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clash-lang / clash-compiler

Haskell to VHDL/Verilog/SystemVerilog compiler
https://clash-lang.org/
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panic! Please don't report as a ghc bug #496

Open martijnbastiaan opened 5 years ago

martijnbastiaan commented 5 years ago

Every once in a while a Clash bug rears its head telling user to file a bug at the Haskell bug tracker. For example:

          clash: panic! (the 'impossible' happened)
            (GHC version 8.6.3 for x86_64-unknown-linux):
            Clash.Netlist.BlackBox(173): Forced to evaluate untranslatable type: (λ($dIP8214565720323859278 :: GHC.Classes.IP
                                         callStack
                                         GHC.Stack.Types.CallStack) ->
          λ(eta8214565720323859279 :: GHC.Types.[]
                                        GHC.Types.Char) ->
          case $dIP8214565720323859278 of
            _ ->
              Clash.XException.errorX
                @(Clash.Sized.Internal.Unsigned.Unsigned 4)
                (Clash.Transformations.removedArg
                   @(GHC.Classes.IP
                       callStack
                       GHC.Stack.Types.CallStack))
                (Clash.Transformations.removedArg
                   @(GHC.Types.[] GHC.Types.Char))
            GHC.Stack.Types.FreezeCallStack8214565720323839287 
              (ds18214565720323859282 :: GHC.Stack.Types.CallStack) ->
              Clash.XException.errorX
                @(Clash.Sized.Internal.Unsigned.Unsigned 4)
                (Clash.Transformations.removedArg
                   @(GHC.Classes.IP
                       callStack
                       GHC.Stack.Types.CallStack))
                (Clash.Transformations.removedArg
                   @(GHC.Types.[] GHC.Types.Char)) :: GHC.Classes.IP
            callStack
            GHC.Stack.Types.CallStack
          -> GHC.Types.[] GHC.Types.Char
          -> Clash.Sized.Internal.Unsigned.Unsigned 4)
          CallStack (from HasCallStack):
            error, called at src/Clash/Netlist/BlackBox.hs:173:21 in clash-lib-0.99-inplace:Clash.Netlist.BlackBox

          Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug

          Stdout was:
          Loading dependencies took 2.274103764s
          Parsing and compiling primitives took 7.041263846s
          Compiling: BlockRamTest.topEntity
          Normalisation took 7.053837786s

We should never redirect users to the Haskell bug tracker. Because we can't feasibly foresee when this message will be reported, we should simply filter our output and replace it with a less offensive message.

christiaanb commented 4 years ago

@martijnbastiaan Is there any reproducible test case for this?

martijnbastiaan commented 4 years ago

I think this might still happen if Clash throws an error instead of ClashException? Maybe you could try adding an error call somewhere. If we can't reproduce it I guess we can close this issue and tag it with 'non-reproducable'.

christiaanb commented 4 years ago

handleClashException should catch the exceptions.

To try to reproduce the error, I changed the blackbox for blockram to bogusly use its HasCallStack argument, but handleClashException picked it up correctly.

Hence I'm moving this to 1.4