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  • Rodrigo Mesquita's avatar
    Hardwire a better unit-id for ghc · 3fdb18f8
    Rodrigo Mesquita authored and Marge Bot's avatar Marge Bot committed
    Previously, the unit-id of ghc-the-library was fixed as `ghc`.
    This was done primarily because the compiler must know the unit-id of
    some packages (including ghc) a-priori to define wired-in names.
    However, as seen in #20742, a reinstallable `ghc` whose unit-id is fixed
    to `ghc` might result in subtle bugs when different ghc's interact.
    A good example of this is having GHC_A load a plugin compiled by GHC_B,
    where GHC_A and GHC_B are linked to ghc-libraries that are ABI
    incompatible. Without a distinction between the unit-id of the ghc library
    GHC_A is linked against and the ghc library the plugin it is loading was
    compiled against, we can't check compatibility.
    This patch gives a slightly better unit-id to ghc (ghc-version) by
    (1) Not setting -this-unit-id to ghc, but rather to the new unit-id (modulo stage0)
    (2) Adding a definition to `GHC.Settings.Config` whose value is the new unit-id.
        (2.1) `GHC.Settings.Config` is generated by Hadrian
        (2.2) and also by cab...