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Auto merge of #5908 - giraffate:fix_fp_for_same_item_push, r=flip1995

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Fix FP for `same_item_push`

Fixes https://github.com/rust-lang/rust-clippy/issues/5902

changelog: Fix FP for `same_item_push` where the pushed variable is mutated.
This commit is contained in:
bors 2020-08-17 16:49:03 +00:00
parent 838c201af9 99ba290a14
commit 9360ca6dc2
2 changed files with 33 additions and 5 deletions
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30
clippy_lints/src/loops.rs
View file

@ -1141,11 +1141,31 @@ fn detect_same_item_push<'tcx>(
if same_item_push_visitor.should_lint { if same_item_push_visitor.should_lint {
if let Some((vec, pushed_item)) = same_item_push_visitor.vec_push { if let Some((vec, pushed_item)) = same_item_push_visitor.vec_push {
// Make sure that the push does not involve possibly mutating values // Make sure that the push does not involve possibly mutating values
if mutated_variables(pushed_item, cx).map_or(false, |mutvars| mutvars.is_empty()) { if let PatKind::Wild = pat.kind {
if let PatKind::Wild = pat.kind { let vec_str = snippet_with_macro_callsite(cx, vec.span, "");
let vec_str = snippet_with_macro_callsite(cx, vec.span, ""); let item_str = snippet_with_macro_callsite(cx, pushed_item.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( span_lint_and_help(
cx, cx,
SAME_ITEM_PUSH, SAME_ITEM_PUSH,

8
tests/ui/same_item_push.rs
View file

@ -86,4 +86,12 @@ fn main() {
for a in vec_a { for a in vec_a {
vec12.push(2u8.pow(a.kind)); vec12.push(2u8.pow(a.kind));
} }
// Fix #5902
let mut vec13: Vec<u8> = Vec::new();
let mut item = 0;
for _ in 0..10 {
vec13.push(item);
item += 10;
}
} }