stage2 build fails

[Simon Peyton Jones]

|  Indeed it would be nice to know which compiler you are using to
|  bootstrap. I suspect Sylvain is correct that the alternative can be
|  removed but first I would like to understand why this is arising only
|  now.

I'm using 8.6.4 as my bootstrap compiler. But this message occurs only when compiling the *stage2* compiler with the *stage1* compiler. At that moment the bootstrap compiler is irrelevant.

It's as if the build system doesn't know that the stage1 compiler is >= 8.10

Simon

|  -----Original Message-----
|  From: Ben Gamari <ben at smart-cactus.org>
|  Sent: 27 January 2020 14:51
|  To: Simon Peyton Jones <simonpj at microsoft.com>; ghc-devs <ghc-
|  devs at haskell.org>
|  Subject: Re: stage2 build fails
|  
|  Simon Peyton Jones via ghc-devs <ghc-devs at haskell.org> writes:
|  
|  > I'm getting this with "sh validate -legacy"
|  >
|  > compiler/main/DynFlags.hs:1344:15: error: [-Woverlapping-patterns, -
|  Werror=overlapping-patterns]
|  >
|  >     Pattern match is redundant
|  >
|  >     In an equation for 'settings': settings s | otherwise = ...
|  >
|  >      |
|  >
|  > 1344 |             | otherwise = panic $ "Invalid cfg parameters." ++
|  exampleString
|  >
|  >      |               ^^^^^^^^^
|  > This is when compiling the stage-2 compiler.  There's an ifdef in
|  DynFlags thus
|  >
|  > #if __GLASGOW_HASKELL__ <= 810
|  >
|  >             | otherwise = panic $ "Invalid cfg parameters." ++
|  exampleString
|  >
|  > #endif
|  > but somehow it's not triggering for the stage2 compiler.
|  > Any ideas?  It's blocking a full build.
|  > This #ifdef was added in 8038cbd96f4, when GHC became better at
|  reporting redundant code.
|  > Simon
|  
|  Indeed it would be nice to know which compiler you are using to
|  bootstrap. I suspect Sylvain is correct that the alternative can be
|  removed but first I would like to understand why this is arising only
|  now.
|  
|  Cheers,
|  
|  - Ben