PS: Note [Bootstrapping Template Haskell] does not mention BOOTSTRAP_TH!
On Wed, 25 Mar 2026 at 13:08, Simon Peyton Jones < [email protected]> wrote: > 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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