use clippy_utils::ty::{is_type_diagnostic_item, peel_mid_ty_refs_is_mutable};
use clippy_utils::{
can_move_expr_to_closure, in_constant, is_else_clause, is_lang_ctor, is_lint_allowed, path_to_local_id,
- peel_hir_expr_refs,
+ peel_hir_expr_refs, peel_hir_expr_while, CaptureKind,
};
use rustc_ast::util::parser::PREC_POSTFIX;
use rustc_errors::Applicability;
use rustc_hir::LangItem::{OptionNone, OptionSome};
-use rustc_hir::{Arm, BindingAnnotation, Block, Expr, ExprKind, HirId, MatchSource, Mutability, Pat, PatKind};
+use rustc_hir::{
+ def::Res, Arm, BindingAnnotation, Block, Expr, ExprKind, HirId, MatchSource, Mutability, Pat, PatKind, Path, QPath,
+};
use rustc_lint::{LateContext, LateLintPass, LintContext};
use rustc_middle::lint::in_external_macro;
use rustc_session::{declare_lint_pass, declare_tool_lint};
return;
}
- if !can_move_expr_to_closure(cx, some_expr) {
- return;
- }
-
// Determine which binding mode to use.
let explicit_ref = some_pat.contains_explicit_ref_binding();
let binding_ref = explicit_ref.or_else(|| (ty_ref_count != pat_ref_count).then(|| ty_mutability));
None => "",
};
+ match can_move_expr_to_closure(cx, some_expr) {
+ Some(captures) => {
+ // Check if captures the closure will need conflict with borrows made in the scrutinee.
+ // TODO: check all the references made in the scrutinee expression. This will require interacting
+ // with the borrow checker. Currently only `<local>[.<field>]*` is checked for.
+ if let Some(binding_ref_mutability) = binding_ref {
+ let e = peel_hir_expr_while(scrutinee, |e| match e.kind {
+ ExprKind::Field(e, _) | ExprKind::AddrOf(_, _, e) => Some(e),
+ _ => None,
+ });
+ if let ExprKind::Path(QPath::Resolved(None, Path { res: Res::Local(l), .. })) = e.kind {
+ match captures.get(l) {
+ Some(CaptureKind::Value | CaptureKind::Ref(Mutability::Mut)) => return,
+ Some(CaptureKind::Ref(Mutability::Not))
+ if binding_ref_mutability == Mutability::Mut =>
+ {
+ return;
+ }
+ Some(CaptureKind::Ref(Mutability::Not)) | None => (),
+ }
+ }
+ }
+ },
+ None => return,
+ };
+
let mut app = Applicability::MachineApplicable;
// Remove address-of expressions from the scrutinee. Either `as_ref` will be called, or
use rustc_hir as hir;
use rustc_hir::def::{DefKind, Res};
use rustc_hir::def_id::DefId;
-use rustc_hir::hir_id::HirIdSet;
+use rustc_hir::hir_id::{HirIdMap, HirIdSet};
use rustc_hir::intravisit::{self, walk_expr, ErasedMap, FnKind, NestedVisitorMap, Visitor};
use rustc_hir::LangItem::{ResultErr, ResultOk};
use rustc_hir::{
def, Arm, BindingAnnotation, Block, Body, Constness, Destination, Expr, ExprKind, FnDecl, GenericArgs, HirId, Impl,
- ImplItem, ImplItemKind, IsAsync, Item, ItemKind, LangItem, Local, MatchSource, Node, Param, Pat, PatKind, Path,
- PathSegment, PrimTy, QPath, Stmt, StmtKind, TraitItem, TraitItemKind, TraitRef, TyKind, UnOp,
+ ImplItem, ImplItemKind, IsAsync, Item, ItemKind, LangItem, Local, MatchSource, Mutability, Node, Param, Pat,
+ PatKind, Path, PathSegment, PrimTy, QPath, Stmt, StmtKind, TraitItem, TraitItemKind, TraitRef, TyKind, UnOp,
};
use rustc_lint::{LateContext, Level, Lint, LintContext};
use rustc_middle::hir::exports::Export;
use rustc_middle::hir::map::Map;
use rustc_middle::ty as rustc_ty;
-use rustc_middle::ty::{layout::IntegerExt, DefIdTree, Ty, TyCtxt, TypeFoldable};
+use rustc_middle::ty::adjustment::{Adjust, Adjustment, AutoBorrow};
+use rustc_middle::ty::{layout::IntegerExt, DefIdTree, Ty, TyCtxt, TypeAndMut, TypeFoldable};
use rustc_semver::RustcVersion;
use rustc_session::Session;
use rustc_span::hygiene::{ExpnKind, MacroKind};
}
}
-/// Checks if the expression can be moved into a closure as is.
-pub fn can_move_expr_to_closure(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> bool {
+/// How a local is captured by a closure
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum CaptureKind {
+ Value,
+ Ref(Mutability),
+}
+impl std::ops::BitOr for CaptureKind {
+ type Output = Self;
+ fn bitor(self, rhs: Self) -> Self::Output {
+ match (self, rhs) {
+ (CaptureKind::Value, _) | (_, CaptureKind::Value) => CaptureKind::Value,
+ (CaptureKind::Ref(Mutability::Mut), CaptureKind::Ref(_))
+ | (CaptureKind::Ref(_), CaptureKind::Ref(Mutability::Mut)) => CaptureKind::Ref(Mutability::Mut),
+ (CaptureKind::Ref(Mutability::Not), CaptureKind::Ref(Mutability::Not)) => CaptureKind::Ref(Mutability::Not),
+ }
+ }
+}
+impl std::ops::BitOrAssign for CaptureKind {
+ fn bitor_assign(&mut self, rhs: Self) {
+ *self = *self | rhs;
+ }
+}
+
+/// Given an expression referencing a local, determines how it would be captured in a closure.
+/// Note as this will walk up to parent expressions until the capture can be determined it should
+/// only be used while making a closure somewhere a value is consumed. e.g. a block, match arm, or
+/// function argument (other than a receiver).
+pub fn capture_local_usage(cx: &LateContext<'tcx>, e: &Expr<'_>) -> CaptureKind {
+ debug_assert!(matches!(
+ e.kind,
+ ExprKind::Path(QPath::Resolved(None, Path { res: Res::Local(_), .. }))
+ ));
+
+ let map = cx.tcx.hir();
+ let mut child_id = e.hir_id;
+ let mut capture = CaptureKind::Value;
+
+ for (parent_id, parent) in map.parent_iter(e.hir_id) {
+ if let [Adjustment {
+ kind: Adjust::Deref(_) | Adjust::Borrow(AutoBorrow::Ref(..)),
+ target,
+ }, ref adjust @ ..] = *cx
+ .typeck_results()
+ .adjustments()
+ .get(child_id)
+ .map_or(&[][..], |x| &**x)
+ {
+ if let rustc_ty::RawPtr(TypeAndMut { mutbl: mutability, .. }) | rustc_ty::Ref(_, _, mutability) =
+ *adjust.last().map_or(target, |a| a.target).kind()
+ {
+ return CaptureKind::Ref(mutability);
+ }
+ }
+
+ if let Node::Expr(e) = parent {
+ match e.kind {
+ ExprKind::AddrOf(_, mutability, _) => return CaptureKind::Ref(mutability),
+ ExprKind::Index(..) | ExprKind::Unary(UnOp::Deref, _) => capture = CaptureKind::Ref(Mutability::Not),
+ ExprKind::Assign(lhs, ..) | ExprKind::Assign(_, lhs, _) if lhs.hir_id == child_id => {
+ return CaptureKind::Ref(Mutability::Mut);
+ },
+ _ => break,
+ }
+ } else {
+ break;
+ }
+
+ child_id = parent_id;
+ }
+
+ capture
+}
+
+/// Checks if the expression can be moved into a closure as is. This will return a list of captures
+/// if so, otherwise, `None`.
+pub fn can_move_expr_to_closure(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<HirIdMap<CaptureKind>> {
struct V<'cx, 'tcx> {
cx: &'cx LateContext<'tcx>,
// Stack of potential break targets contained in the expression.
locals: HirIdSet,
/// Whether this expression can be turned into a closure.
allow_closure: bool,
+ /// Locals which need to be captured, and whether they need to be by value, reference, or
+ /// mutable reference.
+ captures: HirIdMap<CaptureKind>,
}
impl Visitor<'tcx> for V<'_, 'tcx> {
type Map = ErasedMap<'tcx>;
if !self.allow_closure {
return;
}
- if let ExprKind::Loop(b, ..) = e.kind {
- self.loops.push(e.hir_id);
- self.visit_block(b);
- self.loops.pop();
- } else {
- self.allow_closure &= can_move_expr_to_closure_no_visit(self.cx, e, &self.loops, &self.locals);
- walk_expr(self, e);
+
+ match e.kind {
+ ExprKind::Path(QPath::Resolved(None, &Path { res: Res::Local(l), .. })) => {
+ if !self.locals.contains(&l) {
+ let cap = capture_local_usage(self.cx, e);
+ self.captures.entry(l).and_modify(|e| *e |= cap).or_insert(cap);
+ }
+ },
+ ExprKind::Loop(b, ..) => {
+ self.loops.push(e.hir_id);
+ self.visit_block(b);
+ self.loops.pop();
+ },
+ _ => {
+ self.allow_closure &= can_move_expr_to_closure_no_visit(self.cx, e, &self.loops, &self.locals);
+ walk_expr(self, e);
+ },
}
}
allow_closure: true,
loops: Vec::new(),
locals: HirIdSet::default(),
+ captures: HirIdMap::default(),
};
v.visit_expr(expr);
- v.allow_closure
+ v.allow_closure.then(|| v.captures)
}
/// Returns the method names and argument list of nested method call expressions that make up
projects / rust.git / commitdiff