--skipProjCfg --skipParentCfg do not work when compiling koch from csources

[mratsim]

The most straightforward way of solving #8676 Usability: {.experimental: “ForLoopMacros”.} is required at all macro callsites is to use --experimental:ForLoopMacros when compiling concerned projects.

To avoid having to add that everytime we can use either of:

• nim.cfg
• nimble tasks

nim.cfg allows all compilations to take the experimental flag into account while nimble is restricted to predefined task.

Unfortunately during Travis and Appveyor CI, the nim.cfg of the project is contaminating the compilation of koch as root folder is a clone of the project.

Neither --skipProjCfg or --skipParentCfg prevent this contamination: https://travis-ci.org/status-im/nim-stint/jobs/418268022#L328-L329

$ git clone --depth 1 https://github.com/nim-lang/csources.git
Cloning into 'csources'...
remote: Counting objects: 933, done.
remote: Compressing objects: 100% (312/312), done.
remote: Total 933 (delta 793), reused 644 (delta 620), pack-reused 0
Receiving objects: 100% (933/933), 3.84 MiB | 5.31 MiB/s, done.
Resolving deltas: 100% (793/793), done.
Checking out files: 100% (4940/4940), done.
$ cd csources
$ sh build.sh
...
$ cd ..
$ export PATH=$PWD/bin:$PATH
$ nim c koch --skipProjCfg --skipParentCfg
Hint: used config file '/Users/travis/build/status-im/nim-stint/nim/config/nim.cfg' [Conf]
/Users/travis/build/status-im/nim-stint/nim.cfg(1, 3) Error: invalid argument for command line option: '--experimental'

[mratsim]

After rewriting the compilation script to:

  - cd ..
  - bin\nim --skipProjCfg --skipParentCfg c koch # Don't use stint's nim.cfg to compile koch
  - koch boot --skipProjCfg --skipParentCfg -d:release
  - koch --skipProjCfg --skipParentCfg nimble

I don't have the experimental issue however a new error crops up:

main.nim(13, 10) Error: nimcore MUST be defined for Nim's core tooling
FAILURE
The command "./koch boot --skipProjCfg --skipParentCfg -d:release" failed and exited with 1 during.

https://travis-ci.org/status-im/nim-stint/jobs/418298954#L457-L461

[Araq]

I'm not sure what you're messing around with, but put this into your nim.cfg:

@if nimHasForLoopMacros:
--experimental: forLoopMacros
@end

[mratsim]

I just tried the nim.cfg config, that doesn't work :/