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Skip the mutation in while body case for closures

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flip1995 2018-03-26 12:32:21 +02:00
parent d458f22d89
commit 7d29075132
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GPG key ID: 852B722799AB5978
2 changed files with 37 additions and 37 deletions
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38
clippy_lints/src/loops.rs
View file

@ -347,7 +347,9 @@ declare_lint! {
/// **Why is this bad?** If the condition is unchanged, entering the body of the loop
/// will lead to an infinite loop.
///
/// **Known problems:** None
/// **Known problems:** If the `while`-loop is in a closure, the check for mutation of the
/// condition variables in the body can cause false negatives. For example when only `Upvar` `a` is
/// in the condition and only `Upvar` `b` gets mutated in the body, the lint will not trigger.
///
/// **Example:**
/// ```rust
@ -2150,17 +2152,6 @@ fn check_infinite_loop<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, cond: &'tcx Expr, b
return;
}
if mut_var_visitor.ids.is_empty() {
span_lint(
cx,
WHILE_IMMUTABLE_CONDITION,
cond.span,
"all variables in condition are immutable. This either leads to an infinite or to a never running loop.",
);
return;
}
let mut delegate = MutVarsDelegate {
used_mutably: mut_var_visitor.ids,
skip: false,
@ -2169,6 +2160,9 @@ fn check_infinite_loop<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, cond: &'tcx Expr, b
let region_scope_tree = &cx.tcx.region_scope_tree(def_id);
ExprUseVisitor::new(&mut delegate, cx.tcx, cx.param_env, region_scope_tree, cx.tables, None).walk_expr(expr);
if delegate.skip {
return;
}
if !delegate.used_mutably.iter().any(|(_, v)| *v) {
span_lint(
cx,
@ -2195,9 +2189,13 @@ impl<'a, 'tcx> VarCollectorVisitor<'a, 'tcx> {
if let ExprPath(ref qpath) = ex.node;
if let QPath::Resolved(None, _) = *qpath;
let def = self.cx.tables.qpath_def(qpath, ex.hir_id);
if let Def::Local(node_id) = def;
then {
self.ids.insert(node_id, false);
match def {
Def::Local(node_id) | Def::Upvar(node_id, ..) => {
self.ids.insert(node_id, false);
},
_ => {},
}
}
}
}
@ -2206,10 +2204,7 @@ impl<'a, 'tcx> VarCollectorVisitor<'a, 'tcx> {
impl<'a, 'tcx> Visitor<'tcx> for VarCollectorVisitor<'a, 'tcx> {
fn visit_expr(&mut self, ex: &'tcx Expr) {
match ex.node {
ExprPath(_) => if let Some(node_id) = check_for_mutability(self.cx, ex) {
self.ids.insert(node_id, false);
},
ExprPath(_) => self.insert_def_id(ex),
// If there is any fuction/method call… we just stop analysis
ExprCall(..) | ExprMethodCall(..) => self.skip = true,
@ -2236,7 +2231,12 @@ impl<'tcx> MutVarsDelegate {
if let Some(used) = self.used_mutably.get_mut(&id) {
*used = true;
},
Categorization::Upvar(_) => skip = true,
Categorization::Upvar(_) => {
//FIXME: This causes false negatives. We can't get the `NodeId` from
//`Categorization::Upvar(_)`. So we search for any `Upvar`s in the
//`while`-body, not just the ones in the condition.
self.skip = true
},
Categorization::Deref(ref cmt, _) => self.update(&cmt.cat, sp),
_ => {}
}

36
tests/ui/infinite_loop.stderr
View file

@ -1,57 +1,57 @@
error: Variable in the condition are not mutated in the loop body. This either leads to an infinite or to a never running loop.
--> $DIR/infinite_loop.rs:10:11
--> $DIR/infinite_loop.rs:14:11
|
10 | while y < 10 {
14 | while y < 10 {
| ^^^^^^
|
= note: `-D while-immutable-condition` implied by `-D warnings`
error: Variable in the condition are not mutated in the loop body. This either leads to an infinite or to a never running loop.
--> $DIR/infinite_loop.rs:15:11
--> $DIR/infinite_loop.rs:19:11
|
15 | while y < 10 && x < 3 {
19 | while y < 10 && x < 3 {
| ^^^^^^^^^^^^^^^
error: Variable in the condition are not mutated in the loop body. This either leads to an infinite or to a never running loop.
--> $DIR/infinite_loop.rs:22:11
--> $DIR/infinite_loop.rs:26:11
|
22 | while !cond {
26 | while !cond {
| ^^^^^
error: Variable in the condition are not mutated in the loop body. This either leads to an infinite or to a never running loop.
--> $DIR/infinite_loop.rs:52:11
--> $DIR/infinite_loop.rs:64:11
|
52 | while i < 3 {
64 | while i < 3 {
| ^^^^^
error: Variable in the condition are not mutated in the loop body. This either leads to an infinite or to a never running loop.
--> $DIR/infinite_loop.rs:57:11
--> $DIR/infinite_loop.rs:69:11
|
57 | while i < 3 && j > 0 {
69 | while i < 3 && j > 0 {
| ^^^^^^^^^^^^^^
error: Variable in the condition are not mutated in the loop body. This either leads to an infinite or to a never running loop.
--> $DIR/infinite_loop.rs:61:11
--> $DIR/infinite_loop.rs:73:11
|
61 | while i < 3 {
73 | while i < 3 {
| ^^^^^
error: Variable in the condition are not mutated in the loop body. This either leads to an infinite or to a never running loop.
--> $DIR/infinite_loop.rs:76:11
--> $DIR/infinite_loop.rs:88:11
|
76 | while i < 3 {
88 | while i < 3 {
| ^^^^^
error: Variable in the condition are not mutated in the loop body. This either leads to an infinite or to a never running loop.
--> $DIR/infinite_loop.rs:81:11
--> $DIR/infinite_loop.rs:93:11
|
81 | while i < 3 {
93 | while i < 3 {
| ^^^^^
error: Variable in the condition are not mutated in the loop body. This either leads to an infinite or to a never running loop.
--> $DIR/infinite_loop.rs:144:15
--> $DIR/infinite_loop.rs:156:15
|
144 | while self.count < n {
156 | while self.count < n {
| ^^^^^^^^^^^^^^
error: aborting due to 9 previous errors