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Auto merge of #7174 - camsteffen:eval-order-async, r=flip1995

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Fix eval_order_dependence async false positive

changelog: Fix [`eval_order_dependence`] false positive in async code

Fixes #6925
This commit is contained in:
bors 2021-05-05 21:18:05 +00:00
commit 93fe3562d0
3 changed files with 33 additions and 27 deletions
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16
clippy_lints/src/eval_order_dependence.rs
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@ -1,5 +1,6 @@
use clippy_utils::diagnostics::{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 clippy_utils::{get_parent_expr, path_to_local, path_to_local_id};
use if_chain::if_chain;
use rustc_hir::intravisit::{walk_expr, NestedVisitorMap, Visitor}; use rustc_hir::intravisit::{walk_expr, NestedVisitorMap, Visitor};
use rustc_hir::{BinOpKind, Block, Expr, ExprKind, Guard, HirId, Local, Node, Stmt, StmtKind}; use rustc_hir::{BinOpKind, Block, Expr, ExprKind, Guard, HirId, Local, Node, Stmt, StmtKind};
use rustc_lint::{LateContext, LateLintPass}; use rustc_lint::{LateContext, LateLintPass};
@ -70,9 +71,12 @@ declare_lint_pass!(EvalOrderDependence => [EVAL_ORDER_DEPENDENCE, DIVERGING_SUB_
impl<'tcx> LateLintPass<'tcx> for EvalOrderDependence { impl<'tcx> LateLintPass<'tcx> for EvalOrderDependence {
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) { fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
// Find a write to a local variable. // Find a write to a local variable.
match expr.kind { let var = if_chain! {
ExprKind::Assign(lhs, ..) | ExprKind::AssignOp(_, lhs, _) => { if let ExprKind::Assign(lhs, ..) | ExprKind::AssignOp(_, lhs, _) = expr.kind;
if let Some(var) = path_to_local(lhs) { if let Some(var) = path_to_local(lhs);
if expr.span.desugaring_kind().is_none();
then { var } else { return; }
};
let mut visitor = ReadVisitor { let mut visitor = ReadVisitor {
cx, cx,
var, var,
@ -81,10 +85,6 @@ impl<'tcx> LateLintPass<'tcx> for EvalOrderDependence {
}; };
check_for_unsequenced_reads(&mut visitor); check_for_unsequenced_reads(&mut visitor);
} }
},
_ => {},
}
}
fn check_stmt(&mut self, cx: &LateContext<'tcx>, stmt: &'tcx Stmt<'_>) { fn check_stmt(&mut self, cx: &LateContext<'tcx>, stmt: &'tcx Stmt<'_>) {
match stmt.kind { match stmt.kind {
StmtKind::Local(local) => { StmtKind::Local(local) => {
@ -305,7 +305,7 @@ impl<'a, 'tcx> Visitor<'tcx> for ReadVisitor<'a, 'tcx> {
self.cx, self.cx,
EVAL_ORDER_DEPENDENCE, EVAL_ORDER_DEPENDENCE,
expr.span, expr.span,
"unsequenced read of a variable", &format!("unsequenced read of `{}`", self.cx.tcx.hir().name(self.var)),
Some(self.write_expr.span), Some(self.write_expr.span),
"whether read occurs before this write depends on evaluation order", "whether read occurs before this write depends on evaluation order",
); );

6
tests/ui/eval_order_dependence.rs
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@ -1,3 +1,5 @@
// edition:2018
#[warn(clippy::eval_order_dependence)] #[warn(clippy::eval_order_dependence)]
#[allow( #[allow(
unused_assignments, unused_assignments,
@ -107,3 +109,7 @@ fn main() {
}, },
); );
} }
async fn issue_6925() {
let _ = vec![async { true }.await, async { false }.await];
}

24
tests/ui/eval_order_dependence.stderr
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@ -1,48 +1,48 @@
error: unsequenced read of a variable error: unsequenced read of `x`
--> $DIR/eval_order_dependence.rs:15:9 --> $DIR/eval_order_dependence.rs:17:9
| |
LL | } + x; LL | } + x;
| ^ | ^
| |
= note: `-D clippy::eval-order-dependence` implied by `-D warnings` = note: `-D clippy::eval-order-dependence` implied by `-D warnings`
note: whether read occurs before this write depends on evaluation order note: whether read occurs before this write depends on evaluation order
--> $DIR/eval_order_dependence.rs:13:9 --> $DIR/eval_order_dependence.rs:15:9
| |
LL | x = 1; LL | x = 1;
| ^^^^^ | ^^^^^
error: unsequenced read of a variable error: unsequenced read of `x`
--> $DIR/eval_order_dependence.rs:18:5 --> $DIR/eval_order_dependence.rs:20:5
| |
LL | x += { LL | x += {
| ^ | ^
| |
note: whether read occurs before this write depends on evaluation order note: whether read occurs before this write depends on evaluation order
--> $DIR/eval_order_dependence.rs:19:9 --> $DIR/eval_order_dependence.rs:21:9
| |
LL | x = 20; LL | x = 20;
| ^^^^^^ | ^^^^^^
error: unsequenced read of a variable error: unsequenced read of `x`
--> $DIR/eval_order_dependence.rs:31:12 --> $DIR/eval_order_dependence.rs:33:12
| |
LL | a: x, LL | a: x,
| ^ | ^
| |
note: whether read occurs before this write depends on evaluation order note: whether read occurs before this write depends on evaluation order
--> $DIR/eval_order_dependence.rs:33:13 --> $DIR/eval_order_dependence.rs:35:13
| |
LL | x = 6; LL | x = 6;
| ^^^^^ | ^^^^^
error: unsequenced read of a variable error: unsequenced read of `x`
--> $DIR/eval_order_dependence.rs:40:9 --> $DIR/eval_order_dependence.rs:42:9
| |
LL | x += { LL | x += {
| ^ | ^
| |
note: whether read occurs before this write depends on evaluation order note: whether read occurs before this write depends on evaluation order
--> $DIR/eval_order_dependence.rs:41:13 --> $DIR/eval_order_dependence.rs:43:13
| |
LL | x = 20; LL | x = 20;
| ^^^^^^ | ^^^^^^