[python] Print the diagnostic in emitWarning (warnings were silently dropped)

[udsy19]

Summary

cudaq.kernel.utils.emitWarning never shows the warning. It formats the diagnostic into a local msg and then the function ends without printing it, so the only visible effect is a stray bold escape with no text. It also labels the diagnostic error: even though it is a warning.

Root cause

def emitWarning(msg):
    print(Color.BOLD, end='')
    try:
        raise RuntimeError(msg)
    except RuntimeError:
        with set_tracebacklimit(None):
            offendingSrc = traceback.format_stack()
        if len(offendingSrc):
            msg = (Color.YELLOW + "error: " + ... + msg + ...)   # reassigned, never printed

The sibling PyASTBridge.emitWarning in ast_bridge.py ends with print(msg) and uses a warning: label. This copy dropped the print. The real caller is the non-slots=True dataclass advisory in utils.py (mlirTypeFromPyType), which users never actually saw.

Fix

Print the formatted message, and label it warning: to match the sibling and the function's purpose.

Tests

Added python/tests/kernel/test_emit_warning.py (capsys): asserts the warning body reaches the user and that the label is warning:, not error:.

[copy-pr-bot]

This pull request requires additional validation before any workflows can run on NVIDIA's runners.

Pull request vetters can view their responsibilities here.

Contributors can view more details about this message here.