[GHC] #13553: GHC 8.2.1 preprocesses __GLASGOW_HASKELL__ incorrectly with cpphs
GHC
ghc-devs at haskell.org
Sun Apr 9 14:56:44 UTC 2017
#13553: GHC 8.2.1 preprocesses __GLASGOW_HASKELL__ incorrectly with cpphs
-------------------------------------+-------------------------------------
Reporter: RyanGlScott | Owner: (none)
Type: bug | Status: new
Priority: normal | Milestone:
Component: Compiler | Version: 8.1
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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I'm not exactly sure if this is the fault of `cpphs` or GHC, but I'll
report this issue to GHC Trac for now, since (ostensibly) the only thing
that has changed in this equation is the GHC version. Take this file:
{{{#!hs
{-# LANGUAGE CPP #-}
module Bug where
foo :: Int
#if __GLASGOW_HASKELL__ >= 800
foo = 42
#else
foo = "wrong type"
#endif
}}}
Now let's compile it using `cpphs-1.20.4` as a preprocessor. With GHC 8.0,
everything works out fine:
{{{
$ /opt/ghc/8.0.2/bin/ghc Bug.hs -pgmP cpphs -optP --cpp
Warning: Can't find file
"/opt/ghc/8.0.2/lib/ghc-8.0.2/include/ghcversion.h" in directories
Asked for by: Bug.hs at line 1 col 1
[1 of 1] Compiling Bug ( Bug.hs, Bug.o )
}}}
But with GHC 8.2.1, things go awry:
{{{
$ /opt/ghc/8.2.1/bin/ghc Bug.hs -pgmP cpphs -optP --cpp
Warning: Can't find file
"/opt/ghc/8.2.1/lib/ghc-8.2.0.20170403/include/ghcversion.h" in
directories
Asked for by: Bug.hs at line 1 col 1
[1 of 1] Compiling Bug ( Bug.hs, Bug.o )
Bug.hs:8:7: error:
• Couldn't match expected type ‘Int’ with actual type ‘[Char]’
• In the expression: "wrong type"
In an equation for ‘foo’: foo = "wrong type"
|
8 | foo = "wrong type"
| ^^^^^^^^^^^^
}}}
This bug causes several libraries on Hackage which use `cpphs` as a
preprocessor to fail when built with GHC 8.2.1, including `Agda`.
--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13553>
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