cxx-qt: export static assertions for cxx-qt-gen

This allows for CxxQtSignalHandler to have it's size and align
checked by cxx-qt-gen.

crates/cxx-qt/Cargo.toml

@@ -20,6 +20,7 @@ categories = ["api-bindings", "gui"]
 [dependencies]
 cxx.workspace = true
 cxx-qt-macro.workspace = true
+static_assertions = "1.1.0"
 
 [dev-dependencies]
 cxx.workspace = true

crates/cxx-qt/src/lib.rs

@@ -18,6 +18,11 @@ pub use cxx_qt_macro::qobject;
 pub use cxxqtsignalhandler::{CxxQtSignalHandler, CxxQtSignalHandlerClosure};
 pub use cxxqtthread::CxxQtThread;
 
+// Export static assertions that can then be used in cxx-qt-gen generation
+//
+// These are currently used to ensure that CxxQtSignalHandler has the right size
+pub use static_assertions::{assert_eq_align, assert_eq_size};
+
 /// This trait is automatically implemented for all types which are marked as `#[qobject]`.
 /// It provides information about the type that is wrapped by the QObject, as well as the methods
 /// that Cxx-Qt will generate for the QObject.