Simon Peyton Jones via ghc-devs wrote:
You'll have seen a brief flurry of commits from me, of which this is the biggest. I've managed to spend some time on the typechecker recently, and this is the result.
I'm pleased with the results (simpler code, more predictable behaviour), but although I worked through the changes with Richard, I may have introduced new bugs, so keep an eye out.
Simon, I suspect these commits may be responsible for 11 test failures: Unexpected results from: TEST="T9857 T12007 T9732 T9783 T9867 unboxed-wrapper-naked match-unboxed num T12698 T4439 unboxed-wrapper" SUMMARY for test run started at Sun Oct 23 16:56:26 2016 AEDT 0:00:02 spent to go through 11 total tests, which gave rise to 47 test cases, of which 36 were skipped 0 had missing libraries 0 expected passes 0 expected failures 0 caused framework failures 0 unexpected passes 11 unexpected failures 0 unexpected stat failures Unexpected failures: deSugar/should_compile/T4439.run T4439 [exit code non-0] (normal) ghci/scripts/T12007.run T12007 [bad stderr] (ghci) patsyn/should_compile/num.run num [exit code non-0] (normal) patsyn/should_compile/T9732.run T9732 [exit code non-0] (normal) patsyn/should_compile/T9857.run T9857 [exit code non-0] (normal) patsyn/should_compile/T9867.run T9867 [exit code non-0] (normal) patsyn/should_compile/T12698.run T12698 [exit code non-0] (normal) patsyn/should_fail/unboxed-wrapper-naked.run unboxed-wrapper-naked [stderr mismatch] (normal) patsyn/should_run/T9783.run T9783 [exit code non-0] (normal) patsyn/should_run/match-unboxed.run match-unboxed [exit code non-0] (normal) patsyn/should_run/unboxed-wrapper.run unboxed-wrapper [exit code non-0] (normal) They all fail with exactly the same callstack: ghc-stage2: panic! (the 'impossible' happened) (GHC version 8.1.20161022 for x86_64-unknown-linux): ASSERT failed! Infer{apr,2 True} :: TYPE t_apq[tau:2] a_a1pr[tau:2] Call stack: CallStack (from HasCallStack): prettyCurrentCallStack, called at compiler/utils/Outputable.hs:1076:58 in ghc:Outputable callStackDoc, called at compiler/utils/Outputable.hs:1125:22 in ghc:Outputable assertPprPanic, called at compiler/typecheck/TcUnify.hs:547:56 in ghc:TcUnify Call stack: CallStack (from HasCallStack): prettyCurrentCallStack, called at compiler/utils/Outputable.hs:1076:58 in ghc:Outputable callStackDoc, called at compiler/utils/Outputable.hs:1080:37 in ghc:Outputable pprPanic, called at compiler/utils/Outputable.hs:1123:5 in ghc:Outputable assertPprPanic, called at compiler/typecheck/TcUnify.hs:547:56 in ghc:TcUnify Cheers, Erik -- ---------------------------------------------------------------------- Erik de Castro Lopo http://www.mega-nerd.com/