Repeated "impossible" go_axiom_rule error.
I am getting the following error repeatedly:
ghc: panic! (the 'impossible' happened)
(GHC version 8.4.1 for x86_64-unknown-linux):
go_axiom_rule
Sub0R
Call stack:
CallStack (from HasCallStack):
callStackDoc, called at compiler/utils/Outputable.hs:1150:37 in ghc:Outputable
pprPanic, called at compiler/iface/TcIface.hs:1371:15 in ghc:TcIface
I got it on 8.2.1, and tried upgrading to 8.4.1 to see if it went away, but it did not.
It occurs frequently when I do a --make
and recompile a subset of modules. I can avoid it by force-recompiling all modules, although of course this is inefficient.
Since I'm working with a codebase of thousands of lines and don't understand ghc's innards, I'm not sure where to start looking for the cause, to produce a minimal failing example. But it did start happening around the time I expanded my use of this module:
https://github.com/agrafix/superrecord
Since there are unsafe operations in there, it is possible it is doing something illicit, but it is hard to see how it would cause this.
Trac metadata
Trac field | Value |
---|---|
Version | 8.4.1 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler |
Test case | |
Differential revisions | |
BlockedBy | |
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Blocking | |
CC | |
Operating system | |
Architecture |