Auto merge of #15625 - jDomantas:domantas/fix-15623, r=HKalbasi

fix: Don't skip closure captures after let-else

As I understand that `return` was left there by accident. It caused capture analysis to skip the rest of the block after a let-else, and then missed captures caused incorrect results in borrowck, closure hints, layout calculation, etc.

Fixes #15623

I didn't understand why I using the example from #15623 as-is doesn't work - I don't get the warnings unless I remove the `call_me()` call, even on the same commit as my own RA version which does show those warnings.

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

@@ -469,13 +469,13 @@ impl InferenceContext<'_> {
                         Statement::Let { pat, type_ref: _, initializer, else_branch } => {
                             if let Some(else_branch) = else_branch {
                                 self.consume_expr(*else_branch);
-                                if let Some(initializer) = initializer {
-                                    self.consume_expr(*initializer);
-                                }
-                                return;
                             }
                             if let Some(initializer) = initializer {
-                                self.walk_expr(*initializer);
+                                if else_branch.is_some() {
+                                    self.consume_expr(*initializer);
+                                } else {
+                                    self.walk_expr(*initializer);
+                                }
                                 if let Some(place) = self.place_of_expr(*initializer) {
                                     self.consume_with_pat(place, *pat);
                                 }

crates/hir-ty/src/layout/tests/closure.rs

@@ -255,3 +255,17 @@ fn ellipsis_pattern() {
         }
     }
 }
+
+#[test]
+fn regression_15623() {
+    size_and_align_expr! {
+        let a = 2;
+        let b = 3;
+        let c = 5;
+        move || {
+            let 0 = a else { return b; };
+            let y = c;
+            y
+        }
+    }
+}

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

@@ -1170,6 +1170,29 @@ fn f() {
     loop {}
     for _ in 0..2 {}
 }
+"#,
+        );
+    }
+
+    #[test]
+    fn regression_15623() {
+        check_diagnostics(
+            r#"
+//- minicore: fn
+
+struct Foo;
+
+impl Foo {
+    fn needs_mut(&mut self) {}
+}
+
+fn foo(mut foo: Foo) {
+    let mut call_me = || {
+        let 0 = 1 else { return };
+        foo.needs_mut();
+    };
+    call_me();
+}
 "#,
         );
     }