[GHC] #14574: Template Haskell Uniq ~ Int leads to external interpreter cross compilation trouble

[GHC]

#14574: Template Haskell Uniq ~ Int leads to external interpreter cross compilation
trouble
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           Reporter:  luite          |             Owner:  (none)
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  8.3
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  None/Unknown
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
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 64 bit GHC has 64 bit Unique values, but they don't fit in a `template-
 haskell` `NameU` when cross-compiling to a 32 bit target.

 In theory we can support Template Haskell in this situation with
 `-fexternal-interpreter` (and the earlier GHCJS implementation), but when
 the target cannot represent GHC's uniques in an `Int`, things go wrong:

 from `Language.Haskell.TH.Syntax`:
 {{{#!hs
 type Uniq = Int
 }}}

 I think we can fix this for now by changing the synonym to `type Uniq =
 Int64` (or even `type Uniq = Integer`), making the `template-haskell`
 `Uniq` at least as big as the GHC `Unique` in practice. This requires a
 change in `DsMeta`.

 the uses of `Int` below should really be changed to `Uniq`

 {{{#!hs
 data NameFlavour
   = NameS           -- ^ An unqualified name; dynamically bound
   | NameQ ModName   -- ^ A qualified name; dynamically bound
   | NameU !Int      -- ^ A unique local name
   | NameL !Int      -- ^ Local name bound outside of the TH AST
   | NameG NameSpace PkgName ModName -- ^ Global name bound outside of the
 TH AST:
                 -- An original name (occurrences only, not binders)
                 -- Need the namespace too to be sure which
                 -- thing we are naming
   deriving ( Data, Eq, Ord, Show, Generic )
 }}}

 {{{#!hs
 -- Global variable to generate unique symbols
 counter :: IORef Int
 {-# NOINLINE counter #-}
 counter = unsafePerformIO (newIORef 0)
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14574>
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