[GHC] #16095: Infinite loop during error reporting (ignores SIGINT/SIGTERM, then OOMs)

[GHC]

#16095: Infinite loop during error reporting (ignores SIGINT/SIGTERM, then OOMs)
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        Reporter:  _deepfire         |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.6.1
      Resolution:                    |             Keywords:
Operating System:  Linux             |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  crash or panic                     |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Description changed by _deepfire:

Old description:

> Compiling the repro snippet produces the following incomplete output and
> hangs GHC:
> {{{
> $ ghc repro.hs
> [1 of 1] Compiling Main             ( repro.hs, repro.o )
>
> repro.hs:16:22: error:
> }}}
>
> The GHC process ignores SIGINT -- so it must be killed with SIGKILL.
> The memory usage grows, until it consumes all memory (~30G RAM + swap)
> and is terminated by the OOM killer.
>
> This minimal snippet depends on `generics-sop` (tested with version
> `0.4.0.0`).
> Sadly I didn't find a constraint in `base` to cause this behavior..
>
> {{{#!hs
> {-# LANGUAGE FlexibleInstances #-}
> {-# LANGUAGE MultiParamTypeClasses #-}
> {-# LANGUAGE TypeFamilies #-}
>
> import Generics.SOP (HasDatatypeInfo)
>
> data family   TF i a :: *
> data instance TF i a = R
>
> class C i a where
>   method :: TF i a
>
> instance C i () where
>
> instance HasDatatypeInfo a => C i a where
>   method = undefined function
>
> function :: C i a => TF i a
> function = method
>
> main = undefined
> }}}

New description:

 Compiling the repro snippet produces the following incomplete output and
 hangs GHC:
 {{{
 $ ghc repro.hs
 [1 of 1] Compiling Main             ( repro.hs, repro.o )

 repro.hs:16:22: error:
 }}}

 The GHC process ignores SIGINT -- so it must be killed with SIGKILL.
 The memory usage grows, until it consumes all memory (~30G RAM + swap) and
 is terminated by the OOM killer.

 This minimal snippet depends on `generics-sop` (tested with version
 `0.4.0.0`).
 Sadly I didn't find a constraint in `base` to cause this behavior..

 {{{#!hs
 {-# LANGUAGE FlexibleInstances #-}
 {-# LANGUAGE MultiParamTypeClasses #-}
 {-# LANGUAGE TypeFamilies #-}

 import Generics.SOP (HasDatatypeInfo)

 data family   TF i a :: *
 data instance TF i a = R

 class C i a where
   method :: TF i a

 instance C i () where

 instance HasDatatypeInfo a => C i a where
   method = undefined function

 function :: C i a => TF i a
 function = method

 main = undefined
 }}}

 Affects 8.4.3 and 8.6.1.

 Not tested on 8.6.2 & 8.6.3.

--

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16095#comment:2>
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