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Fix FP in same_item_push #5997

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merged 2 commits into from
Sep 5, 2020
Merged

Fix FP in same_item_push #5997

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aa7ffa5
Fix FP in `same_item_push`
giraffate Sep 1, 2020
96b31a5
Fix FP when coercion kicks in
giraffate Sep 5, 2020
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79 changes: 44 additions & 35 deletions clippy_lints/src/loops.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1140,43 +1140,52 @@ fn detect_same_item_push<'tcx>(
walk_expr(&mut same_item_push_visitor, body);
if same_item_push_visitor.should_lint {
if let Some((vec, pushed_item)) = same_item_push_visitor.vec_push {
// Make sure that the push does not involve possibly mutating values
if let PatKind::Wild = pat.kind {
let vec_str = snippet_with_macro_callsite(cx, vec.span, "");
let item_str = snippet_with_macro_callsite(cx, pushed_item.span, "");
if let ExprKind::Path(ref qpath) = pushed_item.kind {
if_chain! {
if let Res::Local(hir_id) = qpath_res(cx, qpath, pushed_item.hir_id);
let node = cx.tcx.hir().get(hir_id);
if let Node::Binding(pat) = node;
if let PatKind::Binding(bind_ann, ..) = pat.kind;
if !matches!(bind_ann, BindingAnnotation::RefMut | BindingAnnotation::Mutable);
then {
span_lint_and_help(
cx,
SAME_ITEM_PUSH,
vec.span,
"it looks like the same item is being pushed into this Vec",
None,
&format!(
"try using vec![{};SIZE] or {}.resize(NEW_SIZE, {})",
item_str, vec_str, item_str
),
)
let vec_ty = cx.typeck_results().expr_ty(vec);
let ty = vec_ty.walk().nth(1).unwrap().expect_ty();
if cx
.tcx
.lang_items()
.clone_trait()
.map_or(false, |id| implements_trait(cx, ty, id, &[]))
{
// Make sure that the push does not involve possibly mutating values
if let PatKind::Wild = pat.kind {
let vec_str = snippet_with_macro_callsite(cx, vec.span, "");
let item_str = snippet_with_macro_callsite(cx, pushed_item.span, "");
if let ExprKind::Path(ref qpath) = pushed_item.kind {
if_chain! {
if let Res::Local(hir_id) = qpath_res(cx, qpath, pushed_item.hir_id);
let node = cx.tcx.hir().get(hir_id);
if let Node::Binding(pat) = node;
if let PatKind::Binding(bind_ann, ..) = pat.kind;
if !matches!(bind_ann, BindingAnnotation::RefMut | BindingAnnotation::Mutable);
then {
span_lint_and_help(
cx,
SAME_ITEM_PUSH,
vec.span,
"it looks like the same item is being pushed into this Vec",
None,
&format!(
"try using vec![{};SIZE] or {}.resize(NEW_SIZE, {})",
item_str, vec_str, item_str
),
)
}
}
} else if mutated_variables(pushed_item, cx).map_or(false, |mutvars| mutvars.is_empty()) {
span_lint_and_help(
cx,
SAME_ITEM_PUSH,
vec.span,
"it looks like the same item is being pushed into this Vec",
None,
&format!(
"try using vec![{};SIZE] or {}.resize(NEW_SIZE, {})",
item_str, vec_str, item_str
),
)
}
} else if mutated_variables(pushed_item, cx).map_or(false, |mutvars| mutvars.is_empty()) {
span_lint_and_help(
cx,
SAME_ITEM_PUSH,
vec.span,
"it looks like the same item is being pushed into this Vec",
None,
&format!(
"try using vec![{};SIZE] or {}.resize(NEW_SIZE, {})",
item_str, vec_str, item_str
),
)
}
}
}
Expand Down
17 changes: 17 additions & 0 deletions tests/ui/same_item_push.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -94,4 +94,21 @@ fn main() {
vec13.push(item);
item += 10;
}

// Fix #5979
let mut vec14: Vec<std::fs::File> = Vec::new();
for _ in 0..10 {
vec14.push(std::fs::File::open("foobar").unwrap());
}
// Fix #5979
#[derive(Clone)]
struct S {}

trait T {}
impl T for S {}

let mut vec15: Vec<Box<dyn T>> = Vec::new();
for _ in 0..10 {
vec15.push(Box::new(S {}));
}
}