commit 52f62b8afdd9663b37f8dd94a247eaa654857bc7
author Scott Todd <scotttodd@google.com> Tue May 10 17:51:34 2022 -0700
committer GitHub <noreply@github.com> Tue May 10 17:51:34 2022 -0700
tree 12698298ddc2f828b788bf4754142b54224baaff
parent 3209c6b33e87ef5357dd806e63b870d87ddc42ce

Consistently use two dashes for long command line options. (#9064)

This updates our usage of command line flags we control (MLIR flags and IREE flags) to use two dashes for long options. Short options (e.g. `-o module.vmfb`) and options for tools outside our control (e.g. `-fsanitize=address`) remain unchanged.

This is part of addressing a source of confusion explained in https://github.com/google/iree/issues/5931. Several of our tools have bad failure modes when receiving malformed flags (typos, extra spaces, overlooking implicit stdin, etc.). We can reduce the risk of user errors by being consistent across the project in how we use command line flags.

---

⚠ Bikeshedding ahead ⚠

### Rationale

In general (across tools, languages, and platforms), command line tools use a mix of _positional_ arguments and _keyword_ arguments. Positional arguments use no prefix like `-` or `--` and are parsed in the order they appear. Keyword arguments use some prefix (typically `-` or `--`) followed by the flag name then a separator (typically `=` or ` `) and then the value.

Within keyword arguments, there are also "short" and "long" options. Short options are usually one letter versions of long options, and sometimes multiple short options can be mixed together. For example, see https://man7.org/linux/man-pages/man1/tar.1.html and equivalent commands like
* `tar --create --verbose --file etc.tar /etc`
* `tar -c -v -f etc.tar /etc`
* `tar -cvf etc.tar /etc`

Not all tools follow that convention, and parsing can be made to be more forgiving, but internal consistency within a project is worth aiming for.

Other discussions:

* [What's the difference betwen the single dash and double dash flags on shell commands?](https://serverfault.com/questions/387935/whats-the-difference-betwen-the-single-dash-and-double-dash-flags-on-shell-comm)
* [What's the difference between one-dash and two-dashes for command prompt parameters?](https://superuser.com/questions/372203/whats-the-difference-between-one-dash-and-two-dashes-for-command-prompt-paramet)

---

This change was generated via a mix of regex find/replaces and manual review. See each commit for more details.