Auto merge of rust-lang#4495 - JohnTitor:fix-map-entry-false-positive, r=phansch

Fix `map_entry` false positive

Fixes rust-lang#4219

changelog: Fix `map_entry` false positive

Author: bors

clippy_lints/src/entry.rs

@@ -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::*;
@@ -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);
             then {
                 span_lint_and_then(self.cx, MAP_ENTRY, self.span,
                                    &format!("usage of `contains_key` followed by `insert` on a `{}`", self.ty), |db| {

tests/ui/entry.rs

@@ -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);
+    }
+}
+
 fn main() {}