X-Git-Url: https://git.lizzy.rs/?a=blobdiff_plain;f=clippy_utils%2Fsrc%2Flib.rs;h=b40b42fa6d3b610d817056d448bc22347335ce63;hb=5e4d8b44f9524f28fd1ebca18f48ecad204cf184;hp=00db52a9457d85d50b30fb15da254764a55aa835;hpb=4c41a222ca5d1325fb4b6709395bd06e766cc042;p=rust.git diff --git a/clippy_utils/src/lib.rs b/clippy_utils/src/lib.rs index 00db52a9457..b40b42fa6d3 100644 --- a/clippy_utils/src/lib.rs +++ b/clippy_utils/src/lib.rs @@ -62,23 +62,27 @@ use std::hash::BuildHasherDefault; use if_chain::if_chain; -use rustc_ast::ast::{self, Attribute, BorrowKind, LitKind}; +use rustc_ast::ast::{self, Attribute, LitKind}; use rustc_data_structures::unhash::UnhashMap; use rustc_hir as hir; use rustc_hir::def::{DefKind, Res}; use rustc_hir::def_id::DefId; +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, 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::hir::place::PlaceBase; 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::binding::BindingMode; +use rustc_middle::ty::{layout::IntegerExt, BorrowKind, DefIdTree, Ty, TyCtxt, TypeAndMut, TypeFoldable, UpvarCapture}; use rustc_semver::RustcVersion; use rustc_session::Session; use rustc_span::hygiene::{ExpnKind, MacroKind}; @@ -89,7 +93,7 @@ use rustc_target::abi::Integer; use crate::consts::{constant, Constant}; -use crate::ty::{can_partially_move_ty, is_recursively_primitive_type}; +use crate::ty::{can_partially_move_ty, is_copy, is_recursively_primitive_type}; pub fn parse_msrv(msrv: &str, sess: Option<&Session>, span: Option) -> Option { if let Ok(version) = RustcVersion::parse(msrv) { @@ -326,6 +330,25 @@ pub fn is_trait_method(cx: &LateContext<'_>, expr: &Expr<'_>, diag_item: Symbol) .map_or(false, |did| is_diag_trait_item(cx, did, diag_item)) } +/// Checks if the given expression is a path referring an item on the trait +/// that is marked with the given diagnostic item. +/// +/// For checking method call expressions instead of path expressions, use +/// [`is_trait_method`]. +/// +/// For example, this can be used to find if an expression like `u64::default` +/// refers to an item of the trait `Default`, which is associated with the +/// `diag_item` of `sym::Default`. +pub fn is_trait_item(cx: &LateContext<'_>, expr: &Expr<'_>, diag_item: Symbol) -> bool { + if let hir::ExprKind::Path(ref qpath) = expr.kind { + cx.qpath_res(qpath, expr.hir_id) + .opt_def_id() + .map_or(false, |def_id| is_diag_trait_item(cx, def_id, diag_item)) + } else { + false + } +} + pub fn last_path_segment<'tcx>(path: &QPath<'tcx>) -> &'tcx PathSegment<'tcx> { match *path { QPath::Resolved(_, path) => path.segments.last().expect("A path must have at least one segment"), @@ -411,12 +434,22 @@ pub fn is_qpath_def_path(cx: &LateContext<'_>, path: &QPath<'_>, hir_id: HirId, } /// If the expression is a path, resolves it to a `DefId` and checks if it matches the given path. +/// +/// Please use `is_expr_diagnostic_item` if the target is a diagnostic item. pub fn is_expr_path_def_path(cx: &LateContext<'_>, expr: &Expr<'_>, segments: &[&str]) -> bool { expr_path_res(cx, expr) .opt_def_id() .map_or(false, |id| match_def_path(cx, id, segments)) } +/// If the expression is a path, resolves it to a `DefId` and checks if it matches the given +/// diagnostic item. +pub fn is_expr_diagnostic_item(cx: &LateContext<'_>, expr: &Expr<'_>, diag_item: Symbol) -> bool { + expr_path_res(cx, expr) + .opt_def_id() + .map_or(false, |id| cx.tcx.is_diagnostic_item(diag_item, id)) +} + /// THIS METHOD IS DEPRECATED and will eventually be removed since it does not match against the /// entire path or resolved `DefId`. Prefer using `match_def_path`. Consider getting a `DefId` from /// `QPath::Resolved.1.res.opt_def_id()`. @@ -480,6 +513,9 @@ fn item_child_by_name<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId, name: &str) -> Opt let (krate, first, path) = match *path { [krate, first, ref path @ ..] => (krate, first, path), + [primitive] => { + return PrimTy::from_name(Symbol::intern(primitive)).map_or(Res::Err, Res::PrimTy); + }, _ => return Res::Err, }; let tcx = cx.tcx; @@ -545,12 +581,95 @@ pub fn trait_ref_of_method<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Optio None } +/// This method will return tuple of projection stack and root of the expression, +/// used in `can_mut_borrow_both`. +/// +/// For example, if `e` represents the `v[0].a.b[x]` +/// this method will return a tuple, composed of a `Vec` +/// containing the `Expr`s for `v[0], v[0].a, v[0].a.b, v[0].a.b[x]` +/// and a `Expr` for root of them, `v` +fn projection_stack<'a, 'hir>(mut e: &'a Expr<'hir>) -> (Vec<&'a Expr<'hir>>, &'a Expr<'hir>) { + let mut result = vec![]; + let root = loop { + match e.kind { + ExprKind::Index(ep, _) | ExprKind::Field(ep, _) => { + result.push(e); + e = ep; + }, + _ => break e, + }; + }; + result.reverse(); + (result, root) +} + +/// Checks if two expressions can be mutably borrowed simultaneously +/// and they aren't dependent on borrowing same thing twice +pub fn can_mut_borrow_both(cx: &LateContext<'_>, e1: &Expr<'_>, e2: &Expr<'_>) -> bool { + let (s1, r1) = projection_stack(e1); + let (s2, r2) = projection_stack(e2); + if !eq_expr_value(cx, r1, r2) { + return true; + } + for (x1, x2) in s1.iter().zip(s2.iter()) { + match (&x1.kind, &x2.kind) { + (ExprKind::Field(_, i1), ExprKind::Field(_, i2)) => { + if i1 != i2 { + return true; + } + }, + (ExprKind::Index(_, i1), ExprKind::Index(_, i2)) => { + if !eq_expr_value(cx, i1, i2) { + return false; + } + }, + _ => return false, + } + } + false +} + /// Checks if the top level expression can be moved into a closure as is. -pub fn can_move_expr_to_closure_no_visit(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>, jump_targets: &[HirId]) -> bool { +/// Currently checks for: +/// * Break/Continue outside the given loop HIR ids. +/// * Yield/Return statments. +/// * Inline assembly. +/// * Usages of a field of a local where the type of the local can be partially moved. +/// +/// For example, given the following function: +/// +/// ``` +/// fn f<'a>(iter: &mut impl Iterator) { +/// for item in iter { +/// let s = item.1; +/// if item.0 > 10 { +/// continue; +/// } else { +/// s.clear(); +/// } +/// } +/// } +/// ``` +/// +/// When called on the expression `item.0` this will return false unless the local `item` is in the +/// `ignore_locals` set. The type `(usize, &mut String)` can have the second element moved, so it +/// isn't always safe to move into a closure when only a single field is needed. +/// +/// When called on the `continue` expression this will return false unless the outer loop expression +/// is in the `loop_ids` set. +/// +/// Note that this check is not recursive, so passing the `if` expression will always return true +/// even though sub-expressions might return false. +pub fn can_move_expr_to_closure_no_visit( + cx: &LateContext<'tcx>, + expr: &'tcx Expr<'_>, + loop_ids: &[HirId], + ignore_locals: &HirIdSet, +) -> bool { match expr.kind { ExprKind::Break(Destination { target_id: Ok(id), .. }, _) | ExprKind::Continue(Destination { target_id: Ok(id), .. }) - if jump_targets.contains(&id) => + if loop_ids.contains(&id) => { true }, @@ -562,25 +681,156 @@ pub fn can_move_expr_to_closure_no_visit(cx: &LateContext<'tcx>, expr: &'tcx Exp | ExprKind::LlvmInlineAsm(_) => false, // Accessing a field of a local value can only be done if the type isn't // partially moved. - ExprKind::Field(base_expr, _) - if matches!( - base_expr.kind, - ExprKind::Path(QPath::Resolved(_, Path { res: Res::Local(_), .. })) - ) && can_partially_move_ty(cx, cx.typeck_results().expr_ty(base_expr)) => - { + ExprKind::Field( + &Expr { + hir_id, + kind: + ExprKind::Path(QPath::Resolved( + _, + Path { + res: Res::Local(local_id), + .. + }, + )), + .. + }, + _, + ) if !ignore_locals.contains(local_id) && can_partially_move_ty(cx, cx.typeck_results().node_type(hir_id)) => { // TODO: check if the local has been partially moved. Assume it has for now. false - } + }, _ => true, } } -/// 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 { + fn pat_capture_kind(cx: &LateContext<'_>, pat: &Pat<'_>) -> CaptureKind { + let mut capture = CaptureKind::Ref(Mutability::Not); + pat.each_binding(|_, id, span, _| { + match cx.typeck_results().extract_binding_mode(cx.sess(), id, span).unwrap() { + BindingMode::BindByValue(_) if !is_copy(cx, cx.typeck_results().node_type(id)) => { + capture = CaptureKind::Value; + }, + BindingMode::BindByReference(Mutability::Mut) if capture != CaptureKind::Value => { + capture = CaptureKind::Ref(Mutability::Mut); + }, + _ => (), + } + }); + capture + } + + 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; + let mut capture_expr_ty = e; + + 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); + } + } + + match parent { + Node::Expr(e) => 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); + }, + ExprKind::Field(..) => { + if capture == CaptureKind::Value { + capture_expr_ty = e; + } + }, + ExprKind::Match(_, arms, _) => { + let mut mutability = Mutability::Not; + for capture in arms.iter().map(|arm| pat_capture_kind(cx, arm.pat)) { + match capture { + CaptureKind::Value => break, + CaptureKind::Ref(Mutability::Mut) => mutability = Mutability::Mut, + CaptureKind::Ref(Mutability::Not) => (), + } + } + return CaptureKind::Ref(mutability); + }, + _ => break, + }, + Node::Local(l) => match pat_capture_kind(cx, l.pat) { + CaptureKind::Value => break, + capture @ CaptureKind::Ref(_) => return capture, + }, + _ => break, + } + + child_id = parent_id; + } + + if capture == CaptureKind::Value && is_copy(cx, cx.typeck_results().expr_ty(capture_expr_ty)) { + // Copy types are never automatically captured by value. + CaptureKind::Ref(Mutability::Not) + } else { + 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> { struct V<'cx, 'tcx> { cx: &'cx LateContext<'tcx>, + // Stack of potential break targets contained in the expression. loops: Vec, + /// Local variables created in the expression. These don't need to be captured. + 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, } impl Visitor<'tcx> for V<'_, 'tcx> { type Map = ErasedMap<'tcx>; @@ -592,24 +842,67 @@ fn visit_expr(&mut self, e: &'tcx Expr<'_>) { 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); - 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::Closure(..) => { + let closure_id = self.cx.tcx.hir().local_def_id(e.hir_id).to_def_id(); + for capture in self.cx.typeck_results().closure_min_captures_flattened(closure_id) { + let local_id = match capture.place.base { + PlaceBase::Local(id) => id, + PlaceBase::Upvar(var) => var.var_path.hir_id, + _ => continue, + }; + if !self.locals.contains(&local_id) { + let capture = match capture.info.capture_kind { + UpvarCapture::ByValue(_) => CaptureKind::Value, + UpvarCapture::ByRef(borrow) => match borrow.kind { + BorrowKind::ImmBorrow => CaptureKind::Ref(Mutability::Not), + BorrowKind::UniqueImmBorrow | BorrowKind::MutBorrow => { + CaptureKind::Ref(Mutability::Mut) + }, + }, + }; + self.captures + .entry(local_id) + .and_modify(|e| *e |= capture) + .or_insert(capture); + } + } + }, + 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); + }, } } + + fn visit_pat(&mut self, p: &'tcx Pat<'tcx>) { + p.each_binding_or_first(&mut |_, id, _, _| { + self.locals.insert(id); + }); + } } let mut v = V { cx, 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 @@ -1231,6 +1524,8 @@ pub fn match_function_call<'tcx>( /// Checks if the given `DefId` matches any of the paths. Returns the index of matching path, if /// any. +/// +/// Please use `match_any_diagnostic_items` if the targets are all diagnostic items. pub fn match_any_def_paths(cx: &LateContext<'_>, did: DefId, paths: &[&[&str]]) -> Option { let search_path = cx.get_def_path(did); paths @@ -1238,6 +1533,14 @@ pub fn match_any_def_paths(cx: &LateContext<'_>, did: DefId, paths: &[&[&str]]) .position(|p| p.iter().map(|x| Symbol::intern(x)).eq(search_path.iter().copied())) } +/// Checks if the given `DefId` matches any of provided diagnostic items. Returns the index of +/// matching path, if any. +pub fn match_any_diagnostic_items(cx: &LateContext<'_>, def_id: DefId, diag_items: &[Symbol]) -> Option { + diag_items + .iter() + .position(|item| cx.tcx.is_diagnostic_item(*item, def_id)) +} + /// Checks if the given `DefId` matches the path. pub fn match_def_path<'tcx>(cx: &LateContext<'tcx>, did: DefId, syms: &[&str]) -> bool { // We should probably move to Symbols in Clippy as well rather than interning every time. @@ -1625,7 +1928,7 @@ pub fn peel_hir_expr_while<'tcx>( pub fn peel_n_hir_expr_refs(expr: &'a Expr<'a>, count: usize) -> (&'a Expr<'a>, usize) { let mut remaining = count; let e = peel_hir_expr_while(expr, |e| match e.kind { - ExprKind::AddrOf(BorrowKind::Ref, _, e) if remaining != 0 => { + ExprKind::AddrOf(ast::BorrowKind::Ref, _, e) if remaining != 0 => { remaining -= 1; Some(e) }, @@ -1639,7 +1942,7 @@ pub fn peel_n_hir_expr_refs(expr: &'a Expr<'a>, count: usize) -> (&'a Expr<'a>, pub fn peel_hir_expr_refs(expr: &'a Expr<'a>) -> (&'a Expr<'a>, usize) { let mut count = 0; let e = peel_hir_expr_while(expr, |e| match e.kind { - ExprKind::AddrOf(BorrowKind::Ref, _, e) => { + ExprKind::AddrOf(ast::BorrowKind::Ref, _, e) => { count += 1; Some(e) },