Stack: Hfsevents not building, Objective-C not recognized

[brandonchinn178]

I'm getting an error building hfsevents. More details found here. Can anyone help?

[luigy]

I already followed the advice of calling brew install gcc48 --with-all-languages and I uninstalled all Haskell versions, only using the ghc within stack.

It builds fine for me just using gcc from xcode-select --install, but I'm on El Capitan
But even in Yosemite I don't think gcc48 from homebrew would be necessary, though

[brandonchinn178]

I'm on Yosemite, and my Xcode is up to date. The strangest thing was, it was working before, but it suddenly stopped working and I don't remember doing anything to mess with gcc.

[luigy]

Very odd. I would uninstall gcc48 and reinstall command line tools using xcode-select --install and try building it again. Paste a link to a paste of the verbose output if it fails again :)

[brandonchinn178]

Brandon: ~/path/to/project/ (git:master)
(env)$ brew uninstall gcc48
Uninstalling /usr/local/Cellar/gcc48/4.8.4... (4862 files, 354M)

Brandon: ~/path/to/project/ (git:master)
(env)$ xcode-select --install
xcode-select: error: command line tools are already installed, use "Software Update" to install updates

Brandon: ~/path/to/project/ (git:master)
(env)$ stack build
hfsevents-0.1.6: configure
tf-random-0.5: download
text-binary-0.2.1: download
cpphs-1.19.3: download
hfsevents-0.1.6: build
text-binary-0.2.1: configure
text-binary-0.2.1: build
tf-random-0.5: configure
text-binary-0.2.1: copy/register
transformers-compat-0.4.0.4: copying precompiled package
tf-random-0.5: build
cpphs-1.19.3: configure
cpphs-1.19.3: build
MonadRandom-0.4.1: configure
MonadRandom-0.4.1: build
MonadRandom-0.4.1: copy/register
tf-random-0.5: copy/register
cpphs-1.19.3: copy/register
Progress: 6/85
--  While building package hfsevents-0.1.6 using:
      /Users/Brandon/.stack/setup-exe-cache/x86_64-osx/setup-Simple-Cabal-1.22.4.0-ghc-7.10.2 --builddir=.stack-work/dist/x86_64-osx/Cabal-1.22.4.0 build --ghc-options " -ddump-hi -ddump-to-file"
    Process exited with code: ExitFailure 1
    Logs have been written to: /Users/Brandon/path/to/project/.stack-work/logs/hfsevents-0.1.6.log

    Configuring hfsevents-0.1.6...
    Building hfsevents-0.1.6...
    Preprocessing library hfsevents-0.1.6...
    [1 of 1] Compiling System.OSX.FSEvents ( System/OSX/FSEvents.hs, .stack-work/dist/x86_64-osx/Cabal-1.22.4.0/build/System/OSX/FSEvents.o )
    gcc: error: language objective-c not recognized
    gcc: error: language objective-c not recognized

[borsboom]

I'm on Yosemite with Xcode 7.2 and have no trouble installing hfsevents. This sounds like a system problem and not something specific to Stack. I'd be curious whether cabal-install fares better (e.g. try running cabal install hfsevents).

[brandonchinn178]

cabal install hfsevents works, but stack is still not working. could it be some PATH issue, where stack builds on some other PATH?

[borsboom]

Yes, I'd suggest using stack --verbose and comparing the arguments passed to ghc with the verbose output from cabal-install to see what might be different.

[luigy]

and perhaps the output of stack exec -- ghc --info and which -a gcc are also useful

[brandonchinn178]

Ok. So cabal install hfsevents -v had the line /usr/bin/gcc -dumpversion whereas stack exec -- ghc --info included the line ("C compiler command","/usr/local/bin/gcc"). However, /usr/local/bin/gcc -dumpversion gave me 4.9.2 and /usr/bin/gcc -dumpversion gave me 4.2.1. Why would the older version work and not the newer one?

Should I just change the gcc stack is using? How do I update the settings for stack's ghc?

[luigy]

Why would the older version work and not the newer one?

Most likely /usr/local/bin/gcc -v does not have objc lang enabled and it is probably better rm it to avoid future compilers installed by stack from picking it up?

Should I just change the gcc stack is using? How do I update the settings for stack's ghc?

I would make sure stack is using a ghc installed by it and this steps should help updating the c compiler

[brandonchinn178]

Ah yes, removing /usr/local/bin/gcc worked. I guess since XCode installed the /usr/bin/gcc executable, it's better to use that one anyway. Thanks!