Fedora 43 and NVCC / Cuda13.1 error "exception specification is incompatible" rsqrt / rsqrtf

Accelerated Computing CUDA CUDA Setup and Installation
1

If you are facing errors like the following when trying to complie applications with NVCC / CUDA 13.1 on Fedora 43


/usr/include/bits/mathcalls.h(206): error: exception specification is
  incompatible with that of previous function "rsqrt" (declared at line 629
  of
  /usr/local/cuda/bin/../targets/x86_64-linux/include/crt/math_functions.h)
    extern double rsqrt (double __x) noexcept (true); extern double __rsqrt (double __x) noexcept (true);
                                     ^

  /usr/include/bits/mathcalls.h(206): error: exception specification is
  incompatible with that of previous function "rsqrtf" (declared at line 653
  of
  /usr/local/cuda/bin/../targets/x86_64-linux/include/crt/math_functions.h)
    extern float rsqrtf (float __x) noexcept (true); extern float __rsqrtf (float __x) noexcept (true);
                                    ^

Its likely due to the fact that glibc’s <math.h> declares rsqrt with noexcept(true), but CUDA’s headers declare it without noexcept (or with a different exception specification).

GCC 14 + glibc are now providing rsqrt/rsqrtf in the standard math library, and there’s a conflict with CUDA’s declarations.

The simplest path is to modify the CUDA headers for math_functions.h to match the glibc math.h headers. The following worked for me

sudo patch -b /usr/local/cuda/targets/x86_64-linux/include/crt/math_functions.h << 'EOF'
--- a/math_functions.h
+++ b/math_functions.h
@@ -626,7 +626,7 @@
  *
  * \note_accuracy_double
  */
-extern __DEVICE_FUNCTIONS_DECL__ __device_builtin__ double                 rsqrt(double x);
+extern __DEVICE_FUNCTIONS_DECL__ __device_builtin__ double                 rsqrt(double x) noexcept (true);
 
 /**
  * \ingroup CUDA_MATH_SINGLE
@@ -650,7 +650,7 @@
  *
  * \note_accuracy_single
  */
-extern __DEVICE_FUNCTIONS_DECL__ __device_builtin__ float                  rsqrtf(float x);
+extern __DEVICE_FUNCTIONS_DECL__ __device_builtin__ float                  rsqrtf(float x) noexcept (true);
 
 #if defined(__QNX__) && !defined(_LIBCPP_VERSION)
 namespace std {
EOF

Hope its helpful for others

2 Likes