Rollup of 8 pull requests

src/libcore/cell.rs

@@ -1245,6 +1245,38 @@ impl<'b, T: ?Sized> Ref<'b, T> {
         let borrow = orig.borrow.clone();
         (Ref { value: a, borrow }, Ref { value: b, borrow: orig.borrow })
     }
+
+    /// Convert into a reference to the underlying data.
+    ///
+    /// The underlying `RefCell` can never be mutably borrowed from again and will always appear
+    /// already immutably borrowed. It is not a good idea to leak more than a constant number of
+    /// references. The `RefCell` can be immutably borrowed again if only a smaller number of leaks
+    /// have occurred in total.
+    ///
+    /// This is an associated function that needs to be used as
+    /// `Ref::leak(...)`. A method would interfere with methods of the
+    /// same name on the contents of a `RefCell` used through `Deref`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(cell_leak)]
+    /// use std::cell::{RefCell, Ref};
+    /// let cell = RefCell::new(0);
+    ///
+    /// let value = Ref::leak(cell.borrow());
+    /// assert_eq!(*value, 0);
+    ///
+    /// assert!(cell.try_borrow().is_ok());
+    /// assert!(cell.try_borrow_mut().is_err());
+    /// ```
+    #[unstable(feature = "cell_leak", issue = "69099")]
+    pub fn leak(orig: Ref<'b, T>) -> &'b T {
+        // By forgetting this Ref we ensure that the borrow counter in the RefCell never goes back
+        // to UNUSED again. No further mutable references can be created from the original cell.
+        mem::forget(orig.borrow);
+        orig.value
+    }
 }
 
 #[unstable(feature = "coerce_unsized", issue = "27732")]
@@ -1330,6 +1362,37 @@ impl<'b, T: ?Sized> RefMut<'b, T> {
         let borrow = orig.borrow.clone();
         (RefMut { value: a, borrow }, RefMut { value: b, borrow: orig.borrow })
     }
+
+    /// Convert into a mutable reference to the underlying data.
+    ///
+    /// The underlying `RefCell` can not be borrowed from again and will always appear already
+    /// mutably borrowed, making the returned reference the only to the interior.
+    ///
+    /// This is an associated function that needs to be used as
+    /// `RefMut::leak(...)`. A method would interfere with methods of the
+    /// same name on the contents of a `RefCell` used through `Deref`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(cell_leak)]
+    /// use std::cell::{RefCell, RefMut};
+    /// let cell = RefCell::new(0);
+    ///
+    /// let value = RefMut::leak(cell.borrow_mut());
+    /// assert_eq!(*value, 0);
+    /// *value = 1;
+    ///
+    /// assert!(cell.try_borrow_mut().is_err());
+    /// ```
+    #[unstable(feature = "cell_leak", issue = "69099")]
+    pub fn leak(orig: RefMut<'b, T>) -> &'b mut T {
+        // By forgetting this BorrowRefMut we ensure that the borrow counter in the RefCell never
+        // goes back to UNUSED again. No further references can be created from the original cell,
+        // making the current borrow the only reference for the remaining lifetime.
+        mem::forget(orig.borrow);
+        orig.value
+    }
 }
 
 struct BorrowRefMut<'b> {

src/libcore/intrinsics.rs

@@ -1423,13 +1423,14 @@ pub(crate) fn is_aligned_and_not_null<T>(ptr: *const T) -> bool {
 }
 
 /// Checks whether the regions of memory starting at `src` and `dst` of size
-/// `count * size_of::<T>()` overlap.
-fn overlaps<T>(src: *const T, dst: *const T, count: usize) -> bool {
+/// `count * size_of::<T>()` do *not* overlap.
+pub(crate) fn is_nonoverlapping<T>(src: *const T, dst: *const T, count: usize) -> bool {
     let src_usize = src as usize;
     let dst_usize = dst as usize;
     let size = mem::size_of::<T>().checked_mul(count).unwrap();
     let diff = if src_usize > dst_usize { src_usize - dst_usize } else { dst_usize - src_usize };
-    size > diff
+    let overlaps = size > diff;
+    !overlaps
 }
 
 /// Copies `count * size_of::<T>()` bytes from `src` to `dst`. The source
@@ -1525,7 +1526,7 @@ pub unsafe fn copy_nonoverlapping<T>(src: *const T, dst: *mut T, count: usize) {
 
     debug_assert!(is_aligned_and_not_null(src), "attempt to copy from unaligned or null pointer");
     debug_assert!(is_aligned_and_not_null(dst), "attempt to copy to unaligned or null pointer");
-    debug_assert!(!overlaps(src, dst, count), "attempt to copy to overlapping memory");
+    debug_assert!(is_nonoverlapping(src, dst, count), "attempt to copy to overlapping memory");
     copy_nonoverlapping(src, dst, count)
 }
 

src/libcore/lib.rs

@@ -267,6 +267,9 @@ mod bool;
 mod tuple;
 mod unit;
 
+#[stable(feature = "core_primitive", since = "1.43.0")]
+pub mod primitive;
+
 // Pull in the `core_arch` crate directly into libcore. The contents of
 // `core_arch` are in a different repository: rust-lang/stdarch.
 //

src/libcore/primitive.rs

@@ -0,0 +1,67 @@
+//! This module reexports the primitive types to allow usage that is not
+//! possibly shadowed by other declared types.
+//!
+//! This is normally only useful in macro generated code.
+//!
+//! An example of this is when generating a new struct and an impl for it:
+//!
+//! ```rust,compile_fail
+//! pub struct bool;
+//!
+//! impl QueryId for bool {
+//!     const SOME_PROPERTY: bool = true;
+//! }
+//!
+//! # trait QueryId { const SOME_PROPERTY: core::primitive::bool; }
+//! ```
+//!
+//! Note that the `SOME_PROPERTY` associated constant would not compile, as its
+//! type `bool` refers to the struct, rather than to the primitive bool type.
+//!
+//! A correct implementation could look like:
+//!
+//! ```rust
+//! # #[allow(non_camel_case_types)]
+//! pub struct bool;
+//!
+//! impl QueryId for bool {
+//!     const SOME_PROPERTY: core::primitive::bool = true;
+//! }
+//!
+//! # trait QueryId { const SOME_PROPERTY: core::primitive::bool; }
+//! ```
+
+#[stable(feature = "core_primitive", since = "1.43.0")]
+pub use bool;
+#[stable(feature = "core_primitive", since = "1.43.0")]
+pub use char;
+#[stable(feature = "core_primitive", since = "1.43.0")]
+pub use f32;
+#[stable(feature = "core_primitive", since = "1.43.0")]
+pub use f64;
+#[stable(feature = "core_primitive", since = "1.43.0")]
+pub use i128;
+#[stable(feature = "core_primitive", since = "1.43.0")]
+pub use i16;
+#[stable(feature = "core_primitive", since = "1.43.0")]
+pub use i32;
+#[stable(feature = "core_primitive", since = "1.43.0")]
+pub use i64;
+#[stable(feature = "core_primitive", since = "1.43.0")]
+pub use i8;
+#[stable(feature = "core_primitive", since = "1.43.0")]
+pub use isize;
+#[stable(feature = "core_primitive", since = "1.43.0")]
+pub use str;
+#[stable(feature = "core_primitive", since = "1.43.0")]
+pub use u128;
+#[stable(feature = "core_primitive", since = "1.43.0")]
+pub use u16;
+#[stable(feature = "core_primitive", since = "1.43.0")]
+pub use u32;
+#[stable(feature = "core_primitive", since = "1.43.0")]
+pub use u64;
+#[stable(feature = "core_primitive", since = "1.43.0")]
+pub use u8;
+#[stable(feature = "core_primitive", since = "1.43.0")]
+pub use usize;

src/libcore/ptr/mod.rs

@@ -72,7 +72,7 @@
 use crate::cmp::Ordering;
 use crate::fmt;
 use crate::hash;
-use crate::intrinsics;
+use crate::intrinsics::{self, is_aligned_and_not_null, is_nonoverlapping};
 use crate::mem::{self, MaybeUninit};
 
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -392,6 +392,10 @@ pub unsafe fn swap<T>(x: *mut T, y: *mut T) {
 #[inline]
 #[stable(feature = "swap_nonoverlapping", since = "1.27.0")]
 pub unsafe fn swap_nonoverlapping<T>(x: *mut T, y: *mut T, count: usize) {
+    debug_assert!(is_aligned_and_not_null(x), "attempt to swap unaligned or null pointer");
+    debug_assert!(is_aligned_and_not_null(y), "attempt to swap unaligned or null pointer");
+    debug_assert!(is_nonoverlapping(x, y, count), "attempt to swap overlapping memory");
+
     let x = x as *mut u8;
     let y = y as *mut u8;
     let len = mem::size_of::<T>() * count;
@@ -619,6 +623,7 @@ pub unsafe fn replace<T>(dst: *mut T, mut src: T) -> T {
 #[inline]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub unsafe fn read<T>(src: *const T) -> T {
+    // `copy_nonoverlapping` takes care of debug_assert.
     let mut tmp = MaybeUninit::<T>::uninit();
     copy_nonoverlapping(src, tmp.as_mut_ptr(), 1);
     tmp.assume_init()
@@ -712,6 +717,7 @@ pub unsafe fn read<T>(src: *const T) -> T {
 #[inline]
 #[stable(feature = "ptr_unaligned", since = "1.17.0")]
 pub unsafe fn read_unaligned<T>(src: *const T) -> T {
+    // `copy_nonoverlapping` takes care of debug_assert.
     let mut tmp = MaybeUninit::<T>::uninit();
     copy_nonoverlapping(src as *const u8, tmp.as_mut_ptr() as *mut u8, mem::size_of::<T>());
     tmp.assume_init()
@@ -804,6 +810,7 @@ pub unsafe fn read_unaligned<T>(src: *const T) -> T {
 #[inline]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub unsafe fn write<T>(dst: *mut T, src: T) {
+    debug_assert!(is_aligned_and_not_null(dst), "attempt to write to unaligned or null pointer");
     intrinsics::move_val_init(&mut *dst, src)
 }
 
@@ -896,6 +903,7 @@ pub unsafe fn write<T>(dst: *mut T, src: T) {
 #[inline]
 #[stable(feature = "ptr_unaligned", since = "1.17.0")]
 pub unsafe fn write_unaligned<T>(dst: *mut T, src: T) {
+    // `copy_nonoverlapping` takes care of debug_assert.
     copy_nonoverlapping(&src as *const T as *const u8, dst as *mut u8, mem::size_of::<T>());
     mem::forget(src);
 }
@@ -967,6 +975,7 @@ pub unsafe fn write_unaligned<T>(dst: *mut T, src: T) {
 #[inline]
 #[stable(feature = "volatile", since = "1.9.0")]
 pub unsafe fn read_volatile<T>(src: *const T) -> T {
+    debug_assert!(is_aligned_and_not_null(src), "attempt to read from unaligned or null pointer");
     intrinsics::volatile_load(src)
 }
 
@@ -1035,6 +1044,7 @@ pub unsafe fn read_volatile<T>(src: *const T) -> T {
 #[inline]
 #[stable(feature = "volatile", since = "1.9.0")]
 pub unsafe fn write_volatile<T>(dst: *mut T, src: T) {
+    debug_assert!(is_aligned_and_not_null(dst), "attempt to write to unaligned or null pointer");
     intrinsics::volatile_store(dst, src);
 }
 

src/librustc/ty/context.rs

@@ -1526,7 +1526,7 @@ impl<'tcx> GlobalCtxt<'tcx> {
         ty::tls::with_related_context(tcx, |icx| {
             let new_icx = ty::tls::ImplicitCtxt {
                 tcx,
-                query: icx.query.clone(),
+                query: icx.query,
                 diagnostics: icx.diagnostics,
                 layout_depth: icx.layout_depth,
                 task_deps: icx.task_deps,

src/librustc/ty/mod.rs

@@ -1447,7 +1447,7 @@ impl<'tcx> ToPredicate<'tcx> for ConstnessAnd<TraitRef<'tcx>> {
 impl<'tcx> ToPredicate<'tcx> for ConstnessAnd<&TraitRef<'tcx>> {
     fn to_predicate(&self) -> Predicate<'tcx> {
         ty::Predicate::Trait(
-            ty::Binder::dummy(ty::TraitPredicate { trait_ref: self.value.clone() }),
+            ty::Binder::dummy(ty::TraitPredicate { trait_ref: *self.value }),
             self.constness,
         )
     }

src/librustc/ty/query/job.rs

@@ -173,7 +173,7 @@ impl<'tcx> QueryLatch<'tcx> {
                 return CycleError { usage, cycle };
             }
 
-            current_job = info.job.parent.clone();
+            current_job = info.job.parent;
         }
 
         panic!("did not find a cycle")

src/librustc_ast_pretty/pprust.rs

@@ -3,7 +3,7 @@ use crate::pp::{self, Breaks};
 
 use rustc_span::edition::Edition;
 use rustc_span::source_map::{SourceMap, Spanned};
-use rustc_span::symbol::{kw, sym};
+use rustc_span::symbol::{kw, sym, IdentPrinter};
 use rustc_span::{BytePos, FileName, Span};
 use syntax::ast::{self, BlockCheckMode, PatKind, RangeEnd, RangeSyntax};
 use syntax::ast::{Attribute, GenericArg, MacArgs};
@@ -196,40 +196,6 @@ pub fn literal_to_string(lit: token::Lit) -> String {
     out
 }
 
-/// Print an ident from AST, `$crate` is converted into its respective crate name.
-pub fn ast_ident_to_string(ident: ast::Ident, is_raw: bool) -> String {
-    ident_to_string(ident.name, is_raw, Some(ident.span))
-}
-
-// AST pretty-printer is used as a fallback for turning AST structures into token streams for
-// proc macros. Additionally, proc macros may stringify their input and expect it survive the
-// stringification (especially true for proc macro derives written between Rust 1.15 and 1.30).
-// So we need to somehow pretty-print `$crate` in a way preserving at least some of its
-// hygiene data, most importantly name of the crate it refers to.
-// As a result we print `$crate` as `crate` if it refers to the local crate
-// and as `::other_crate_name` if it refers to some other crate.
-// Note, that this is only done if the ident token is printed from inside of AST pretty-pringing,
-// but not otherwise. Pretty-printing is the only way for proc macros to discover token contents,
-// so we should not perform this lossy conversion if the top level call to the pretty-printer was
-// done for a token stream or a single token.
-fn ident_to_string(name: ast::Name, is_raw: bool, convert_dollar_crate: Option<Span>) -> String {
-    if is_raw {
-        format!("r#{}", name)
-    } else {
-        if name == kw::DollarCrate {
-            if let Some(span) = convert_dollar_crate {
-                let converted = span.ctxt().dollar_crate_name();
-                return if converted.is_path_segment_keyword() {
-                    converted.to_string()
-                } else {
-                    format!("::{}", converted)
-                };
-            }
-        }
-        name.to_string()
-    }
-}
-
 /// Print the token kind precisely, without converting `$crate` into its respective crate name.
 pub fn token_kind_to_string(tok: &TokenKind) -> String {
     token_kind_to_string_ext(tok, None)
@@ -280,7 +246,7 @@ fn token_kind_to_string_ext(tok: &TokenKind, convert_dollar_crate: Option<Span>)
         token::Literal(lit) => literal_to_string(lit),
 
         /* Name components */
-        token::Ident(s, is_raw) => ident_to_string(s, is_raw, convert_dollar_crate),
+        token::Ident(s, is_raw) => IdentPrinter::new(s, is_raw, convert_dollar_crate).to_string(),
         token::Lifetime(s) => s.to_string(),
 
         /* Other */
@@ -315,14 +281,11 @@ pub fn nonterminal_to_string(nt: &Nonterminal) -> String {
         token::NtBlock(ref e) => block_to_string(e),
         token::NtStmt(ref e) => stmt_to_string(e),
         token::NtPat(ref e) => pat_to_string(e),
-        token::NtIdent(e, is_raw) => ast_ident_to_string(e, is_raw),
+        token::NtIdent(e, is_raw) => IdentPrinter::for_ast_ident(e, is_raw).to_string(),
         token::NtLifetime(e) => e.to_string(),
         token::NtLiteral(ref e) => expr_to_string(e),
         token::NtTT(ref tree) => tt_to_string(tree.clone()),
-        // FIXME(Centril): merge these variants.
-        token::NtImplItem(ref e) | token::NtTraitItem(ref e) => assoc_item_to_string(e),
         token::NtVis(ref e) => vis_to_string(e),
-        token::NtForeignItem(ref e) => foreign_item_to_string(e),
     }
 }
 
@@ -358,10 +321,6 @@ pub fn item_to_string(i: &ast::Item) -> String {
     to_string(|s| s.print_item(i))
 }
 
-fn assoc_item_to_string(i: &ast::AssocItem) -> String {
-    to_string(|s| s.print_assoc_item(i))
-}
-
 pub fn generic_params_to_string(generic_params: &[ast::GenericParam]) -> String {
     to_string(|s| s.print_generic_params(generic_params))
 }
@@ -404,10 +363,6 @@ pub fn param_to_string(arg: &ast::Param) -> String {
     to_string(|s| s.print_param(arg, false))
 }
 
-fn foreign_item_to_string(arg: &ast::ForeignItem) -> String {
-    to_string(|s| s.print_foreign_item(arg))
-}
-
 fn visibility_qualified(vis: &ast::Visibility, s: &str) -> String {
     format!("{}{}", to_string(|s| s.print_visibility(vis)), s)
 }
@@ -819,7 +774,7 @@ impl<'a> PrintState<'a> for State<'a> {
     }
 
     fn print_ident(&mut self, ident: ast::Ident) {
-        self.s.word(ast_ident_to_string(ident, ident.is_raw_guess()));
+        self.s.word(IdentPrinter::for_ast_ident(ident, ident.is_raw_guess()).to_string());
         self.ann.post(self, AnnNode::Ident(&ident))
     }
 

src/librustc_codegen_ssa/mir/constant.rs

@@ -31,7 +31,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
             _ => {
                 let val = self.eval_mir_constant(constant)?;
                 let ty = self.monomorphize(&constant.literal.ty);
-                Ok(OperandRef::from_const(bx, val.clone(), ty))
+                Ok(OperandRef::from_const(bx, val, ty))
             }
         }
     }