NVCC fails with the error ""_GLIBCXX_MATH_H" is not defined"

Question

I'm compiling a CUDA program - a simple and innocuous one. Regardless of how far I simplify it or remove some of the code or the include files, nvcc tells me:

In file included from /usr/local/cuda/bin/..//include/crt/common_functions.h:271:0,
                 from /usr/local/cuda/bin/..//include/common_functions.h:50,
                 from /usr/local/cuda/bin/..//include/cuda_runtime.h:115,
                 from <command-line>:0:
/usr/local/cuda/bin/..//include/crt/math_functions.h:8891:5: error: "_GLIBCXX_MATH_H" is not defined [-Werror=undef]

I'm using CUDA 9.0 or 9.1 on Linux, and CUDA is using GCC (either 5 or 6). Why is this happening and how can I fix it?

@RobertCrovella: Not really, because I want to make it clear that the answer is relevant to many such cases and not to a very specific example. — einpoklum, Feb 06 '18 at 23:52
@einpoklum: The problem with that is that I have CUDA 9 and CUDA 9.1 and every supported gcc and clang version installed on the platform I use and I have *never* gotten that warning. Ever. — talonmies, Feb 07 '18 at 06:06
@talonmies: Try building ModernGPU and you'll get it (see the [Makefile](https://github.com/moderngpu/moderngpu/blob/master/Makefile)). — einpoklum, Feb 07 '18 at 10:29
@einpoklum: But below you said that an empty main will trigger this error. Which is it? — talonmies, Feb 07 '18 at 10:32
@talonmies: Both - it's about the compiler flags, not the source. ModernGPU has this problematic choice of compiler flags. — einpoklum, Feb 07 '18 at 10:34

einpoklum · Accepted Answer · 2018-02-07T10:35:10.540

tl;dr: Change your problematic compilation flags.

In CUDA 9.0 and 9.1, nVIDIA is a bit sloppy about using certain macros before checking they've been defined. That is, indeed, a sort-of-an issue with the header files crt/math_functions.h, crt/math_functions.hpp and math_functions.hpp (in the CUDA include directory).

However, this is usually not an actual problem, since an undefined macro defaults to a value of 0 (in C and probably in C++ too). And indeed, by default, neither gcc nor nvcc will complain.

In your case, however, something is making GCC run with -Wundef, which warns you about these cases, and -Werror, which escalates all warnings into errors. Since what you're invoking is nvcc, the command-line (which you, likely, did not write yourself) probably has -Xcompiler="-Wundef" and -Xcompiler="-Werror" somewhere.

Removing the latter of these two will make nvcc succeed (barring other errors), and removing both will make the warnings go away as well.

@talonmies: Nope. Actually, the code could be simply `int main() { }` and that's it. — einpoklum, Feb 06 '18 at 23:52

NVCC fails with the error ""_GLIBCXX_MATH_H" is not defined"

1 Answers1

tl;dr: Change your problematic compilation flags.