since: $ver,
issue: to_nonzero($issue),
edition: $edition,
- description: concat!($($doc,)*),
}
),+];
/// Allows specifying the as-needed link modifier
(active, native_link_modifiers_as_needed, "1.53.0", Some(81490), None),
- /// Allows unnamed fields of struct and union type
- (incomplete, unnamed_fields, "1.53.0", Some(49804), None),
-
/// Allows qualified paths in struct expressions, struct patterns and tuple struct patterns.
(active, more_qualified_paths, "1.54.0", Some(86935), None),
/// Allows `let...else` statements.
(active, let_else, "1.56.0", Some(87335), None),
+ /// Allows the `#[must_not_suspend]` attribute.
+ (active, must_not_suspend, "1.57.0", Some(83310), None),
+
+
// -------------------------------------------------------------------------
// feature-group-end: actual feature gates
// -------------------------------------------------------------------------
ungated!(forbid, Normal, template!(List: r#"lint1, lint2, ..., /*opt*/ reason = "...""#)),
ungated!(deny, Normal, template!(List: r#"lint1, lint2, ..., /*opt*/ reason = "...""#)),
ungated!(must_use, Normal, template!(Word, NameValueStr: "reason")),
+ gated!(
+ must_not_suspend, Normal, template!(Word, NameValueStr: "reason"), must_not_suspend,
+ experimental!(must_not_suspend)
+ ),
// FIXME(#14407)
ungated!(
deprecated, Normal,
),
// Enumerates "identity-like" conversion methods to suggest on type mismatch.
rustc_attr!(rustc_conversion_suggestion, Normal, template!(Word), INTERNAL_UNSTABLE),
+ // Prevents field reads in the marked trait or method to be considered
+ // during dead code analysis.
+ rustc_attr!(rustc_trivial_field_reads, Normal, template!(Word), INTERNAL_UNSTABLE),
// ==========================================================================
// Internal attributes, Const related:
"imports that are never used"
}
+ declare_lint! {
+ /// The `must_not_suspend` lint guards against values that shouldn't be held across suspend points
+ /// (`.await`)
+ ///
+ /// ### Example
+ ///
+ /// ```rust
+ /// #![feature(must_not_suspend)]
+ ///
+ /// #[must_not_suspend]
+ /// struct SyncThing {}
+ ///
+ /// async fn yield_now() {}
+ ///
+ /// pub async fn uhoh() {
+ /// let guard = SyncThing {};
+ /// yield_now().await;
+ /// }
+ /// ```
+ ///
+ /// {{produces}}
+ ///
+ /// ### Explanation
+ ///
+ /// The `must_not_suspend` lint detects values that are marked with the `#[must_not_suspend]`
+ /// attribute being held across suspend points. A "suspend" point is usually a `.await` in an async
+ /// function.
+ ///
+ /// This attribute can be used to mark values that are semantically incorrect across suspends
+ /// (like certain types of timers), values that have async alternatives, and values that
+ /// regularly cause problems with the `Send`-ness of async fn's returned futures (like
+ /// `MutexGuard`'s)
+ ///
+ pub MUST_NOT_SUSPEND,
+ Warn,
+ "use of a `#[must_not_suspend]` value across a yield point",
+ }
+
declare_lint! {
/// The `unused_extern_crates` lint guards against `extern crate` items
/// that are never used.
///
/// ### Example
///
- /// ```rust
+ /// ```rust,edition2018
/// trait Trait { }
///
/// fn takes_trait_object(_: Box<Trait>) {
CENUM_IMPL_DROP_CAST,
CONST_EVALUATABLE_UNCHECKED,
INEFFECTIVE_UNSTABLE_TRAIT_IMPL,
+ MUST_NOT_SUSPEND,
UNINHABITED_STATIC,
FUNCTION_ITEM_REFERENCES,
USELESS_DEPRECATED,
UNSUPPORTED_CALLING_CONVENTIONS,
BREAK_WITH_LABEL_AND_LOOP,
UNUSED_ATTRIBUTES,
+ NON_EXHAUSTIVE_OMITTED_PATTERNS,
]
}
///
/// ### Example
///
- /// ```rust,compile_fail
+ /// ```rust,edition2018,compile_fail
/// #![deny(rust_2021_prefixes_incompatible_syntax)]
///
/// macro_rules! m {
///
/// This lint suggests to add whitespace between the `z` and `"hey"` tokens
/// to keep them separated in Rust 2021.
+ // Allow this lint -- rustdoc doesn't yet support threading edition into this lint's parser.
+ #[allow(rustdoc::invalid_rust_codeblocks)]
pub RUST_2021_PREFIXES_INCOMPATIBLE_SYNTAX,
Allow,
"identifiers that will be parsed as a prefix in Rust 2021",
Warn,
"`break` expression with label and unlabeled loop as value expression"
}
+
+declare_lint! {
+ /// The `non_exhaustive_omitted_patterns` lint detects when a wildcard (`_` or `..`) in a
+ /// pattern for a `#[non_exhaustive]` struct or enum is reachable.
+ ///
+ /// ### Example
+ ///
+ /// ```rust,ignore (needs separate crate)
+ /// // crate A
+ /// #[non_exhaustive]
+ /// pub enum Bar {
+ /// A,
+ /// B, // added variant in non breaking change
+ /// }
+ ///
+ /// // in crate B
+ /// match Bar::A {
+ /// Bar::A => {},
+ /// #[warn(non_exhaustive_omitted_patterns)]
+ /// _ => {},
+ /// }
+ /// ```
+ ///
+ /// This will produce:
+ ///
+ /// ```text
+ /// warning: reachable patterns not covered of non exhaustive enum
+ /// --> $DIR/reachable-patterns.rs:70:9
+ /// |
+ /// LL | _ => {}
+ /// | ^ pattern `B` not covered
+ /// |
+ /// note: the lint level is defined here
+ /// --> $DIR/reachable-patterns.rs:69:16
+ /// |
+ /// LL | #[warn(non_exhaustive_omitted_patterns)]
+ /// | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+ /// = help: ensure that all possible cases are being handled by adding the suggested match arms
+ /// = note: the matched value is of type `Bar` and the `non_exhaustive_omitted_patterns` attribute was found
+ /// ```
+ ///
+ /// ### Explanation
+ ///
+ /// Structs and enums tagged with `#[non_exhaustive]` force the user to add a
+ /// (potentially redundant) wildcard when pattern-matching, to allow for future
+ /// addition of fields or variants. The `non_exhaustive_omitted_patterns` lint
+ /// detects when such a wildcard happens to actually catch some fields/variants.
+ /// In other words, when the match without the wildcard would not be exhaustive.
+ /// This lets the user be informed if new fields/variants were added.
+ pub NON_EXHAUSTIVE_OMITTED_PATTERNS,
+ Allow,
+ "detect when patterns of types marked `non_exhaustive` are missed",
+}
use rustc_arena::DroplessArena;
use rustc_data_structures::fx::FxHashMap;
use rustc_data_structures::stable_hasher::{HashStable, StableHasher, ToStableHashKey};
+use rustc_data_structures::sync::Lock;
use rustc_macros::HashStable_Generic;
use rustc_serialize::{Decodable, Decoder, Encodable, Encoder};
mul,
mul_assign,
mul_with_overflow,
+ must_not_suspend,
must_use,
mut_ptr,
mut_slice_ptr,
panic_2021,
panic_abort,
panic_bounds_check,
+ panic_display,
panic_fmt,
panic_handler,
panic_impl,
panic_unwind,
panicking,
param_attrs,
- parent_trait,
partial_cmp,
partial_ord,
passes,
rustc_synthetic,
rustc_test_marker,
rustc_then_this_would_need,
+ rustc_trivial_field_reads,
rustc_unsafe_specialization_marker,
rustc_variance,
rustdoc,
simd_select_bitmask,
simd_shl,
simd_shr,
+ simd_shuffle,
simd_sub,
simd_trunc,
simd_xor,
unix,
unlikely,
unmarked_api,
- unnamed_fields,
unpin,
unreachable,
unreachable_code,
wrapping_sub,
wreg,
write_bytes,
+ write_str,
x87_reg,
xer,
xmm_reg,
/// Maps a string to its interned representation.
pub fn intern(string: &str) -> Self {
- with_interner(|interner| interner.intern(string))
+ with_session_globals(|session_globals| session_globals.symbol_interner.intern(string))
}
/// Convert to a `SymbolStr`. This is a slowish operation because it
/// requires locking the symbol interner.
pub fn as_str(self) -> SymbolStr {
- with_interner(|interner| unsafe {
- SymbolStr { string: std::mem::transmute::<&str, &str>(interner.get(self)) }
+ with_session_globals(|session_globals| {
+ let symbol_str = session_globals.symbol_interner.get(self);
+ unsafe { SymbolStr { string: std::mem::transmute::<&str, &str>(symbol_str) } }
})
}
}
pub fn len(self) -> usize {
- with_interner(|interner| interner.get(self).len())
+ with_session_globals(|session_globals| session_globals.symbol_interner.get(self).len())
}
pub fn is_empty(self) -> bool {
}
}
+#[derive(Default)]
+pub(crate) struct Interner(Lock<InternerInner>);
+
// The `&'static str`s in this type actually point into the arena.
//
// The `FxHashMap`+`Vec` pair could be replaced by `FxIndexSet`, but #75278
// found that to regress performance up to 2% in some cases. This might be
// revisited after further improvements to `indexmap`.
+//
+// This type is private to prevent accidentally constructing more than one `Interner` on the same
+// thread, which makes it easy to mixup `Symbol`s between `Interner`s.
#[derive(Default)]
-pub struct Interner {
+struct InternerInner {
arena: DroplessArena,
names: FxHashMap<&'static str, Symbol>,
strings: Vec<&'static str>,
impl Interner {
fn prefill(init: &[&'static str]) -> Self {
- Interner {
+ Interner(Lock::new(InternerInner {
strings: init.into(),
names: init.iter().copied().zip((0..).map(Symbol::new)).collect(),
..Default::default()
- }
+ }))
}
#[inline]
- pub fn intern(&mut self, string: &str) -> Symbol {
- if let Some(&name) = self.names.get(string) {
+ fn intern(&self, string: &str) -> Symbol {
+ let mut inner = self.0.lock();
+ if let Some(&name) = inner.names.get(string) {
return name;
}
- let name = Symbol::new(self.strings.len() as u32);
+ let name = Symbol::new(inner.strings.len() as u32);
// `from_utf8_unchecked` is safe since we just allocated a `&str` which is known to be
// UTF-8.
let string: &str =
- unsafe { str::from_utf8_unchecked(self.arena.alloc_slice(string.as_bytes())) };
+ unsafe { str::from_utf8_unchecked(inner.arena.alloc_slice(string.as_bytes())) };
// It is safe to extend the arena allocation to `'static` because we only access
// these while the arena is still alive.
let string: &'static str = unsafe { &*(string as *const str) };
- self.strings.push(string);
- self.names.insert(string, name);
+ inner.strings.push(string);
+ inner.names.insert(string, name);
name
}
// Get the symbol as a string. `Symbol::as_str()` should be used in
// preference to this function.
- pub fn get(&self, symbol: Symbol) -> &str {
- self.strings[symbol.0.as_usize()]
+ fn get(&self, symbol: Symbol) -> &str {
+ self.0.lock().strings[symbol.0.as_usize()]
}
}
}
}
-#[inline]
-fn with_interner<T, F: FnOnce(&mut Interner) -> T>(f: F) -> T {
- with_session_globals(|session_globals| f(&mut *session_globals.symbol_interner.lock()))
-}
-
/// An alternative to [`Symbol`], useful when the chars within the symbol need to
/// be accessed. It deliberately has limited functionality and should only be
/// used for temporary values.
//! This calculates the types which has storage which lives across a suspension point in a
//! generator from the perspective of typeck. The actual types used at runtime
-//! is calculated in `rustc_mir::transform::generator` and may be a subset of the
+//! is calculated in `rustc_const_eval::transform::generator` and may be a subset of the
//! types computed here.
use super::FnCtxt;
use rustc_data_structures::fx::{FxHashSet, FxIndexSet};
+ use rustc_errors::pluralize;
use rustc_hir as hir;
use rustc_hir::def::{CtorKind, DefKind, Res};
use rustc_hir::def_id::DefId;
use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
use rustc_hir::{Arm, Expr, ExprKind, Guard, HirId, Pat, PatKind};
use rustc_middle::middle::region::{self, YieldData};
- use rustc_middle::ty::{self, Ty};
+ use rustc_middle::ty::{self, Ty, TyCtxt};
+ use rustc_span::symbol::sym;
use rustc_span::Span;
use smallvec::SmallVec;
+ use tracing::debug;
struct InteriorVisitor<'a, 'tcx> {
fcx: &'a FnCtxt<'a, 'tcx>,
/// that they may succeed the said yield point in the post-order.
guard_bindings: SmallVec<[SmallVec<[HirId; 4]>; 1]>,
guard_bindings_set: HirIdSet,
+ linted_values: HirIdSet,
}
impl<'a, 'tcx> InteriorVisitor<'a, 'tcx> {
fn record(
&mut self,
ty: Ty<'tcx>,
+ hir_id: HirId,
scope: Option<region::Scope>,
expr: Option<&'tcx Expr<'tcx>>,
source_span: Span,
} else {
// Insert the type into the ordered set.
let scope_span = scope.map(|s| s.span(self.fcx.tcx, self.region_scope_tree));
+
+ if !self.linted_values.contains(&hir_id) {
+ check_must_not_suspend_ty(
+ self.fcx,
+ ty,
+ hir_id,
+ SuspendCheckData {
+ expr,
+ source_span,
+ yield_span: yield_data.span,
+ plural_len: 1,
+ ..Default::default()
+ },
+ );
+ self.linted_values.insert(hir_id);
+ }
+
self.types.insert(ty::GeneratorInteriorTypeCause {
span: source_span,
ty: &ty,
prev_unresolved_span: None,
guard_bindings: <_>::default(),
guard_bindings_set: <_>::default(),
+ linted_values: <_>::default(),
};
intravisit::walk_body(&mut visitor, body);
if let PatKind::Binding(..) = pat.kind {
let scope = self.region_scope_tree.var_scope(pat.hir_id.local_id);
let ty = self.fcx.typeck_results.borrow().pat_ty(pat);
- self.record(ty, Some(scope), None, pat.span, false);
+ self.record(ty, pat.hir_id, Some(scope), None, pat.span, false);
}
}
// If there are adjustments, then record the final type --
// this is the actual value that is being produced.
if let Some(adjusted_ty) = self.fcx.typeck_results.borrow().expr_ty_adjusted_opt(expr) {
- self.record(adjusted_ty, scope, Some(expr), expr.span, guard_borrowing_from_pattern);
+ self.record(
+ adjusted_ty,
+ expr.hir_id,
+ scope,
+ Some(expr),
+ expr.span,
+ guard_borrowing_from_pattern,
+ );
}
// Also record the unadjusted type (which is the only type if
tcx.mk_region(ty::RegionKind::ReErased),
ty::TypeAndMut { ty, mutbl: hir::Mutability::Not },
);
- self.record(ref_ty, scope, Some(expr), expr.span, guard_borrowing_from_pattern);
+ self.record(
+ ref_ty,
+ expr.hir_id,
+ scope,
+ Some(expr),
+ expr.span,
+ guard_borrowing_from_pattern,
+ );
}
- self.record(ty, scope, Some(expr), expr.span, guard_borrowing_from_pattern);
+ self.record(
+ ty,
+ expr.hir_id,
+ scope,
+ Some(expr),
+ expr.span,
+ guard_borrowing_from_pattern,
+ );
} else {
self.fcx.tcx.sess.delay_span_bug(expr.span, "no type for node");
}
}
}
}
+
+ #[derive(Default)]
+ pub struct SuspendCheckData<'a, 'tcx> {
+ expr: Option<&'tcx Expr<'tcx>>,
+ source_span: Span,
+ yield_span: Span,
+ descr_pre: &'a str,
+ descr_post: &'a str,
+ plural_len: usize,
+ }
+
+ // Returns whether it emitted a diagnostic or not
+ // Note that this fn and the proceding one are based on the code
+ // for creating must_use diagnostics
+ //
+ // Note that this technique was chosen over things like a `Suspend` marker trait
+ // as it is simpler and has precendent in the compiler
+ pub fn check_must_not_suspend_ty<'tcx>(
+ fcx: &FnCtxt<'_, 'tcx>,
+ ty: Ty<'tcx>,
+ hir_id: HirId,
+ data: SuspendCheckData<'_, 'tcx>,
+ ) -> bool {
+ if ty.is_unit()
+ // FIXME: should this check `is_ty_uninhabited_from`. This query is not available in this stage
+ // of typeck (before ReVar and RePlaceholder are removed), but may remove noise, like in
+ // `must_use`
+ // || fcx.tcx.is_ty_uninhabited_from(fcx.tcx.parent_module(hir_id).to_def_id(), ty, fcx.param_env)
+ {
+ return false;
+ }
+
+ let plural_suffix = pluralize!(data.plural_len);
+
+ match *ty.kind() {
+ ty::Adt(..) if ty.is_box() => {
+ let boxed_ty = ty.boxed_ty();
+ let descr_pre = &format!("{}boxed ", data.descr_pre);
+ check_must_not_suspend_ty(fcx, boxed_ty, hir_id, SuspendCheckData { descr_pre, ..data })
+ }
+ ty::Adt(def, _) => check_must_not_suspend_def(fcx.tcx, def.did, hir_id, data),
+ // FIXME: support adding the attribute to TAITs
+ ty::Opaque(def, _) => {
+ let mut has_emitted = false;
+ for &(predicate, _) in fcx.tcx.explicit_item_bounds(def) {
+ // We only look at the `DefId`, so it is safe to skip the binder here.
+ if let ty::PredicateKind::Trait(ref poly_trait_predicate) =
+ predicate.kind().skip_binder()
+ {
+ let def_id = poly_trait_predicate.trait_ref.def_id;
+ let descr_pre = &format!("{}implementer{} of ", data.descr_pre, plural_suffix);
+ if check_must_not_suspend_def(
+ fcx.tcx,
+ def_id,
+ hir_id,
+ SuspendCheckData { descr_pre, ..data },
+ ) {
+ has_emitted = true;
+ break;
+ }
+ }
+ }
+ has_emitted
+ }
+ ty::Dynamic(binder, _) => {
+ let mut has_emitted = false;
+ for predicate in binder.iter() {
+ if let ty::ExistentialPredicate::Trait(ref trait_ref) = predicate.skip_binder() {
+ let def_id = trait_ref.def_id;
+ let descr_post = &format!(" trait object{}{}", plural_suffix, data.descr_post);
+ if check_must_not_suspend_def(
+ fcx.tcx,
+ def_id,
+ hir_id,
+ SuspendCheckData { descr_post, ..data },
+ ) {
+ has_emitted = true;
+ break;
+ }
+ }
+ }
+ has_emitted
+ }
+ ty::Tuple(ref tys) => {
+ let mut has_emitted = false;
+ let spans = if let Some(hir::ExprKind::Tup(comps)) = data.expr.map(|e| &e.kind) {
+ debug_assert_eq!(comps.len(), tys.len());
+ comps.iter().map(|e| e.span).collect()
+ } else {
+ vec![]
+ };
+ for (i, ty) in tys.iter().map(|k| k.expect_ty()).enumerate() {
+ let descr_post = &format!(" in tuple element {}", i);
+ let span = *spans.get(i).unwrap_or(&data.source_span);
+ if check_must_not_suspend_ty(
+ fcx,
+ ty,
+ hir_id,
+ SuspendCheckData { descr_post, source_span: span, ..data },
+ ) {
+ has_emitted = true;
+ }
+ }
+ has_emitted
+ }
+ ty::Array(ty, len) => {
+ let descr_pre = &format!("{}array{} of ", data.descr_pre, plural_suffix);
+ check_must_not_suspend_ty(
+ fcx,
+ ty,
+ hir_id,
+ SuspendCheckData {
+ descr_pre,
+ plural_len: len.try_eval_usize(fcx.tcx, fcx.param_env).unwrap_or(0) as usize
+ + 1,
+ ..data
+ },
+ )
+ }
+ _ => false,
+ }
+ }
+
+ fn check_must_not_suspend_def(
+ tcx: TyCtxt<'_>,
+ def_id: DefId,
+ hir_id: HirId,
+ data: SuspendCheckData<'_, '_>,
+ ) -> bool {
+ for attr in tcx.get_attrs(def_id).iter() {
+ if attr.has_name(sym::must_not_suspend) {
+ tcx.struct_span_lint_hir(
+ rustc_session::lint::builtin::MUST_NOT_SUSPEND,
+ hir_id,
+ data.source_span,
+ |lint| {
+ let msg = format!(
+ "{}`{}`{} held across a suspend point, but should not be",
+ data.descr_pre,
+ tcx.def_path_str(def_id),
+ data.descr_post,
+ );
+ let mut err = lint.build(&msg);
+
+ // add span pointing to the offending yield/await
+ err.span_label(data.yield_span, "the value is held across this suspend point");
+
+ // Add optional reason note
+ if let Some(note) = attr.value_str() {
+ // FIXME(guswynn): consider formatting this better
+ err.span_note(data.source_span, ¬e.as_str());
+ }
+
+ // Add some quick suggestions on what to do
+ // FIXME: can `drop` work as a suggestion here as well?
+ err.span_help(
+ data.source_span,
+ "consider using a block (`{ ... }`) \
+ to shrink the value's scope, ending before the suspend point",
+ );
+
+ err.emit();
+ },
+ );
+
+ return true;
+ }
+ }
+ false
+ }
projects / rust.git / commitdiff