Rollup merge of rust-lang#157475 - veluca93:optimize-smoke, r=jieyouxu

Add a smoke test for the optimize attribute.

Tracking issue: rust-lang#54882
Stabilization PR: rust-lang#157273

Author: jhpratt

tests/ui/attributes/optimize-smoke-test.rs

@@ -0,0 +1,25 @@
+//! Basic smoke test for `#[optimize(..)]` attributes.
+//@ run-pass
+
+#![feature(optimize_attribute)]
+
+#[optimize(speed)]
+fn optimized_speed() -> i32 {
+    42
+}
+
+#[optimize(size)]
+fn optimized_size() -> i32 {
+    42
+}
+
+#[optimize(none)]
+fn optimized_none() -> i32 {
+    42
+}
+
+fn main() {
+    assert_eq!(optimized_speed(), 42);
+    assert_eq!(optimized_size(), 42);
+    assert_eq!(optimized_none(), 42);
+}