Compiling pandoc-2.9.2.1 on GHC HEAD panics (applyTypeToArgs)
Originally observed on a head.hackage
CI build here.
Attempting to compile pandoc-2.9.2.1
on GHC HEAD will result in the following panic:
[106 of 166] Compiling Text.Pandoc.Writers.Docx
ghc: panic! (the 'impossible' happened)
(GHC version 8.11.0.20200403:
applyTypeToArgs
Expression: wild_a3j6U ys_a1Q2
Type: Element
Args: [ys_a1Q2]
Call stack:
CallStack (from HasCallStack):
callStackDoc, called at compiler/utils/Outputable.hs:1228:37 in ghc:Outputable
pprPanic, called at compiler/GHC/Core/Utils.hs:237:14 in ghc:GHC.Core.Utils
Unfortunately, the code that triggers the panic is quite massive, and I have had no luck attempting to minimize it. I did confirm that the commit that caused this regression is b943b25d (Re-engineer the binder-swap transformation
), however.