Re: 8.2.1 changes to iface/FlagChecker.hs

Thanks, I added my two cents to the ticket. On Thu, Aug 3, 2017 at 12:37 PM, George Colpitts wrote:

I reported this in https://ghc.haskell.org/trac/ghc/ticket/13604

On Thu, Aug 3, 2017 at 4:32 PM Evan Laforge wrote:

...

My program uses the GHC API to provide a REPL, and upgrading to 8.2.1 broke that... well, just made it really slow. Where it used to quickly load the compiled files, it now wants to recompile everything as bytecode which makes 1s startup time go to 1m. The reason was it now thinks flags have changed. I tracked it down to changes in FlagChecker.hs, documented with https://ghc.haskell.org/trac/ghc/ticket/11798 and https://ghc.haskell.org/trac/ghc/ticket/10923, which add -fhpc and -O to the tracked flags. -fhpc means loading tests in ghci can never work, because ghci rejects the -fhpc flag, and likewise -O means ghci can never load optimized files for the same reason.

It seems like the easiest solution might be to just have ghci not reject -fhpc and -O. Of course we could also revert those changes, but they're justified in the trac tickets.

Of course this means I'm loading optimized code together with bytecode compiled code and maybe that's a bad thing (or for tests, -fhpc with non-hpc). But I've been doing this for something like 7 years and it's been fine.

Unrelatedly, I was hoping compiles would get faster, but they seem a bit slower, from around 3m20s to around 4m :( I can track down per-file timing changes if it would be interesting to someone.

Also thanks to whoever put trac tickets in the comments, it makes it really easy to find out why a change was made. _______________________________________________ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/glasgow-haskell-users