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Pants

<@U066LC126>: just catching up with the 'mutable' jars discussion. Yes we use them. Yes they are difficult to use, I don't think its working as intended.  Basically you have to bump the rev each time you want to refresh the jar which I think is one of the main things 'mutable' is supposed to help you avoid.

It was really confusing for me for the first time, spent some time to figure it out.

I have had an issue open for a while: <https://github.com/pantsbuild/pants/issues/951>

if you're bumping the rev then what is 'mutable' doing?

<@U053H6LQS>: yeah, I found that confusing when I ran into it. It has no tests, so I’m not surprised that it is difficult to use

Why do we have a fail-slow flag for pytest, when we also have a fail-fast flag?

Any non-twitter peeps have a couple minutes to take a look at: <https://rbcommons.com/s/twitter/r/3490/>

`src/python/pants/backend/jvm/subsystems/scala_platform.py`

I'm confused about how the `--runtime-spec` option is supposed to work when using 2.11

oh you mean when using 2.11 as the version...

to use the custom runtime spec you need to use ‘custom’ as the version currently

```  def compiler_classpath(self, products):
    """Return the proper classpath based on products and scala version."""
    compiler_name = scala_build_info.get(self._get_label()).compiler_name
    return self.tool_classpath_from_products(products, compiler_name, scope=self.options_scope)```

```  'custom': major_version_info(
    full_version='2.10.4',
    compiler_name='scalac',
    runtime_name='runtime_default',
    repl_name='scala-repl',
    style_name='scalastyle',
    style_version='0.3.2'),```

AFAICT if you use custom, you're stuck with 2.10.4 for scalac, which is broken

I see no way to override the major version info struct there

no you are just currently stuck with specifying your target as scalac in the root

the whole bootstrap thing is pretty confusing

Well, I don't see how the code reflects that logic though

should be much better after the engine refactor

```    def register_scala_compiler(version):
      name = scala_build_info[version].compiler_name
      version = scala_build_info[version].full_version
      _register_tool('org.scala-lang', 'scala-compiler', name, version)```

So the version will be misnamed, but it'll still look at `//:scalac`