#15646: ghci takes super long time to find the type of large fractional number -------------------------------------+------------------------------------- Reporter: Johannkokos | Owner: | JulianLeviston Type: bug | Status: new Priority: normal | Milestone: 8.6.1 Component: GHCi | Version: 8.4.3 Resolution: | Keywords: newcomer Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by JulianLeviston): I've been trying to build a profiled compiler. I adjusted `build.mk` by changing the `BuildFlavour` thusly: `BuildFlavour = prof` and commented out the `stage = 2`setting I had. I also added this to the bottom, to put profiling hooks across the typechecker: {{{ define add_mods_flag = $(foreach mod,$(2),$(eval $(basename $(mod))_HC_OPTS += $(1))) endef $(call add_mods_flag,-fprof-auto,$(wildcard compiler/typecheck/*.hs)) }}} I keep getting this error after `make clean && make -j4` in either the `ghc/compiler` or `ghc/` directories: {{{ GHC error in desugarer lookup in GHC.Real: Can't find interface-file declaration for type constructor or class mkRational Probable cause: bug in .hi-boot file, or inconsistent .hi file Use -ddump-if-trace to get an idea of which file caused the error ghc-stage1: panic! (the 'impossible' happened) (GHC version 8.7.20181012 for x86_64-apple-darwin): initDs Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} What should I do next? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15646#comment:49 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler