Auto merge of #101410 - dingxiangfei2009:fix-let-else-scoping, r=jackh726

Reorder nesting scopes and declare bindings without drop schedule

Fix #99228
Fix #99975

Storages are previously not declared before entering the `else` block of a `let .. else` statement. However, when breaking out of the pattern matching into the `else` block, those storages are recorded as scheduled for drops. This is not expected.

This MR fixes this issue by not scheduling the drops for those storages.

cc `@est31`

3 files changed, 22 insertions, 1 deletions

diff --git a/src/test/ui/async-await/async-await-let-else.no-drop-tracking.stderr b/src/test/ui/async-await/async-await-let-else.no-drop-tracking.stderr
index 435cc845870..7f93563e288 100644
--- a/src/test/ui/async-await/async-await-let-else.no-drop-tracking.stderr
+++ b/src/test/ui/async-await/async-await-let-else.no-drop-tracking.stderr
@@ -35,7 +35,7 @@ LL |         bar2(Rc::new(())).await
    |              |
    |              has type `Rc<()>` which is not `Send`
 LL |     };
-   |      - `Rc::new(())` is later dropped here
+   |     - `Rc::new(())` is later dropped here
 note: required by a bound in `is_send`
   --> $DIR/async-await-let-else.rs:19:15
    |
diff --git a/src/test/ui/let-else/issue-99975.rs b/src/test/ui/let-else/issue-99975.rs
new file mode 100644
index 00000000000..80f63556194
--- /dev/null
+++ b/src/test/ui/let-else/issue-99975.rs
@@ -0,0 +1,20 @@
+// run-pass
+// compile-flags: -C opt-level=3 -Zvalidate-mir
+
+#![feature(let_else)]
+
+fn return_result() -> Option<String> {
+    Some("ok".to_string())
+}
+
+fn start() -> String {
+    let Some(content) = return_result() else {
+        return "none".to_string()
+    };
+
+    content
+}
+
+fn main() {
+    start();
+}
diff --git a/src/test/ui/let-else/let-else-temporary-lifetime.rs b/src/test/ui/let-else/let-else-temporary-lifetime.rs
index 07fcc16e7bb..8542c3496b0 100644
--- a/src/test/ui/let-else/let-else-temporary-lifetime.rs
+++ b/src/test/ui/let-else/let-else-temporary-lifetime.rs
@@ -1,4 +1,5 @@
 // run-pass
+// compile-flags: -Zvalidate-mir
 #![feature(let_else)]
 
 use std::fmt::Display;