Rust: Add type inference regression tests for cfg!

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Copilot-Session: 2b6b35e8-4f05-4cf7-b229-2ddc3ebdd83c

Author: paldepind

rust/ql/test/library-tests/type-inference/cfg.rs

@@ -0,0 +1,17 @@
+pub fn expressions() {
+    let unix = cfg!(unix); // $ MISSING: certainType=unix:bool
+    let windows = cfg!(target_os = "windows"); // $ MISSING: certainType=windows:bool
+    let either = cfg!(any(unix, target_os = "windows")); // $ MISSING: certainType=either:bool
+    let always = cfg!(all()); // $ MISSING: certainType=always:bool
+    let never = cfg!(any()); // $ MISSING: certainType=never:bool
+}
+
+pub fn patterns() {
+    let value = Default::default(); // $ MISSING: target=default type=value:bool
+    match value {
+        cfg!(unix) => (),
+        cfg!(target_os = "windows") => (),
+        cfg!(any(unix, target_os = "windows")) => (),
+        _ => (),
+    }
+}

rust/ql/test/library-tests/type-inference/type-inference.expected

@@ -508,6 +508,11 @@ inferCertainType
 | blanket_impl.rs:299:44:299:44 | c |  | blanket_impl.rs:286:5:286:29 | MySqlConnection |
 | blanket_impl.rs:299:47:299:67 | "SELECT * FROM users" |  | {EXTERNAL LOCATION} | & |
 | blanket_impl.rs:299:47:299:67 | "SELECT * FROM users" | TRef | {EXTERNAL LOCATION} | str |
+| cfg.rs:1:22:7:1 | { ... } |  | {EXTERNAL LOCATION} | () |
+| cfg.rs:12:23:12:24 | TupleExpr |  | {EXTERNAL LOCATION} | () |
+| cfg.rs:13:40:13:41 | TupleExpr |  | {EXTERNAL LOCATION} | () |
+| cfg.rs:14:51:14:52 | TupleExpr |  | {EXTERNAL LOCATION} | () |
+| cfg.rs:15:14:15:15 | TupleExpr |  | {EXTERNAL LOCATION} | () |
 | closure.rs:4:19:39:5 | { ... } |  | {EXTERNAL LOCATION} | () |
 | closure.rs:6:13:6:22 | my_closure |  | {EXTERNAL LOCATION} | dyn Fn |
 | closure.rs:6:13:6:22 | my_closure | dyn(Args) | {EXTERNAL LOCATION} | (T_2) |
@@ -6003,6 +6008,13 @@ inferType
 | blanket_impl.rs:299:44:299:44 | c |  | blanket_impl.rs:286:5:286:29 | MySqlConnection |
 | blanket_impl.rs:299:47:299:67 | "SELECT * FROM users" |  | {EXTERNAL LOCATION} | & |
 | blanket_impl.rs:299:47:299:67 | "SELECT * FROM users" | TRef | {EXTERNAL LOCATION} | str |
+| cfg.rs:1:22:7:1 | { ... } |  | {EXTERNAL LOCATION} | () |
+| cfg.rs:9:19:17:1 | { ... } |  | {EXTERNAL LOCATION} | () |
+| cfg.rs:11:5:16:5 | match value { ... } |  | {EXTERNAL LOCATION} | () |
+| cfg.rs:12:23:12:24 | TupleExpr |  | {EXTERNAL LOCATION} | () |
+| cfg.rs:13:40:13:41 | TupleExpr |  | {EXTERNAL LOCATION} | () |
+| cfg.rs:14:51:14:52 | TupleExpr |  | {EXTERNAL LOCATION} | () |
+| cfg.rs:15:14:15:15 | TupleExpr |  | {EXTERNAL LOCATION} | () |
 | closure.rs:4:19:39:5 | { ... } |  | {EXTERNAL LOCATION} | () |
 | closure.rs:6:13:6:22 | my_closure |  | {EXTERNAL LOCATION} | dyn Fn |
 | closure.rs:6:13:6:22 | my_closure | dyn(Args) | {EXTERNAL LOCATION} | (T_2) |