Check for GCC <= 4.9 before compiling

[bforsbe]

Originally reported by: Dimitry Tegunov (Bitbucket: DTegunov, GitHub: DTegunov)

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I think a few help requests could be avoided in the future if cmake made sure GCC's version (though there are probably similar issues with other compilers?) is <= the maximum supported by the CUDA SDK, before make is executed. Especially when running the latter with many threads, NVCC's complaints about GCC can be hard to find.

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• Bitbucket: https://bitbucket.org/tcblab/relion2-beta/issue/14

[bforsbe]

Original comment by Bjoern Forsberg (Bitbucket: bforsbe, GitHub: bforsbe):

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I agree this would be ideal. However, the supported version of compiler (especially for GCC) depends not only on your CUDA-version but also on you OS. We should put in a warning about using GCC versions higher than 4.x, but for now I think the user should be able to use the CUDA-toolkit documentation about supported compilers to figure out what is needed. But we could definitely include this table in the manual or on the RELION wiki, so that this information is easily accessible when following installation instructions.

[bforsbe]

Original comment by Jon Diprose (Bitbucket: well-jon, GitHub: Unknown):

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I'd rather the restriction only applied for CUDA-enabled builds. Not that I'm using a gcc5 but still, if it's a CUDA-imposed limit the check should only be made if CUDA is being used. Unless other things have problems with gcc5!

[bforsbe]

Original comment by Erik Lindahl (Bitbucket: eriklindahl, GitHub: eriklindahl):

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The problem is that CUDA evolves rapidly, and if we add a warning e.g. for gcc-5.0 that is going to be invalid already within weeks when NVIDIA releases CUDA-8.0.

We should thus not warn about specific compiler versions, but the one thing we could do is to try and compile a trivial CUDA program to make sure that works with the selected compiler and CUDA version.

[bforsbe]

Original comment by cameron kennedy (Bitbucket: cdk, GitHub: cdk):

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We seen this failure on our newer boxes, and machines with updated gcc.
To build, we removed the gcc version check.
We did this by editing $CUDA_DIR/include/host_config.h and commenting out the check for gcc version.

#if GNUC > 4 || (GNUC == 4 && GNUC_MINOR > 9)

// #error -- unsupported GNU version! gcc versions later than 4.9 are not supported!

#endif /* GNUC > 4 || (GNUC == 4 && GNUC_MINOR > 9) */

[bforsbe]

Original comment by Bjoern Forsberg (Bitbucket: bforsbe, GitHub: bforsbe):

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Could implement test-compilation and/or CUDA-dep gcc version-check, but that will await stable CUDA 8.0 recommendation at the very least.