Now that the same haskell-gi generates bindings automatically we need to be able to detect what version a user has when building Leksah. We are using Cabal flags in leksah.cabal:

flag gtk-318
    description:
        GTK+ is 3.18 or later

flag gtk-320
    description:
        GTK+ is 3.20 or later

Then later we have:

    if flag(gtk-318)
        pkgconfig-depends: gtk+-3.0 >= 3.18
        cpp-options:       -DMIN_VERSION_GTK_3_18

    if flag(gtk-320)
        pkgconfig-depends: gtk+-3.0 >= 3.20
        cpp-options:       -DMIN_VERSION_GTK_3_20

When using cabal-install the flags are disabled automatically when the pkgconfig-depends are not met.

It is not entirely satisfactory because:

• It does not work automatically with stack (this is the biggest drawback and why I am putting the issue here)
• You have to add a flag for every version check
• If the someone upgrades the underlying pkg-config library without rebuilding haskell-gi we will think they have newer bindings than they do.

Is there a way to make this work automatically with Stack? Alternatively can you suggest a better way to do this detection that will work automatically with Stack?