Use of sublibrary problematic, due to GHC bug #25025

[mpilgrem]

vector-0.13.2.0 has introduced a sublibrary, and that is problematic because (a) GHC bug #25025 has not yet been fixed and (b) vector is a popular library. (The GHC bug is that GHC's -package <pkg> causes an installed package to be exposed that is not one listed by ghc-pkg list <pkg>.)

This has manifested at the Stack project, as it means that vector can no longer be used reliably in Haskell scripts:

• stack script can not access vector package commercialhaskell/stack#6704

[Shimuuar]

So in short stack script cannot work with public sublibraries. Only possible workaround is to split sublibrary into separate package. GHC will probably take quite some time sorting out things with -package. What are stack's plans in the meantime?

[mpilgrem]

@Shimuuar, I need to think it through but GHC also has a -package-id option that takes the id field of an installed package, rather than its name. So, perhaps, for the affected versions of GHC, Stack could:

• use stack script --package <pkg> to specify the name of the installed package (as now)
• use ghc-pkg field <pkg> id to get the id field's contents
• and then use -package-id with the id field's contents to expose the installed package

EDIT: That approach seems to work:

• Fix #6616 Use GHC's -package-id rather than -package commercialhaskell/stack#6710

Subject to a little testing, I may release a Stack 3.7.1 sooner rather than later.