stack install.hs hie-8.4.4 installs ghc-8.6.2 and ghc-8.6.4 compilers as well

[nponeccop]

And 3 respective snapshots: lts-12.26, lts-13.12, nightly-2018-12-15.

I think that at least one of the 2 "extra" snapshots/ghcs can be eliminated.

[jneira]

As a side note, stack script does not use .stack/config.yaml so it reinstalls ghc-8.6.2 in the default local-programs-path if you have change it to other location in the config.
Hopefully it seems it is going to honour it: commercialhaskell/stack#3887 (comment)

[nponeccop]

@jneira apparently the stack bug is already closed. Can you recheck with stack-git?

[jneira]

Of course, i've just downloaded the artifacts of build here: https://dev.azure.com/commercialhaskell/stack/_build/results?buildId=1170
and it honours my user config file. 👍

[fendor]

Yes, normally only one additional snapshot should be required.
The PR #1168 may address this problem.

[samuelpilz]

This is fixed in #1168

[nponeccop]

It isn't merged as of April 20

[fendor]

Should be fixed now, please check!

[lukel97]

On a related note, is it possible to use
system-ghc: true in shake.yaml to avoid stack having to download another snapshot/compiler? Assuming that install.hs is backwards compatible with other versions of ghc?

[fendor]

Possibly yes. @power-fungus?

[samuelpilz]

I will test that. What happens if there is no system-ghc?

[fendor]

Afaik, it errros out.

[nponeccop]

Should be fixed now, please check!

works for me