fix: Incorrect closure capturing for let exprs

crates/hir-ty/src/infer/closure.rs

@@ -1229,10 +1229,11 @@ impl InferenceContext<'_> {
                     self.select_from_expr(*expr);
                 }
             }
-            Expr::Let { pat: _, expr } => {
+            Expr::Let { pat, expr } => {
                 self.walk_expr(*expr);
-                let place = self.place_of_expr(*expr);
-                self.ref_expr(*expr, place);
+                if let Some(place) = self.place_of_expr(*expr) {
+                    self.consume_with_pat(place, *pat);
+                }
             }
             Expr::UnaryOp { expr, op: _ }
             | Expr::Array(Array::Repeat { initializer: expr, repeat: _ })

crates/hir-ty/src/tests/closure_captures.rs

@@ -446,20 +446,44 @@ fn main() {
 }
 
 #[test]
-fn let_binding_is_a_ref_capture() {
+fn let_binding_is_a_ref_capture_in_ref_binding() {
     check_closure_captures(
         r#"
 //- minicore:copy
 struct S;
 fn main() {
     let mut s = S;
     let s_ref = &mut s;
+    let mut s2 = S;
+    let s_ref2 = &mut s2;
     let closure = || {
         if let ref cb = s_ref {
+        } else if let ref mut cb = s_ref2 {
         }
     };
 }
 "#,
-        expect!["83..135;49..54;112..117 ByRef(Shared) s_ref &'? &'? mut S"],
+        expect![[r#"
+            129..225;49..54;149..155 ByRef(Shared) s_ref &'? &'? mut S
+            129..225;93..99;188..198 ByRef(Mut { kind: Default }) s_ref2 &'? mut &'? mut S"#]],
+    );
+}
+
+#[test]
+fn let_binding_is_a_value_capture_in_binding() {
+    check_closure_captures(
+        r#"
+//- minicore:copy, option
+struct Box(i32);
+fn main() {
+    let b = Some(Box(0));
+    let closure = || {
+        if let Some(b) = b {
+            let _move = b;
+        }
+    };
+}
+"#,
+        expect!["73..149;37..38;103..104 ByValue b Option<Box>"],
     );
 }

crates/ide-diagnostics/src/handlers/moved_out_of_ref.rs

@@ -236,6 +236,24 @@ impl S {
         };
     }
 }
+"#,
+        )
+    }
+
+    #[test]
+    fn regression_20155() {
+        check_diagnostics(
+            r#"
+//- minicore: copy, option
+struct Box(i32);
+fn test() {
+    let b = Some(Box(0));
+    || {
+        if let Some(b) = b {
+            let _move = b;
+        }
+    };
+}
 "#,
         )
     }