add miri test via const fn

src/test/mir-opt/issue-101867.rs

@@ -1,4 +1,4 @@
-#![feature(let_else)]
+#![cfg_attr(bootstrap, feature(let_else))]
 
 // EMIT_MIR issue_101867.main.mir_map.0.mir
 fn main() {

src/test/ui/let-else/const-fn.rs

@@ -0,0 +1,19 @@
+// run-pass
+// issue #101932
+
+#![cfg_attr(bootstrap, feature(let_else))]
+
+const fn foo(a: Option<i32>) -> i32 {
+    let Some(a) = a else {
+        return 42
+    };
+
+    a + 1
+}
+
+fn main() {
+    const A: i32 = foo(None);
+    const B: i32 = foo(Some(1));
+
+    println!("{} {}", A, B);
+}