[GHC] #8519: Make -XTemplateHaskell an error in a stage-1 compiler
GHC
ghc-devs at haskell.org
Mon Nov 11 08:50:52 UTC 2013
#8519: Make -XTemplateHaskell an error in a stage-1 compiler
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Reporter: simonpj | Owner:
Type: bug | Status: new
Priority: normal | Milestone:
Component: Compiler | Version: 7.6.3
Keywords: | Operating System: Unknown/Multiple
Architecture: Unknown/Multiple | Type of failure: None/Unknown
Difficulty: Unknown | Test Case:
Blocked By: | Blocking:
Related Tickets: |
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If you use the language extension `-XTemplateHaskell` in a stage-1
compiler, it's guaranteed not to work. This patch makes it an error to do
so.
The error is suppressed in `MkDepend` mode (i.e. `ghc -M`) because that
''does'' work; the TH flag is not consulted.
Moreover it is used by GHC's build system itself: for some reason we use
the stage-1 compiler to do build the `.depend` files for DPH, even though
DPH is only built with stage2. This is an infelicity, but Ian writes
"It's due to the
[wiki:Building/Architecture/Idiom/PhaseOrdering#GHCsphases build system
phases]: stage2 doesn't exist during the phase in which DPH is configured.
Changing it to use stage 2 would probably mean adding another phase for
things that need to be configured by stage 2. This might mean slower
builds due to loss of parallelism, I'm not sure.
This change isn't mission critical; it could be a warning instead.
--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8519>
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