Fix mill script for parameter starting with -i

[romain-gilles-ultra]

Context

There is an issue in the build pipeline the following job is falling:

./mill --import ivy:io.chris-kipp::mill-github-dependency-graph::0.2.5 showNamed io.kipp.mill.github.dependency.graph.Graph/generate
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed

  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0
  0     0    0     0    0     0      0      0 --:--:--  0:00:01 --:--:--     0
  0 5[7](https://github.com/com-lihaoyi/mill/actions/runs/8752465078/job/24020171634#step:5:8).3M    0 19288    0     0   9993      0  1:40:23  0:00:01  1:40:22  9993
 94 57.3M   94 54.1M    0     0  22.1M      0  0:00:02  0:00:02 --:--:-- 22.1M
[10](https://github.com/com-lihaoyi/mill/actions/runs/8752465078/job/24020171634#step:5:11)0 57.3M  100 57.3M    0     0  23.3M      0  0:00:02  0:00:02 --:--:-- 23.3M
Preparing Java 17.0.10 runtime; this may take a minute or two ...
[info] compiling 3 Scala sources to /home/runner/work/mill/mill/out/mill-build/compile.dest/classes ...
[info] done compiling
Parsing exception Position 1:[14](https://github.com/com-lihaoyi/mill/actions/runs/8752465078/job/24020171634#step:5:15), found "=./mill"
Error: Process completed with exit code 1.

The issue is coming from the ./mill sh script here:

 # first arg is a long flag for "--interactive" or starts with "-i"
if [ "$1" = "--bsp" ] || [ "${1%"-i"*}" != "$1" ] || [ "$1" = "--interactive" ] || [ "$1" = "--no-server" ] || [ "$1" = "--repl" ] || [ "$1" = "--help" ] ; then
  # Need to preserve the first position of those listed options
  MILL_FIRST_ARG=$1
  shift
fi

If you pass -i or --import it will match the if statement and more precisely the [ "${1%"-i"*}" != "$1" ] part of the if statement.

Solution

Looking at the POSIX documentation of the: POSIX shell variables and parameter substitution

${parameter%pattern}
${parameter%%pattern}

If the POSIX shell pattern matches the end of the value of parameter, then the value of this substitution is the value
of parameter with the matched portion deleted; otherwise, the value of parameter is substituted. In the first form,
the smallest matching pattern is deleted; in the second form, the largest matching pattern is deleted.

It sounds like % matches and substitutes the end of the parameter which explains the issue.
While the following approach uses the beginning of the parameter:

${parameter#pattern}
${parameter##pattern}

If the POSIX shell pattern matches the beginning of the value of parameter, then the value of this substitution is the
value of parameter with the matched portion deleted; otherwise, the value of parameter is substituted. In the first
form, the smallest matching pattern is deleted; in the second form, the largest matching pattern is deleted.

So by replacing [ "${1%"-i"*}" != "$1" ] by [ "${1#"-i"}" != "$1" ] it should solve it 🤞

[lihaoyi]

Can you write a proper PR description explaining what you believe the problem is and why this is the correct solution?

[romain-gilles-ultra]

Hi @lihaoyi
Sorry for this PR hope it's better now 🤗

[lihaoyi]

@romain-gilles-ultra thanks! Can you verify that passing in flags like ./mill -i -j 4 __.compile and ./mill -ij4 __.compile continues to work

[romain-gilles-ultra]

Hi @lihaoyi
Sorry for the delay but yes it works ;)

[lefou]

Thank you!