Fix #2759: support params like @file.txt for dotc

[liufengyun]

Fix #2759: support params like @file.txt for dotc

The command line parser is migrated from Scalac for handling possible quotes in params.

A test case for this feature is here, it works on Linux/Mac/Windows: lampepfl/packtest#4

[olafurpg]

LGTM 👍 Thanks @liufengyun !

[liufengyun]

Hmm, the legacy CI is not happy:

[info] Test dotc.tests.dottyBooted started
possible data race involving globally reachable variable root in class Pattern: java.util.regex.Pattern.Node
  use -Ylog:checkReentrant+ to find out more about why the variable is reachable.
possible data race involving globally reachable variable matchRoot in class Pattern: java.util.regex.Pattern.Node
  use -Ylog:checkReentrant+ to find out more about why the variable is reachable.
possible data race involving globally reachable variable buffer in class Pattern: Array[Int]
  use -Ylog:checkReentrant+ to find out more about why the variable is reachable.
possible data race involving globally reachable variable namedGroups in class Pattern: java.util.Map[String, Integer]
  use -Ylog:checkReentrant+ to find out more about why the variable is reachable.
possible data race involving globally reachable variable groupNodes in class Pattern: Array[java.util.regex.Pattern.GroupHead]
  use -Ylog:checkReentrant+ to find out more about why the variable is reachable.
possible data race involving globally reachable variable capturingGroupCount in class Pattern: Int
  use -Ylog:checkReentrant+ to find out more about why the variable is reachable.
possible data race involving globally reachable variable localCount in class Pattern: Int
  use -Ylog:checkReentrant+ to find out more about why the variable is reachable.
7 warnings found
7 errors found
[error] Test dotc.tests.dottyBooted failed: java.lang.AssertionError: assertion failed: Wrong # of errors. Expected: 0, found: 7

@smarter @felixmulder @DarkDimius could you please advise?

[smarter]

This tells me two things:

• -Ycheck-reentrant is not passed to the compiler when compiling dotty in the new tests, that's an issue in the tests, that's bad! /cc @felixmulder
• -Ycheck-reentrant detects that there is a globally reachable value (Word) whose class (Regex) contains a field of type Pattern which has mutable fields. In general this might causes problem in multi-threaded code, but Pattern is documented as thread-safe (https://docs.oracle.com/javase/8/docs/api/java/util/regex/Pattern.html) so this should be fine. You can disable the check by adding the annotation @sharable in front of the declaration of Word.

[felixmulder]

It should indeed compile with check reentrant. Can it be enabled by this PR?

[smarter]

Opened #2769 to track this.

[liufengyun]

@felixmulder could you please check if this is the right place to put the check?