Not supported

The compiler validates syntax up front and rejects these with a located error and a hint, rather than miscompiling them:

• async def, await, async for, and async with
• match statements, type aliases, except*, and del of a name, an attribute, or a stepped slice
• from module import *
• *args, **kwargs, and keyword-only parameters on methods other than __init__, ** unpacking in a call, and positional-only parameters (/)
• Class keywords other than metaclass= (__init_subclass__ arguments)
• Decorators CPython does not define (@memoize, @timer, @debug, @pure, @type_check, @default_value, @wasm_export), which CPython rejects with NameError
• Module-level statements other than definitions. A WebAssembly module has no top-level run step, so only definitions run: X = 1, X: int = 1, X = helper(), X = ClassName(), def, class, and imports (a try/except ImportError guarded import included). Definitions that are not plain constants are evaluated once, in source order, when the module is instantiated; one that reads a definition appearing after it is refused, as it is a NameError in CPython. A module-level loop, if, try, bare call statement, augmented assignment, tuple unpacking, or write through a subscript or attribute is rejected, because it would otherwise be compiled away and later reads would see the value from before it. Put the code in a function and call it, or drive it from if __name__ == "__main__":, which is recognized as the entry point
• Third-party packages: the supported subset is your own modules plus the standard library above

If you find a program that compiles and answers differently from CPython, other than through integer width or a NaN in a collection, that is a bug: please report it.