-use crate::utils::{get_parent_expr, span_lint, span_lint_and_note};
+use clippy_utils::diagnostics::{span_lint, span_lint_and_note};
+use clippy_utils::{get_parent_expr, path_to_local, path_to_local_id};
use if_chain::if_chain;
-use rustc::hir::map::Map;
-use rustc::ty;
use rustc_hir::intravisit::{walk_expr, NestedVisitorMap, Visitor};
-use rustc_hir::{def, BinOpKind, Block, Expr, ExprKind, Guard, HirId, Local, Node, QPath, Stmt, StmtKind};
+use rustc_hir::{BinOpKind, Block, Expr, ExprKind, Guard, HirId, Local, Node, Stmt, StmtKind};
use rustc_lint::{LateContext, LateLintPass};
+use rustc_middle::hir::map::Map;
+use rustc_middle::ty;
use rustc_session::{declare_lint_pass, declare_tool_lint};
declare_clippy_lint! {
/// **Example:**
/// ```rust
/// let mut x = 0;
+ ///
+ /// // Bad
/// let a = {
/// x = 1;
/// 1
/// } + x;
/// // Unclear whether a is 1 or 2.
+ ///
+ /// // Good
+ /// let tmp = {
+ /// x = 1;
+ /// 1
+ /// };
+ /// let a = tmp + x;
/// ```
pub EVAL_ORDER_DEPENDENCE,
complexity,
declare_lint_pass!(EvalOrderDependence => [EVAL_ORDER_DEPENDENCE, DIVERGING_SUB_EXPRESSION]);
-impl<'a, 'tcx> LateLintPass<'a, 'tcx> for EvalOrderDependence {
- fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr<'_>) {
+impl<'tcx> LateLintPass<'tcx> for EvalOrderDependence {
+ fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
// Find a write to a local variable.
- match expr.kind {
- ExprKind::Assign(ref lhs, ..) | ExprKind::AssignOp(_, ref lhs, _) => {
- if let ExprKind::Path(ref qpath) = lhs.kind {
- if let QPath::Resolved(_, ref path) = *qpath {
- if path.segments.len() == 1 {
- if let def::Res::Local(var) = cx.tables.qpath_res(qpath, lhs.hir_id) {
- let mut visitor = ReadVisitor {
- cx,
- var,
- write_expr: expr,
- last_expr: expr,
- };
- check_for_unsequenced_reads(&mut visitor);
- }
- }
- }
- }
- },
- _ => {},
- }
+ let var = if_chain! {
+ if let ExprKind::Assign(lhs, ..) | ExprKind::AssignOp(_, lhs, _) = expr.kind;
+ if let Some(var) = path_to_local(lhs);
+ if expr.span.desugaring_kind().is_none();
+ then { var } else { return; }
+ };
+ let mut visitor = ReadVisitor {
+ cx,
+ var,
+ write_expr: expr,
+ last_expr: expr,
+ };
+ check_for_unsequenced_reads(&mut visitor);
}
- fn check_stmt(&mut self, cx: &LateContext<'a, 'tcx>, stmt: &'tcx Stmt<'_>) {
+ fn check_stmt(&mut self, cx: &LateContext<'tcx>, stmt: &'tcx Stmt<'_>) {
match stmt.kind {
- StmtKind::Local(ref local) => {
- if let Local { init: Some(ref e), .. } = **local {
+ StmtKind::Local(local) => {
+ if let Local { init: Some(e), .. } = local {
DivergenceVisitor { cx }.visit_expr(e);
}
},
- StmtKind::Expr(ref e) | StmtKind::Semi(ref e) => DivergenceVisitor { cx }.maybe_walk_expr(e),
+ StmtKind::Expr(e) | StmtKind::Semi(e) => DivergenceVisitor { cx }.maybe_walk_expr(e),
StmtKind::Item(..) => {},
}
}
}
struct DivergenceVisitor<'a, 'tcx> {
- cx: &'a LateContext<'a, 'tcx>,
+ cx: &'a LateContext<'tcx>,
}
impl<'a, 'tcx> DivergenceVisitor<'a, 'tcx> {
fn maybe_walk_expr(&mut self, e: &'tcx Expr<'_>) {
match e.kind {
ExprKind::Closure(..) => {},
- ExprKind::Match(ref e, arms, _) => {
+ ExprKind::Match(e, arms, _) => {
self.visit_expr(e);
for arm in arms {
if let Some(Guard::If(if_expr)) = arm.guard {
fn visit_expr(&mut self, e: &'tcx Expr<'_>) {
match e.kind {
ExprKind::Continue(_) | ExprKind::Break(_, _) | ExprKind::Ret(_) => self.report_diverging_sub_expr(e),
- ExprKind::Call(ref func, _) => {
- let typ = self.cx.tables.expr_ty(func);
- match typ.kind {
+ ExprKind::Call(func, _) => {
+ let typ = self.cx.typeck_results().expr_ty(func);
+ match typ.kind() {
ty::FnDef(..) | ty::FnPtr(_) => {
let sig = typ.fn_sig(self.cx.tcx);
- if let ty::Never = self.cx.tcx.erase_late_bound_regions(&sig).output().kind {
+ if let ty::Never = self.cx.tcx.erase_late_bound_regions(sig).output().kind() {
self.report_diverging_sub_expr(e);
}
},
}
},
ExprKind::MethodCall(..) => {
- let borrowed_table = self.cx.tables;
+ let borrowed_table = self.cx.typeck_results();
if borrowed_table.expr_ty(e).is_never() {
self.report_diverging_sub_expr(e);
}
fn check_stmt<'a, 'tcx>(vis: &mut ReadVisitor<'a, 'tcx>, stmt: &'tcx Stmt<'_>) -> StopEarly {
match stmt.kind {
- StmtKind::Expr(ref expr) | StmtKind::Semi(ref expr) => check_expr(vis, expr),
+ StmtKind::Expr(expr) | StmtKind::Semi(expr) => check_expr(vis, expr),
// If the declaration is of a local variable, check its initializer
// expression if it has one. Otherwise, keep going.
- StmtKind::Local(ref local) => local
+ StmtKind::Local(local) => local
.init
.as_ref()
.map_or(StopEarly::KeepGoing, |expr| check_expr(vis, expr)),
- _ => StopEarly::KeepGoing,
+ StmtKind::Item(..) => StopEarly::KeepGoing,
}
}
/// A visitor that looks for reads from a variable.
struct ReadVisitor<'a, 'tcx> {
- cx: &'a LateContext<'a, 'tcx>,
+ cx: &'a LateContext<'tcx>,
/// The ID of the variable we're looking for.
var: HirId,
/// The expressions where the write to the variable occurred (for reporting
return;
}
- match expr.kind {
- ExprKind::Path(ref qpath) => {
- if_chain! {
- if let QPath::Resolved(None, ref path) = *qpath;
- if path.segments.len() == 1;
- if let def::Res::Local(local_id) = self.cx.tables.qpath_res(qpath, expr.hir_id);
- if local_id == self.var;
- // Check that this is a read, not a write.
- if !is_in_assignment_position(self.cx, expr);
- then {
- span_lint_and_note(
- self.cx,
- EVAL_ORDER_DEPENDENCE,
- expr.span,
- "unsequenced read of a variable",
- self.write_expr.span,
- "whether read occurs before this write depends on evaluation order"
- );
- }
- }
+ if path_to_local_id(expr, self.var) {
+ // Check that this is a read, not a write.
+ if !is_in_assignment_position(self.cx, expr) {
+ span_lint_and_note(
+ self.cx,
+ EVAL_ORDER_DEPENDENCE,
+ expr.span,
+ &format!("unsequenced read of `{}`", self.cx.tcx.hir().name(self.var)),
+ Some(self.write_expr.span),
+ "whether read occurs before this write depends on evaluation order",
+ );
}
+ }
+ match expr.kind {
// We're about to descend a closure. Since we don't know when (or
// if) the closure will be evaluated, any reads in it might not
// occur here (or ever). Like above, bail to avoid false positives.
}
/// Returns `true` if `expr` is the LHS of an assignment, like `expr = ...`.
-fn is_in_assignment_position(cx: &LateContext<'_, '_>, expr: &Expr<'_>) -> bool {
+fn is_in_assignment_position(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
if let Some(parent) = get_parent_expr(cx, expr) {
- if let ExprKind::Assign(ref lhs, ..) = parent.kind {
+ if let ExprKind::Assign(lhs, ..) = parent.kind {
return lhs.hir_id == expr.hir_id;
}
}
projects / rust.git / blobdiff