[GHC] #15708: Cross-module SPECIALZE pragmas aren't typechecked in -O0

[GHC]

#15708: Cross-module SPECIALZE pragmas aren't typechecked in -O0
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        Reporter:  regnat            |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler (Type    |              Version:  8.6.1
  checker)                           |
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  GHC accepts       |  Unknown/Multiple
  invalid program                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by regnat):

 > without -O we just treat SPECIALISE pragmas as comments.

 That seems not to be exactly the case in practice: if the SPECIALISE
 pragma is in the same module as the definition then I get an error.

 Regardless of that, I find this a bit surprising: I would have expected
 that as much as possible whether a program is valid or not doesn't depend
 on the optimization level (which obviously isn't possible to guaranty in
 the general case because of things like the RULE pragma, but as you
 mentioned this doesn't cost much to check). Or do I overlook another good
 reason for not typechecking these pragmas?

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15708#comment:2>
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