Does not build with clang CPP (-traditional)

[pikajude]

I'm sure you're probably aware of this already, but as of right now it doesn't look like GCC will be usable at all on OS X Yosemite. I'd like to be able to build this package using clang as my compiler.

To clarify, the output from cabal install thyme -j1:

Resolving dependencies...
Configuring thyme-0.3.5.1...
Building thyme-0.3.5.1...
Preprocessing library thyme-0.3.5.1...
[ 1 of 20] Compiling Data.Thyme.Format.Internal ( src/Data/Thyme/Format/Internal.hs, dist/build/Data/Thyme/Format/Internal.o )
Loading package ghc-prim ... linking ... done.
Loading package integer-gmp ... linking ... done.
Loading package base ... linking ... done.
Loading package array-0.5.0.0 ... linking ... done.
Loading package deepseq-1.3.0.2 ... linking ... done.
Loading package containers-0.5.5.1 ... linking ... done.
Loading package pretty-1.1.1.1 ... linking ... done.
Loading package template-haskell ... linking ... done.
Loading package primitive-0.5.3.0 ... linking ... done.
Loading package vector-0.10.11.0 ... linking ... done.
Loading package vector-th-unbox-0.2.1.0 ... linking ... done.
Loading package Boolean-0.2.1 ... linking ... done.
Loading package bytestring-0.10.4.0 ... linking ... done.
Loading package text-1.1.1.3 ... linking ... done.
Loading package hashable-1.2.2.0 ... linking ... done.
Loading package nats-0.2 ... linking ... done.
Loading package unordered-containers-0.2.4.0 ... linking ... done.
Loading package semigroups-0.15.1 ... linking ... done.
Loading package void-0.6.1 ... linking ... done.
Loading package MemoTrie-0.6.2 ... linking ... done.
Loading package NumInstances-1.3 ... linking ... done.
Loading package vector-space-0.8.7 ... linking ... done.
Loading package transformers-0.3.0.0 ... linking ... done.
Loading package transformers-compat-0.3.3.4 ... linking ... done.
Loading package contravariant-0.6 ... linking ... done.
Loading package tagged-0.7.2 ... linking ... done.
Loading package distributive-0.4.4 ... linking ... done.
Loading package comonad-4.2 ... linking ... done.
Loading package semigroupoids-4.0.2.1 ... linking ... done.
Loading package profunctors-4.0.4 ... linking ... done.
Loading package scientific-0.3.2.1 ... linking ... done.
Loading package attoparsec-0.11.3.4 ... linking ... done.
Loading package dlist-0.7.0.1 ... linking ... done.
Loading package mtl-2.1.3.1 ... linking ... done.
Loading package old-locale-1.0.0.6 ... linking ... done.
Loading package syb-0.4.2 ... linking ... done.
Loading package time-1.4.2 ... linking ... done.
Loading package aeson-0.7.0.6 ... linking ... done.
Loading package random-1.0.1.1 ... linking ... done.
Loading package tf-random-0.5 ... linking ... done.
Loading package QuickCheck-2.7.5 ... linking ... done.
[ 2 of 20] Compiling Data.Thyme.Internal.Micro ( src/Data/Thyme/Internal/Micro.hs, dist/build/Data/Thyme/Internal/Micro.o )
[ 3 of 20] Compiling Control.Lens     ( lens/Control/Lens.hs, dist/build/Control/Lens.o )
[ 4 of 20] Compiling Data.Thyme.Calendar.Internal ( src/Data/Thyme/Calendar/Internal.hs, dist/build/Data/Thyme/Calendar/Internal.o )
[ 5 of 20] Compiling Data.Thyme.Clock.Internal ( src/Data/Thyme/Clock/Internal.hs, dist/build/Data/Thyme/Clock/Internal.o )
[ 6 of 20] Compiling Data.Thyme.Calendar.MonthDay ( src/Data/Thyme/Calendar/MonthDay.hs, dist/build/Data/Thyme/Calendar/MonthDay.o )

src/Data/Thyme/Calendar/MonthDay.hs:17:12: parse error on input ‘_’
Failed to install thyme-0.3.5.1
cabal: Error: some packages failed to install:
thyme-0.3.5.1 failed during the building phase. The exception was:
ExitFailure 1

because the LENS macro in thyme.h uses token pasting. clang's preprocessor in traditional mode is not capable of token pasting at all—the empty comment /**/ becomes a space.

[liyang]

I wasn't aware of this... but I am now. Is it possible to invoke Clang's cpp in non-traditional mode and use ## I wonder? I'll take a look when I get some free time, unless you get there before me. ;)

[maoe]

I got the same error. I've fixed it by installing a real gcc (I have gcc-4.9) and editing /path/to/ghc-$version/lib/ghc-$version/settings as follows:

--- /usr/local/ghc/ghc-7.8.2/lib/ghc-7.8.2/settings.orig        2014-07-09 22:40:50.000000000 +0900
+++ /usr/local/ghc/ghc-7.8.2/lib/ghc-7.8.2/settings     2014-07-09 22:41:42.000000000 +0900
@@ -1,5 +1,5 @@
 [("GCC extra via C opts", " -fwrapv"),
- ("C compiler command", "/usr/bin/gcc"),
+ ("C compiler command", "/usr/local/bin/gcc-4.9"),
  ("C compiler flags", " -m64 -fno-stack-protector"),
  ("C compiler link flags", " -m64"),
  ("ld command", "/usr/bin/ld"),

[pikajude]

@maoe: GCC is unusable on 10.10 because it can't parse one of the system header files, which is included by everything in the stdlib.

[pikajude]

It looks like thyme will build successfully with cpphs. I guess we need to push harder on the GHC people to make the compiler use cpphs by default.

[liyang]

Does the above commit fix things on Mavericks? It creates a dependency on cpphs for all Darwin users, but that's probably acceptable.

[maoe]

@liyang I just confirmed that your fix builds fine with vanilla GHC 7.8.2 on Mavericks, but when I ran the tests I got the same error as in the travis build..

[pikajude]

@liyang: as @maoe says, commit fixes the build on Darwin, but causes the Travis failure.

[liyang]

The current Travis failure is due to tests/rewrite.hs being built against an older version of Cabal than what cabal-install uses. I'm not sure how to get it to use the same version…

[liyang]

Released as 0.3.5.2.