Test trying to cfg-remove an if expression

src/test/ui/parser/if-attrs/bad-cfg.rs

@@ -0,0 +1,5 @@
+#![feature(stmt_expr_attributes)]
+
+fn main() {
+    let _ = #[cfg(FALSE)] if true {}; //~ ERROR removing an expression
+}

src/test/ui/parser/if-attrs/bad-cfg.stderr

@@ -0,0 +1,8 @@
+error: removing an expression is not supported in this position
+  --> $DIR/bad-cfg.rs:4:13
+   |
+LL |     let _ = #[cfg(FALSE)] if true {};
+   |             ^^^^^^^^^^^^^
+
+error: aborting due to previous error
+