Rollup of 6 pull requests

compiler/rustc_lint/src/internal.rs

@@ -10,7 +10,7 @@ use rustc_hir::{GenericArg, HirId, MutTy, Mutability, Path, PathSegment, QPath,
 use rustc_middle::ty;
 use rustc_session::{declare_lint_pass, declare_tool_lint, impl_lint_pass};
 use rustc_span::hygiene::{ExpnKind, MacroKind};
-use rustc_span::symbol::{sym, Ident, Symbol};
+use rustc_span::symbol::{kw, sym, Ident, Symbol};
 
 declare_tool_lint! {
     pub rustc::DEFAULT_HASH_TYPES,
@@ -267,3 +267,47 @@ impl EarlyLintPass for LintPassImpl {
         }
     }
 }
+
+declare_tool_lint! {
+    pub rustc::EXISTING_DOC_KEYWORD,
+    Allow,
+    "Check that documented keywords in std and core actually exist",
+    report_in_external_macro: true
+}
+
+declare_lint_pass!(ExistingDocKeyword => [EXISTING_DOC_KEYWORD]);
+
+fn is_doc_keyword(s: Symbol) -> bool {
+    s <= kw::Union
+}
+
+impl<'tcx> LateLintPass<'tcx> for ExistingDocKeyword {
+    fn check_item(&mut self, cx: &LateContext<'_>, item: &rustc_hir::Item<'_>) {
+        for attr in item.attrs {
+            if !attr.has_name(sym::doc) {
+                continue;
+            }
+            if let Some(list) = attr.meta_item_list() {
+                for nested in list {
+                    if nested.has_name(sym::keyword) {
+                        let v = nested
+                            .value_str()
+                            .expect("#[doc(keyword = \"...\")] expected a value!");
+                        if is_doc_keyword(v) {
+                            return;
+                        }
+                        cx.struct_span_lint(EXISTING_DOC_KEYWORD, attr.span, |lint| {
+                            lint.build(&format!(
+                                "Found non-existing keyword `{}` used in \
+                                     `#[doc(keyword = \"...\")]`",
+                                v,
+                            ))
+                            .help("only existing keywords are allowed in core/std")
+                            .emit();
+                        });
+                    }
+                }
+            }
+        }
+    }
+}

compiler/rustc_lint/src/lib.rs

@@ -463,6 +463,8 @@ fn register_internals(store: &mut LintStore) {
     store.register_early_pass(|| box DefaultHashTypes::new());
     store.register_lints(&LintPassImpl::get_lints());
     store.register_early_pass(|| box LintPassImpl);
+    store.register_lints(&ExistingDocKeyword::get_lints());
+    store.register_late_pass(|| box ExistingDocKeyword);
     store.register_lints(&TyTyKind::get_lints());
     store.register_late_pass(|| box TyTyKind);
     store.register_group(
@@ -475,6 +477,7 @@ fn register_internals(store: &mut LintStore) {
             LintId::of(LINT_PASS_IMPL_WITHOUT_MACRO),
             LintId::of(TY_PASS_BY_REFERENCE),
             LintId::of(USAGE_OF_QUALIFIED_TY),
+            LintId::of(EXISTING_DOC_KEYWORD),
         ],
     );
 }

compiler/rustc_mir/src/const_eval/machine.rs

@@ -7,6 +7,7 @@ use std::collections::hash_map::Entry;
 use std::hash::Hash;
 
 use rustc_data_structures::fx::FxHashMap;
+use std::fmt;
 
 use rustc_ast::Mutability;
 use rustc_hir::def_id::DefId;
@@ -179,6 +180,28 @@ impl<K: Hash + Eq, V> interpret::AllocMap<K, V> for FxHashMap<K, V> {
 crate type CompileTimeEvalContext<'mir, 'tcx> =
     InterpCx<'mir, 'tcx, CompileTimeInterpreter<'mir, 'tcx>>;
 
+#[derive(Debug, PartialEq, Eq, Copy, Clone)]
+pub enum MemoryKind {
+    Heap,
+}
+
+impl fmt::Display for MemoryKind {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            MemoryKind::Heap => write!(f, "heap allocation"),
+        }
+    }
+}
+
+impl interpret::MayLeak for MemoryKind {
+    #[inline(always)]
+    fn may_leak(self) -> bool {
+        match self {
+            MemoryKind::Heap => false,
+        }
+    }
+}
+
 impl interpret::MayLeak for ! {
     #[inline(always)]
     fn may_leak(self) -> bool {
@@ -222,6 +245,8 @@ impl<'mir, 'tcx: 'mir> CompileTimeEvalContext<'mir, 'tcx> {
 impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter<'mir, 'tcx> {
     compile_time_machine!(<'mir, 'tcx>);
 
+    type MemoryKind = MemoryKind;
+
     type MemoryExtra = MemoryExtra;
 
     fn find_mir_or_eval_fn(
@@ -317,7 +342,7 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter<'mir,
                 let ptr = ecx.memory.allocate(
                     Size::from_bytes(size as u64),
                     align,
-                    interpret::MemoryKind::ConstHeap,
+                    interpret::MemoryKind::Machine(MemoryKind::Heap),
                 );
                 ecx.write_scalar(Scalar::Ptr(ptr), dest)?;
             }

compiler/rustc_mir/src/interpret/intern.rs

@@ -25,19 +25,20 @@ use rustc_target::abi::Size;
 use rustc_ast::Mutability;
 
 use super::{AllocId, Allocation, InterpCx, MPlaceTy, Machine, MemoryKind, Scalar, ValueVisitor};
+use crate::const_eval;
 
-pub trait CompileTimeMachine<'mir, 'tcx> = Machine<
+pub trait CompileTimeMachine<'mir, 'tcx, T> = Machine<
     'mir,
     'tcx,
-    MemoryKind = !,
+    MemoryKind = T,
     PointerTag = (),
     ExtraFnVal = !,
     FrameExtra = (),
     AllocExtra = (),
-    MemoryMap = FxHashMap<AllocId, (MemoryKind<!>, Allocation)>,
+    MemoryMap = FxHashMap<AllocId, (MemoryKind<T>, Allocation)>,
 >;
 
-struct InternVisitor<'rt, 'mir, 'tcx, M: CompileTimeMachine<'mir, 'tcx>> {
+struct InternVisitor<'rt, 'mir, 'tcx, M: CompileTimeMachine<'mir, 'tcx, const_eval::MemoryKind>> {
     /// The ectx from which we intern.
     ecx: &'rt mut InterpCx<'mir, 'tcx, M>,
     /// Previously encountered safe references.
@@ -74,7 +75,7 @@ struct IsStaticOrFn;
 /// `immutable` things might become mutable if `ty` is not frozen.
 /// `ty` can be `None` if there is no potential interior mutability
 /// to account for (e.g. for vtables).
-fn intern_shallow<'rt, 'mir, 'tcx, M: CompileTimeMachine<'mir, 'tcx>>(
+fn intern_shallow<'rt, 'mir, 'tcx, M: CompileTimeMachine<'mir, 'tcx, const_eval::MemoryKind>>(
     ecx: &'rt mut InterpCx<'mir, 'tcx, M>,
     leftover_allocations: &'rt mut FxHashSet<AllocId>,
     alloc_id: AllocId,
@@ -105,7 +106,7 @@ fn intern_shallow<'rt, 'mir, 'tcx, M: CompileTimeMachine<'mir, 'tcx>>(
     // changes in this function.
     match kind {
         MemoryKind::Stack
-        | MemoryKind::ConstHeap
+        | MemoryKind::Machine(const_eval::MemoryKind::Heap)
         | MemoryKind::Vtable
         | MemoryKind::CallerLocation => {}
     }
@@ -141,7 +142,9 @@ fn intern_shallow<'rt, 'mir, 'tcx, M: CompileTimeMachine<'mir, 'tcx>>(
     None
 }
 
-impl<'rt, 'mir, 'tcx, M: CompileTimeMachine<'mir, 'tcx>> InternVisitor<'rt, 'mir, 'tcx, M> {
+impl<'rt, 'mir, 'tcx, M: CompileTimeMachine<'mir, 'tcx, const_eval::MemoryKind>>
+    InternVisitor<'rt, 'mir, 'tcx, M>
+{
     fn intern_shallow(
         &mut self,
         alloc_id: AllocId,
@@ -152,8 +155,8 @@ impl<'rt, 'mir, 'tcx, M: CompileTimeMachine<'mir, 'tcx>> InternVisitor<'rt, 'mir
     }
 }
 
-impl<'rt, 'mir, 'tcx: 'mir, M: CompileTimeMachine<'mir, 'tcx>> ValueVisitor<'mir, 'tcx, M>
-    for InternVisitor<'rt, 'mir, 'tcx, M>
+impl<'rt, 'mir, 'tcx: 'mir, M: CompileTimeMachine<'mir, 'tcx, const_eval::MemoryKind>>
+    ValueVisitor<'mir, 'tcx, M> for InternVisitor<'rt, 'mir, 'tcx, M>
 {
     type V = MPlaceTy<'tcx>;
 
@@ -290,7 +293,7 @@ pub enum InternKind {
 /// Any errors here would anyway be turned into `const_err` lints, whereas validation failures
 /// are hard errors.
 #[tracing::instrument(skip(ecx))]
-pub fn intern_const_alloc_recursive<M: CompileTimeMachine<'mir, 'tcx>>(
+pub fn intern_const_alloc_recursive<M: CompileTimeMachine<'mir, 'tcx, const_eval::MemoryKind>>(
     ecx: &mut InterpCx<'mir, 'tcx, M>,
     intern_kind: InternKind,
     ret: MPlaceTy<'tcx>,
@@ -421,7 +424,9 @@ where
     Ok(())
 }
 
-impl<'mir, 'tcx: 'mir, M: super::intern::CompileTimeMachine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
+impl<'mir, 'tcx: 'mir, M: super::intern::CompileTimeMachine<'mir, 'tcx, !>>
+    InterpCx<'mir, 'tcx, M>
+{
     /// A helper function that allocates memory for the layout given and gives you access to mutate
     /// it. Once your own mutation code is done, the backing `Allocation` is removed from the
     /// current `Memory` and returned.

compiler/rustc_mir/src/interpret/machine.rs

@@ -366,9 +366,9 @@ pub macro compile_time_machine(<$mir: lifetime, $tcx: lifetime>) {
     type PointerTag = ();
     type ExtraFnVal = !;
 
-    type MemoryKind = !;
-    type MemoryMap = rustc_data_structures::fx::FxHashMap<AllocId, (MemoryKind<!>, Allocation)>;
-    const GLOBAL_KIND: Option<!> = None; // no copying of globals from `tcx` to machine memory
+    type MemoryMap =
+        rustc_data_structures::fx::FxHashMap<AllocId, (MemoryKind<Self::MemoryKind>, Allocation)>;
+    const GLOBAL_KIND: Option<Self::MemoryKind> = None; // no copying of globals from `tcx` to machine memory
 
     type AllocExtra = ();
     type FrameExtra = ();
@@ -407,7 +407,7 @@ pub macro compile_time_machine(<$mir: lifetime, $tcx: lifetime>) {
         _memory_extra: &Self::MemoryExtra,
         _id: AllocId,
         alloc: Cow<'b, Allocation>,
-        _kind: Option<MemoryKind<!>>,
+        _kind: Option<MemoryKind<Self::MemoryKind>>,
     ) -> (Cow<'b, Allocation<Self::PointerTag>>, Self::PointerTag) {
         // We do not use a tag so we can just cheaply forward the allocation
         (alloc, ())

compiler/rustc_mir/src/interpret/memory.rs

@@ -27,9 +27,6 @@ use crate::util::pretty;
 pub enum MemoryKind<T> {
     /// Stack memory. Error if deallocated except during a stack pop.
     Stack,
-    /// Heap memory.
-    /// FIXME: this variant should be in const_eval
-    ConstHeap,
     /// Memory backing vtables. Error if ever deallocated.
     Vtable,
     /// Memory allocated by `caller_location` intrinsic. Error if ever deallocated.
@@ -43,7 +40,6 @@ impl<T: MayLeak> MayLeak for MemoryKind<T> {
     fn may_leak(self) -> bool {
         match self {
             MemoryKind::Stack => false,
-            MemoryKind::ConstHeap => false,
             MemoryKind::Vtable => true,
             MemoryKind::CallerLocation => true,
             MemoryKind::Machine(k) => k.may_leak(),
@@ -55,7 +51,6 @@ impl<T: fmt::Display> fmt::Display for MemoryKind<T> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
             MemoryKind::Stack => write!(f, "stack variable"),
-            MemoryKind::ConstHeap => write!(f, "heap allocation"),
             MemoryKind::Vtable => write!(f, "vtable"),
             MemoryKind::CallerLocation => write!(f, "caller location"),
             MemoryKind::Machine(m) => write!(f, "{}", m),

compiler/rustc_mir/src/transform/const_prop.rs

@@ -180,6 +180,8 @@ impl<'mir, 'tcx> ConstPropMachine<'mir, 'tcx> {
 impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for ConstPropMachine<'mir, 'tcx> {
     compile_time_machine!(<'mir, 'tcx>);
 
+    type MemoryKind = !;
+
     type MemoryExtra = ();
 
     fn find_mir_or_eval_fn(

library/alloc/tests/str.rs

@@ -1978,9 +1978,14 @@ fn const_str_ptr() {
     const B: &'static [u8; 2] = &A;
     const C: *const u8 = B as *const u8;
 
-    unsafe {
+    // Miri does not deduplicate consts (https://github.com/rust-lang/miri/issues/131)
+    #[cfg(not(miri))]
+    {
         let foo = &A as *const u8;
         assert_eq!(foo, C);
+    }
+
+    unsafe {
         assert_eq!(from_utf8_unchecked(&A), "hi");
         assert_eq!(*C, A[0]);
         assert_eq!(*(&B[0] as *const u8), A[0]);

library/core/src/fmt/mod.rs

@@ -403,7 +403,7 @@ impl<'a> Arguments<'a> {
     /// ```rust
     /// #![feature(fmt_as_str)]
     ///
-    /// use core::fmt::Arguments;
+    /// use std::fmt::Arguments;
     ///
     /// fn write_str(_: &str) { /* ... */ }
     ///

library/core/src/future/pending.rs

@@ -21,7 +21,7 @@ pub struct Pending<T> {
 /// # Examples
 ///
 /// ```no_run
-/// use core::future;
+/// use std::future;
 ///
 /// # async fn run() {
 /// let future = future::pending();

library/core/src/future/poll_fn.rs

@@ -3,7 +3,7 @@ use crate::future::Future;
 use crate::pin::Pin;
 use crate::task::{Context, Poll};
 
-/// Creates a future that wraps a function returning `Poll`.
+/// Creates a future that wraps a function returning [`Poll`].
 ///
 /// Polling the future delegates to the wrapped function.
 ///
@@ -13,7 +13,7 @@ use crate::task::{Context, Poll};
 /// #![feature(future_poll_fn)]
 /// # async fn run() {
 /// use core::future::poll_fn;
-/// use core::task::{Context, Poll};
+/// use std::task::{Context, Poll};
 ///
 /// fn read_line(_cx: &mut Context<'_>) -> Poll<String> {
 ///     Poll::Ready("Hello, World!".into())
@@ -31,7 +31,7 @@ where
     PollFn { f }
 }
 
-/// A Future that wraps a function returning `Poll`.
+/// A Future that wraps a function returning [`Poll`].
 ///
 /// This `struct` is created by [`poll_fn()`]. See its
 /// documentation for more.

library/core/src/future/ready.rs

@@ -33,7 +33,7 @@ impl<T> Future for Ready<T> {
 /// # Examples
 ///
 /// ```
-/// use core::future;
+/// use std::future;
 ///
 /// # async fn run() {
 /// let a = future::ready(1);

library/core/src/panic.rs

@@ -189,7 +189,7 @@ impl<'a> Location<'a> {
     /// # Examples
     ///
     /// ```
-    /// use core::panic::Location;
+    /// use std::panic::Location;
     ///
     /// /// Returns the [`Location`] at which it is called.
     /// #[track_caller]

library/core/src/task/ready.rs

@@ -1,15 +1,18 @@
-/// Extracts the successful type of a `Poll<T>`.
+/// Extracts the successful type of a [`Poll<T>`].
 ///
-/// This macro bakes in propagation of `Pending` signals by returning early.
+/// This macro bakes in propagation of [`Pending`] signals by returning early.
+///
+/// [`Poll<T>`]: crate::task::Poll
+/// [`Pending`]: crate::task::Poll::Pending
 ///
 /// # Examples
 ///
 /// ```
 /// #![feature(ready_macro)]
 ///
-/// use core::task::{ready, Context, Poll};
-/// use core::future::{self, Future};
-/// use core::pin::Pin;
+/// use std::task::{ready, Context, Poll};
+/// use std::future::{self, Future};
+/// use std::pin::Pin;
 ///
 /// pub fn do_poll(cx: &mut Context<'_>) -> Poll<()> {
 ///     let mut fut = future::ready(42);
@@ -28,9 +31,9 @@
 /// ```
 /// # #![feature(ready_macro)]
 /// #
-/// # use core::task::{Context, Poll};
-/// # use core::future::{self, Future};
-/// # use core::pin::Pin;
+/// # use std::task::{Context, Poll};
+/// # use std::future::{self, Future};
+/// # use std::pin::Pin;
 /// #
 /// # pub fn do_poll(cx: &mut Context<'_>) -> Poll<()> {
 ///     # let mut fut = future::ready(42);

library/std/src/lib.rs

@@ -212,6 +212,7 @@
     all(target_vendor = "fortanix", target_env = "sgx"),
     feature(slice_index_methods, coerce_unsized, sgx_platform)
 )]
+#![deny(rustc::existing_doc_keyword)]
 #![cfg_attr(all(test, target_vendor = "fortanix", target_env = "sgx"), feature(fixed_size_array))]
 // std is implemented with unstable features, many of which are internal
 // compiler details that will never be stable