Add test for issue-76375

Author: JohnTitor

src/test/ui/mir/auxiliary/issue_76375_aux.rs

@@ -0,0 +1,14 @@
+// edition:2018
+// compile-flags: -Z mir-opt-level=2 -Z unsound-mir-opts
+
+#[inline(always)]
+pub fn f(s: bool) -> String {
+    let a = "Hello world!".to_string();
+    let b = a;
+    let c = b;
+    if s {
+        c
+    } else {
+        String::new()
+    }
+}

src/test/ui/mir/issue-76375.rs

@@ -0,0 +1,15 @@
+// edition:2018
+// build-pass
+// compile-flags: -Z mir-opt-level=2 -L.
+// aux-build:issue_76375_aux.rs
+
+#![crate_type = "lib"]
+
+extern crate issue_76375_aux;
+
+pub async fn g() {
+    issue_76375_aux::f(true);
+    h().await;
+}
+
+pub async fn h() {}