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Fix needless_range_loop bad suggestion

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Detect if the index variable is used inside a closure.

Fixes #2542
This commit is contained in:
Michael Wright 2019-02-11 07:03:12 +02:00
parent bd23cb89ec
commit 217965e855
3 changed files with 39 additions and 8 deletions
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30
clippy_lints/src/loops.rs
View file

@ -1830,17 +1830,29 @@ impl<'a, 'tcx> Visitor<'tcx> for VarVisitor<'a, 'tcx> {
if let ExprKind::Path(ref qpath) = expr.node;
if let QPath::Resolved(None, ref path) = *qpath;
if path.segments.len() == 1;
if let Def::Local(local_id) = self.cx.tables.qpath_def(qpath, expr.hir_id);
then {
if local_id == self.var {
// we are not indexing anything, record that
self.nonindex = true;
} else {
// not the correct variable, but still a variable
self.referenced.insert(path.segments[0].ident.name);
match self.cx.tables.qpath_def(qpath, expr.hir_id) {
Def::Upvar(local_id, ..) => {
if local_id == self.var {
// we are not indexing anything, record that
self.nonindex = true;
}
}
Def::Local(local_id) =>
{
if local_id == self.var {
self.nonindex = true;
} else {
// not the correct variable, but still a variable
self.referenced.insert(path.segments[0].ident.name);
}
}
_ => {}
}
}
}
let old = self.prefer_mutable;
match expr.node {
ExprKind::AssignOp(_, ref lhs, ref rhs) | ExprKind::Assign(ref lhs, ref rhs) => {
@ -1880,6 +1892,10 @@ impl<'a, 'tcx> Visitor<'tcx> for VarVisitor<'a, 'tcx> {
self.visit_expr(expr);
}
},
ExprKind::Closure(_, _, body_id, ..) => {
let body = self.cx.tcx.hir().body(body_id);
self.visit_expr(&body.value);
},
_ => walk_expr(self, expr),
}
self.prefer_mutable = old;

5
tests/ui/needless_range_loop.rs
View file

@ -80,4 +80,9 @@ fn main() {
for i in 1..3 {
println!("{}", arr[i]);
}
// #2542
for i in 0..vec.len() {
vec[i] = Some(1).unwrap_or_else(|| panic!("error on {}", i));
}
}

12
tests/ui/needless_range_loop.stderr
View file

@ -80,5 +80,15 @@ help: consider using an iterator
LL | for <item> in arr.iter().skip(1) {
| ^^^^^^ ^^^^^^^^^^^^^^^^^^
error: aborting due to 8 previous errors
error: the loop variable `i` is used to index `vec`
--> $DIR/needless_range_loop.rs:85:14
|
LL | for i in 0..vec.len() {
| ^^^^^^^^^^^^
help: consider using an iterator
|
LL | for (i, <item>) in vec.iter_mut().enumerate() {
| ^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^
error: aborting due to 9 previous errors