, Eq, Debug)]
 pub struct AliasDef(pub(crate) DefId);
 
-#[derive(Clone, PartialEq, Eq, Debug)]
+#[derive(Clone, Copy, PartialEq, Eq, Debug)]
 pub struct TraitDef(pub(crate) DefId);
 
-#[derive(Clone, PartialEq, Eq, Debug)]
+#[derive(Clone, Copy, PartialEq, Eq, Debug)]
+pub struct GenericDef(pub(crate) DefId);
+
+#[derive(Clone, Copy, PartialEq, Eq, Debug)]
 pub struct ConstDef(pub(crate) DefId);
 
 impl TraitDef {
@@ -132,6 +135,12 @@ impl ImplDef {
     }
 }
 
+impl GenericDef {
+    pub fn generics_of(&self) -> Generics {
+        with(|tcx| tcx.generics_of(self))
+    }
+}
+
 #[derive(Clone, Debug)]
 pub struct GenericArgs(pub Vec<GenericArgKind>);
 
@@ -461,3 +470,30 @@ pub struct TraitRef {
     pub def_id: TraitDef,
     pub args: GenericArgs,
 }
+
+#[derive(Clone, Debug)]
+pub struct Generics {
+    pub parent: Option<GenericDef>,
+    pub parent_count: usize,
+    pub params: Vec<GenericParamDef>,
+    pub param_def_id_to_index: Vec<(GenericDef, u32)>,
+    pub has_self: bool,
+    pub has_late_bound_regions: Option<Span>,
+    pub host_effect_index: Option<usize>,
+}
+
+#[derive(Clone, Debug)]
+pub enum GenericParamDefKind {
+    Lifetime,
+    Type { has_default: bool, synthetic: bool },
+    Const { has_default: bool },
+}
+
+#[derive(Clone, Debug)]
+pub struct GenericParamDef {
+    pub name: super::Symbol,
+    pub def_id: GenericDef,
+    pub index: u32,
+    pub pure_wrt_drop: bool,
+    pub kind: GenericParamDefKind,
+}

compiler/rustc_span/src/symbol.rs

@@ -1179,6 +1179,9 @@ symbols! {
         ptr_offset_from,
         ptr_offset_from_unsigned,
         ptr_unique,
+        ptr_write,
+        ptr_write_unaligned,
+        ptr_write_volatile,
         pub_macro_rules,
         pub_restricted,
         public,

library/core/src/ptr/mod.rs

@@ -1357,6 +1357,7 @@ pub const unsafe fn read_unaligned<T>(src: *const T) -> T {
 #[inline]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_const_unstable(feature = "const_ptr_write", issue = "86302")]
+#[rustc_diagnostic_item = "ptr_write"]
 #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
 pub const unsafe fn write<T>(dst: *mut T, src: T) {
     // Semantically, it would be fine for this to be implemented as a
@@ -1459,6 +1460,7 @@ pub const unsafe fn write<T>(dst: *mut T, src: T) {
 #[inline]
 #[stable(feature = "ptr_unaligned", since = "1.17.0")]
 #[rustc_const_unstable(feature = "const_ptr_write", issue = "86302")]
+#[rustc_diagnostic_item = "ptr_write_unaligned"]
 #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
 pub const unsafe fn write_unaligned<T>(dst: *mut T, src: T) {
     // SAFETY: the caller must guarantee that `dst` is valid for writes.
@@ -1607,6 +1609,7 @@ pub unsafe fn read_volatile<T>(src: *const T) -> T {
 /// ```
 #[inline]
 #[stable(feature = "volatile", since = "1.9.0")]
+#[rustc_diagnostic_item = "ptr_write_volatile"]
 #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
 pub unsafe fn write_volatile<T>(dst: *mut T, src: T) {
     // SAFETY: the caller must uphold the safety contract for `volatile_store`.

library/std/src/keyword_docs.rs

@@ -1820,7 +1820,7 @@ mod true_keyword {}
 
 #[doc(keyword = "type")]
 //
-/// Define an alias for an existing type.
+/// Define an [alias] for an existing type.
 ///
 /// The syntax is `type Name = ExistingType;`.
 ///
@@ -1838,6 +1838,13 @@ mod true_keyword {}
 /// assert_eq!(m, k);
 /// ```
 ///
+/// A type can be generic:
+///
+/// ```rust
+/// # use std::sync::{Arc, Mutex};
+/// type ArcMutex<T> = Arc<Mutex<T>>;
+/// ```
+///
 /// In traits, `type` is used to declare an [associated type]:
 ///
 /// ```rust
@@ -1860,6 +1867,7 @@ mod true_keyword {}
 ///
 /// [`trait`]: keyword.trait.html
 /// [associated type]: ../reference/items/associated-items.html#associated-types
+/// [alias]: ../reference/items/type-aliases.html
 mod type_keyword {}
 
 #[doc(keyword = "unsafe")]