configuring gcc path seems not to work as intended for dependencies

[simonjantsch]

Pullrequest #2264 added an option to specify which gcc should be used by stack when building a project. I tried this with a project that requires a specific gcc version to build a dependency and it still seems to use the global gcc in $PATH.

The project I'm trying to build is: https://github.com/simonjantsch/vvt

When running stack clean; stack build --verbose --cabal-verbose I get the output in the attached file. bindings-llvm is the relevant dependency.
stack.txt

When manually changing the gcc in path to the right one (gcc version 4.9.3 works for instance) the project compiles.

[sjakobi]

Which gcc version is the build supposed to fail with?

[sjakobi]

When using --with-gcc /usr/bin/gcc-4.8 I already get a compile failure for bindings-llvm's custom Setup.hs which, so I suspect, isn't compatible with Cabal-1.24… :(

[sjakobi]

Ok, using Cabal-1.22.5.0 I get a bit further until

    Configuring bindings-llvm-0.1...
    Warning: Instead of 'ghc-options: -cpp -cpp' use 'extensions: CPP CPP'
    setup: The program 'llvm-config' is required but it could not be found.

I can see though that the --with-gcc option is correctly passed to the various setup configure calls, so I'm currently assuming that some other issue is at play in either bindings-llvm or vvt.

@simonjantsch: Can you build your project with cabal --with-gcc and the "wrong" gcc on the PATH?

I'd also be more convinced of a problem with stack if someone could demonstrate the problem on a different project that doesn't use bindings-llvm.

[simonjantsch]

@Sjakob After looking at this again I believe your right, this has something to do with the llvm-config invoking gcc. Too bad, I was hoping for this to fix my issue. I'm closing the issue, thanks for the support!