#![feature(in_band_lifetimes)]
#![feature(iter_zip)]
#![feature(rustc_private)]
+#![feature(control_flow_enum)]
#![recursion_limit = "512"]
#![cfg_attr(feature = "deny-warnings", deny(warnings))]
#![allow(clippy::missing_errors_doc, clippy::missing_panics_doc, clippy::must_use_candidate)]
extern crate rustc_ast;
extern crate rustc_ast_pretty;
extern crate rustc_attr;
+extern crate rustc_const_eval;
extern crate rustc_data_structures;
extern crate rustc_errors;
extern crate rustc_hir;
extern crate rustc_lexer;
extern crate rustc_lint;
extern crate rustc_middle;
-extern crate rustc_mir;
extern crate rustc_session;
extern crate rustc_span;
extern crate rustc_target;
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::LangItem::{OptionNone, 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, Mutability, Node, Param, Pat,
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::adjustment::{Adjust, Adjustment, AutoBorrow};
-use rustc_middle::ty::{layout::IntegerExt, DefIdTree, Ty, TyCtxt, TypeAndMut, TypeFoldable};
+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};
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<Span>) -> Option<RustcVersion> {
if let Ok(version) = RustcVersion::parse(msrv) {
}
}
+pub fn is_unit_expr(expr: &Expr<'_>) -> bool {
+ matches!(
+ expr.kind,
+ ExprKind::Block(
+ Block {
+ stmts: [],
+ expr: None,
+ ..
+ },
+ _
+ ) | ExprKind::Tup([])
+ )
+}
+
/// Checks if given pattern is a wildcard (`_`)
pub fn is_wild(pat: &Pat<'_>) -> bool {
matches!(pat.kind, PatKind::Wild)
}
};
}
- fn item_child_by_name<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId, name: &str) -> Option<&'tcx Export<HirId>> {
+ fn item_child_by_name<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId, name: &str) -> Option<&'tcx Export> {
tcx.item_children(def_id)
.iter()
.find(|item| item.ident.name.as_str() == name)
None
}
});
- try_res!(last).res
+ try_res!(last).res.expect_non_local()
}
/// Convenience function to get the `DefId` of a trait by path.
/// 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`
+/// and an `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 {
false
}
+/// Returns true if the `def_id` associated with the `path` is recognized as a "default-equivalent"
+/// constructor from the std library
+fn is_default_equivalent_ctor(cx: &LateContext<'_>, def_id: DefId, path: &QPath<'_>) -> bool {
+ let std_types_symbols = &[
+ sym::string_type,
+ sym::vec_type,
+ sym::vecdeque_type,
+ sym::LinkedList,
+ sym::hashmap_type,
+ sym::BTreeMap,
+ sym::hashset_type,
+ sym::BTreeSet,
+ sym::BinaryHeap,
+ ];
+
+ if let QPath::TypeRelative(_, method) = path {
+ if method.ident.name == sym::new {
+ if let Some(impl_did) = cx.tcx.impl_of_method(def_id) {
+ if let Some(adt) = cx.tcx.type_of(impl_did).ty_adt_def() {
+ return std_types_symbols
+ .iter()
+ .any(|&symbol| cx.tcx.is_diagnostic_item(symbol, adt.did));
+ }
+ }
+ }
+ }
+ false
+}
+
+/// Returns true if the expr is equal to `Default::default()` of it's type when evaluated.
+/// It doesn't cover all cases, for example indirect function calls (some of std
+/// functions are supported) but it is the best we have.
+pub fn is_default_equivalent(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
+ match &e.kind {
+ ExprKind::Lit(lit) => match lit.node {
+ LitKind::Bool(false) | LitKind::Int(0, _) => true,
+ LitKind::Str(s, _) => s.is_empty(),
+ _ => false,
+ },
+ ExprKind::Tup(items) | ExprKind::Array(items) => items.iter().all(|x| is_default_equivalent(cx, x)),
+ ExprKind::Repeat(x, _) => is_default_equivalent(cx, x),
+ ExprKind::Call(repl_func, _) => if_chain! {
+ if let ExprKind::Path(ref repl_func_qpath) = repl_func.kind;
+ if let Some(repl_def_id) = cx.qpath_res(repl_func_qpath, repl_func.hir_id).opt_def_id();
+ if is_diag_trait_item(cx, repl_def_id, sym::Default)
+ || is_default_equivalent_ctor(cx, repl_def_id, repl_func_qpath);
+ then {
+ true
+ }
+ else {
+ false
+ }
+ },
+ ExprKind::Path(qpath) => is_lang_ctor(cx, qpath, OptionNone),
+ ExprKind::AddrOf(rustc_hir::BorrowKind::Ref, _, expr) => matches!(expr.kind, ExprKind::Array([])),
+ _ => false,
+ }
+}
+
/// Checks if the top level expression can be moved into a closure as is.
+/// 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<Item = (usize, &'a mut String)>) {
+/// 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<'_>,
- jump_targets: &[HirId],
+ 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
},
Value,
Ref(Mutability),
}
+impl CaptureKind {
+ pub fn is_imm_ref(self) -> bool {
+ self == Self::Ref(Mutability::Not)
+ }
+}
impl std::ops::BitOr for CaptureKind {
type Output = Self;
fn bitor(self, rhs: Self) -> Self::Output {
/// 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_or_first(&mut |_, 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) {
+ for (parent_id, parent) in cx.tcx.hir().parent_iter(e.hir_id) {
if let [Adjustment {
kind: Adjust::Deref(_) | Adjust::Borrow(AutoBorrow::Ref(..)),
target,
}
}
- if let Node::Expr(e) = parent {
- match e.kind {
+ 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::Let(pat, ..) => {
+ let mutability = match pat_capture_kind(cx, pat) {
+ CaptureKind::Value => Mutability::Not,
+ CaptureKind::Ref(m) => m,
+ };
+ return CaptureKind::Ref(mutability);
+ },
+ 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,
- }
- } else {
- break;
+ },
+ Node::Local(l) => match pat_capture_kind(cx, l.pat) {
+ CaptureKind::Value => break,
+ capture @ CaptureKind::Ref(_) => return capture,
+ },
+ _ => break,
}
child_id = parent_id;
}
- capture
+ 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
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);
let source_map_and_line = cx.sess().source_map().lookup_line(span.lo()).unwrap();
let line_no = source_map_and_line.line;
let line_start = source_map_and_line.sf.lines[line_no];
- Span::new(line_start, span.hi(), span.ctxt())
+ span.with_lo(line_start)
}
/// Gets the parent node, if any.
/// Gets the loop or closure enclosing the given expression, if any.
pub fn get_enclosing_loop_or_closure(tcx: TyCtxt<'tcx>, expr: &Expr<'_>) -> Option<&'tcx Expr<'tcx>> {
- let map = tcx.hir();
- for (_, node) in map.parent_iter(expr.hir_id) {
+ for (_, node) in tcx.hir().parent_iter(expr.hir_id) {
match node {
Node::Expr(
e
/// Gets the parent node if it's an impl block.
pub fn get_parent_as_impl(tcx: TyCtxt<'_>, id: HirId) -> Option<&Impl<'_>> {
- let map = tcx.hir();
- match map.parent_iter(id).next() {
+ match tcx.hir().parent_iter(id).next() {
Some((
_,
Node::Item(Item {
/// Checks if the given expression is the else clause of either an `if` or `if let` expression.
pub fn is_else_clause(tcx: TyCtxt<'_>, expr: &Expr<'_>) -> bool {
- let map = tcx.hir();
- let mut iter = map.parent_iter(expr.hir_id);
+ let mut iter = tcx.hir().parent_iter(expr.hir_id);
match iter.next() {
- Some((arm_id, Node::Arm(..))) => matches!(
- iter.next(),
- Some((
- _,
- Node::Expr(Expr {
- kind: ExprKind::Match(_, [_, else_arm], MatchSource::IfLetDesugar { .. }),
- ..
- })
- ))
- if else_arm.hir_id == arm_id
- ),
Some((
_,
Node::Expr(Expr {
let mut conds = Vec::new();
let mut blocks: Vec<&Block<'_>> = Vec::new();
- while let ExprKind::If(cond, then_expr, ref else_expr) = expr.kind {
- conds.push(cond);
- if let ExprKind::Block(block, _) = then_expr.kind {
+ while let Some(higher::IfOrIfLet { cond, then, r#else }) = higher::IfOrIfLet::hir(expr) {
+ conds.push(&*cond);
+ if let ExprKind::Block(block, _) = then.kind {
blocks.push(block);
} else {
panic!("ExprKind::If node is not an ExprKind::Block");
}
- if let Some(else_expr) = *else_expr {
+ if let Some(else_expr) = r#else {
expr = else_expr;
} else {
break;
/// Gets the node where an expression is either used, or it's type is unified with another branch.
pub fn get_expr_use_or_unification_node(tcx: TyCtxt<'tcx>, expr: &Expr<'_>) -> Option<Node<'tcx>> {
- let map = tcx.hir();
let mut child_id = expr.hir_id;
- let mut iter = map.parent_iter(child_id);
+ let mut iter = tcx.hir().parent_iter(child_id);
loop {
match iter.next() {
None => break None,
.predicates_of(did)
.predicates
.iter()
- .filter_map(|(p, _)| if p.is_global() { Some(*p) } else { None });
+ .filter_map(|(p, _)| if p.is_global(cx.tcx) { Some(*p) } else { None });
traits::impossible_predicates(
cx.tcx,
traits::elaborate_predicates(cx.tcx, predicates)
if is_primitive {
// if we have wrappers like Array, Slice or Tuple, print these
// and get the type enclosed in the slice ref
- match expr_type.peel_refs().walk().nth(1).unwrap().expect_ty().kind() {
+ match expr_type.peel_refs().walk(cx.tcx).nth(1).unwrap().expect_ty().kind() {
rustc_ty::Slice(..) => return Some("slice".into()),
rustc_ty::Array(..) => return Some("array".into()),
rustc_ty::Tuple(..) => return Some("tuple".into()),
// is_recursively_primitive_type() should have taken care
// of the rest and we can rely on the type that is found
let refs_peeled = expr_type.peel_refs();
- return Some(refs_peeled.walk().last().unwrap().to_string());
+ return Some(refs_peeled.walk(cx.tcx).last().unwrap().to_string());
},
}
}
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)
},
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)
},