moved renamed docs formatted | last-use-in-cap-clause.rs

Author: Kivooeo

tests/ui/closures/closure-upvar-last-use-analysis.rs

@@ -0,0 +1,32 @@
+//! Regression test for issue #1399
+//!
+//! This test ensures that the compiler's last-use analysis correctly handles variables
+//! that are captured by closures (upvars). The original issue was that the analyzer
+//! would incorrectly optimize variable usage as "last use" and perform moves, even when
+//! the variable was later needed by a closure that captured it.
+//!
+//! See: https://github.com/rust-lang/rust/issues/1399
+
+//@ run-pass
+
+struct A {
+    _a: Box<isize>
+}
+
+fn foo() -> Box<dyn FnMut() -> isize + 'static> {
+    let k: Box<_> = Box::new(22);
+    
+    // This use of k.clone() should not be treated as a "last use" 
+    // even though the closure below doesn't actually capture k
+    let _u = A { _a: k.clone() };
+    
+    // The closure doesn't actually use k, but the analyzer needs to handle
+    // the potential capture scenario correctly
+    let result = || 22;
+    
+    Box::new(result)
+}
+
+pub fn main() {
+    assert_eq!(foo()(), 22);
+}