> > I think to avoid this you will need to be careful to only apply these > flags when the BOOTSTRAP_TH flag is set. > In particular, I think what's happening is that we try to find the > GHC.KnownKey module and then start pulling in all of ghc-internal.
Ah yes. The command line does indeed invoke the *bootstrap *compiler, which of course does now know these flags. *But what business does the bootstrap compiler have with compiling GHC.Internal.Classes? * I would be entirely unsurprised if the bootstrap compiler stumbled on compiling a module that is so closely coupled to GHC's internals. Simon On Wed, 25 Mar 2026 at 13:02, Teo Camarasu <[email protected]> wrote: > Hi Simon, > > Note that this is occurring while compiling `ghc-boot-th-next`. This > package vendors the TemplateHaskell interfaces from ghc-internal and is > built by the boot compiler. You will find a bunch of CPP in the > TemplateHaskell modules like `GHC.Internal.TH.Syntax` that switches out > `ghc-internal` imports for `base` imports when bootstrapping so we can > compile with the boot compiler. For more context see `Note [Bootstrapping > Template Haskell]`. > > I think to avoid this you will need to be careful to only apply these > flags when the BOOTSTRAP_TH flag is set. > In particular, I think what's happening is that we try to find the > GHC.KnownKey module and then start pulling in all of ghc-internal. > > Cheers, > Teo > > On Wed, 25 Mar 2026, at 12:56 PM, Brandon Allbery via ghc-devs wrote: > > I'd suspect it's your boot compiler producing that error, and that what > changed might have been the file being compiled, causing a recompile with > the wrong compiler? > > On Wed, Mar 25, 2026 at 8:53 AM Simon Peyton Jones via ghc-devs < > [email protected]> wrote: > > Friends > > After 10 days of working on !15719 I have suddenly started getting > > /home/simonpj/code/HEAD-19/libraries/ghc-boot-th-next/../ghc-internal/src/GHC/Internal/Classes.hs:10:17: > error: [GHC-04924] > Unknown flag in {-# OPTIONS_GHC #-} pragma: -fdefines-known-key-names > | > 10 | {-# OPTIONS_GHC -fdefines-known-key-names #-} > | ^^^^^^^^^^^^^^^^^^^^^^^^^ > > I have no idea why this was fine until 10am this morning, and has suddenly > started happening now. > > *How does GHC decide what runtime flags it allows? * > `-fdefines-known-key-names` is in GHC.Driver.Session.fFlagsDeps. > > > I'm boggled that it worked until 10am and then abruptly stopped. > > Any advice? > > Simon > > _______________________________________________ > ghc-devs mailing list -- [email protected] > To unsubscribe send an email to [email protected] > > > > -- > brandon s allbery kf8nh > [email protected] > _______________________________________________ > ghc-devs mailing list -- [email protected] > To unsubscribe send an email to [email protected] > > >
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