commit 8f62f9b87aacb787e505308f373a8fa444e6fe8a
author Scott Todd <scotttodd@google.com> Thu Aug 24 13:31:53 2023 -0700
committer GitHub <noreply@github.com> Thu Aug 24 20:31:53 2023 +0000
tree 00841c5d0106c9a17d71021096b99c88ca446882
parent 308637a1b8b48c9004787828a7776f6ad5c62587

Fix ir_tool argparse subcommand usage. (#14804)

The "cp" alias for "copy" was not working, instead producing an error:
`error: Unrecognized sub-command {args.sub_command}"`.

The docs (https://docs.python.org/3/library/argparse.html#sub-commands)
recommend using

```python
parser = argparse.ArgumentParser()
subparsers = parser.add_subparsers(required=True)

parser_foo = subparsers.add_parser('foo')
parser_foo.set_defaults(func=foo)

# parse the args and call whatever function was selected
args = parser.parse_args(...)
args.func(args)
```

After switching to that style, "cp" and "copy" both work.

If an unknown subcommand is used, argparse has its own error message:
```bash
$ python -m iree.compiler.tools.ir_tool foo
usage: __main__.py [-h] {copy,cp,strip-data} ...
__main__.py: error: argument sub_command: invalid choice: 'foo' (choose from 'copy', 'cp', 'strip-data')
```
(and the program returns exit code `2`, not `0`)