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Fix map_entry false positive #4495

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merged 2 commits into from
Sep 4, 2019
Merged

Fix map_entry false positive #4495

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c94c5e9
Fix `map_entry` false positive
JohnTitor Sep 3, 2019
5c760f0
Improve tests
JohnTitor Sep 4, 2019
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3 changes: 2 additions & 1 deletion clippy_lints/src/entry.rs
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
use crate::utils::SpanlessEq;
use crate::utils::{get_item_name, higher, match_type, paths, snippet, span_lint_and_then, walk_ptrs_ty};
use crate::utils::{get_item_name, higher, match_type, paths, snippet, snippet_opt, span_lint_and_then, walk_ptrs_ty};
use if_chain::if_chain;
use rustc::hir::intravisit::{walk_expr, NestedVisitorMap, Visitor};
use rustc::hir::*;
Expand Down Expand Up @@ -140,6 +140,7 @@ impl<'a, 'tcx, 'b> Visitor<'tcx> for InsertVisitor<'a, 'tcx, 'b> {
if path.ident.name == sym!(insert);
if get_item_name(self.cx, self.map) == get_item_name(self.cx, &params[0]);
if SpanlessEq::new(self.cx).eq_expr(self.key, &params[1]);
if snippet_opt(self.cx, self.map.span) == snippet_opt(self.cx, params[0].span);
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Hmm, in general I don't think comparing the span's text is very robust, but I think in this case it should be fine 👍

then {
span_lint_and_then(self.cx, MAP_ENTRY, self.span,
&format!("usage of `contains_key` followed by `insert` on a `{}`", self.ty), |db| {
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14 changes: 14 additions & 0 deletions tests/ui/entry.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -68,4 +68,18 @@ fn insert_other_if_absent<K: Eq + Hash, V>(m: &mut HashMap<K, V>, k: K, o: K, v:
}
}

// should not trigger, because the one uses different HashMap from another one
fn insert_from_different_map<K: Eq + Hash, V>(m: HashMap<K, V>, n: &mut HashMap<K, V>, k: K, v: V) {
if !m.contains_key(&k) {
n.insert(k, v);
}
}

// should not trigger, because the one uses different HashMap from another one
fn insert_from_different_map2<K: Eq + Hash, V>(m: &mut HashMap<K, V>, n: &mut HashMap<K, V>, k: K, v: V) {
if !m.contains_key(&k) {
n.insert(k, v);
}
}

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Could you also add the following test as described in the issue (where one is mut and the other is not):

fn insert_other<K: Eq + Hash, V>(m: HashMap<K, V>, n: &mut HashMap<K, V>, k: K, v: V) {
    if !m.contains_key(&k) {
        n.insert(k, v);
    }
}

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added the test (and renamed)

fn main() {}