fix: map_entry FP on struct member

Author: profetia

clippy_lints/src/entry.rs

@@ -8,7 +8,7 @@ use core::fmt::{self, Write};
 use rustc_errors::Applicability;
 use rustc_hir::hir_id::HirIdSet;
 use rustc_hir::intravisit::{Visitor, walk_expr};
-use rustc_hir::{Block, Expr, ExprKind, HirId, Pat, Stmt, StmtKind, UnOp};
+use rustc_hir::{Block, Expr, ExprKind, HirId, Pat, QPath, Stmt, StmtKind, UnOp};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::declare_lint_pass;
 use rustc_span::{DUMMY_SP, Span, SyntaxContext, sym};
@@ -500,7 +500,7 @@ impl<'tcx> Visitor<'tcx> for InsertSearcher<'_, 'tcx> {
                 self.visit_non_tail_expr(insert_expr.value);
                 self.is_single_insert = is_single_insert;
             },
-            _ if SpanlessEq::new(self.cx).eq_expr(self.map, expr) => {
+            _ if is_map_used(self.cx, self.map, expr) => {
                 self.is_map_used = true;
             },
             _ => match expr.kind {
@@ -562,6 +562,22 @@ impl<'tcx> Visitor<'tcx> for InsertSearcher<'_, 'tcx> {
     }
 }
 
+fn is_map_used(cx: &LateContext<'_>, map: &Expr<'_>, expr: &Expr<'_>) -> bool {
+    if SpanlessEq::new(cx).eq_expr(map, expr) {
+        return true;
+    }
+
+    match map.kind {
+        ExprKind::Field(inner, _) | ExprKind::Index(inner, _, _) => is_map_used(cx, inner, expr),
+        ExprKind::Path(QPath::Resolved(_, map_path))
+            if let ExprKind::Path(QPath::Resolved(_, expr_path)) = expr.kind =>
+        {
+            SpanlessEq::new(cx).eq_path(map_path, expr_path)
+        },
+        _ => false,
+    }
+}
+
 struct InsertSearchResults<'tcx> {
     edits: Vec<Edit<'tcx>>,
     allow_insert_closure: bool,

tests/ui/entry.fixed

@@ -186,4 +186,27 @@ fn issue12489(map: &mut HashMap<u64, u64>) -> Option<()> {
     Some(())
 }
 
+mod issue13934 {
+    use std::collections::HashMap;
+
+    struct Member {}
+
+    pub struct Foo {
+        members: HashMap<u8, Member>,
+    }
+
+    impl Foo {
+        pub fn should_also_not_cause_lint(&mut self, input: u8) {
+            if self.members.contains_key(&input) {
+                todo!();
+            } else {
+                self.other();
+                self.members.insert(input, Member {});
+            }
+        }
+
+        fn other(&self) {}
+    }
+}
+
 fn main() {}

tests/ui/entry.rs

@@ -190,4 +190,27 @@ fn issue12489(map: &mut HashMap<u64, u64>) -> Option<()> {
     Some(())
 }
 
+mod issue13934 {
+    use std::collections::HashMap;
+
+    struct Member {}
+
+    pub struct Foo {
+        members: HashMap<u8, Member>,
+    }
+
+    impl Foo {
+        pub fn should_also_not_cause_lint(&mut self, input: u8) {
+            if self.members.contains_key(&input) {
+                todo!();
+            } else {
+                self.other();
+                self.members.insert(input, Member {});
+            }
+        }
+
+        fn other(&self) {}
+    }
+}
+
 fn main() {}