Add #[track_caller] test.

Author: eddyb

tests/ui/lang/panic/track_caller.rs

@@ -0,0 +1,17 @@
+// Test that propagating `#[track_caller]` doesn't cause constant-related errors.
+
+// build-pass
+
+use spirv_std as _;
+
+#[track_caller]
+fn track_caller_maybe_panic(x: u32) {
+    if x > 0 {
+        panic!();
+    }
+}
+
+#[spirv(fragment)]
+pub fn main(x: u32) {
+    track_caller_maybe_panic(x);
+}