MaskedMinMax.cu does not compile in CUDA 13.4 due to a const correctness error

[jplzhan]

Two comparison functions declared for finding min and max values with a mask from thrust::tuple were marked as belonging to a struct but were not pedantically marked as const functions. This creates an issue because in CUDA 13.4, the struct hosting the comparison function seems to now be initialized as a const object, so when operator() is called, it creates a compile time error if the operator() is not also marked as a const member function. The offending lines are as follows:

isce3/cxx/isce3/cuda/geocode/MaskedMinMax.cu

Lines 28 to 29 in 404c0de

	__host__ __device__ bool operator()(
	const double_mask lhs, const double_mask rhs)

isce3/cxx/isce3/cuda/geocode/MaskedMinMax.cu

Lines 63 to 64 in 404c0de

	__host__ __device__ bool operator()(
	const double_mask lhs, const double_mask rhs)

The quick solution would be the mark the functions as const after the parameter list, with no other changes.

Here is the beginning of the error in question:

2026-09-25T21:13:32.2244645Z [147/527] Building CUDA object cxx/isce3/cuda/CMakeFiles/isce3-cuda.dir/geocode/MaskedMinMax.cu.o
2026-09-25T21:13:32.2250460Z FAILED: [code=1] cxx/isce3/cuda/CMakeFiles/isce3-cuda.dir/geocode/MaskedMinMax.cu.o 
2026-09-25T21:13:32.2256682Z /home/conda/feedstock_root/build_artifacts/isce3-split_1790370355846/_build_env/bin/nvcc -forward-unknown-to-host-compiler -DISCE3_CUDA -DNDEBUG -DTHRUST_DISABLE_ABI_NAMESPACE -DTHRUST_IGNORE_ABI_NAMESPACE_ERROR -D_FORTIFY_SOURCE=2 -Disce3_cuda_EXPORTS -I/home/conda/feedstock_root/build_artifacts/isce3-split_1790370355846/_build_env/targets/x86_64-linux/include -I/home/conda/feedstock_root/build_artifacts/isce3-split_1790370355846/_build_env/targets/x86_64-linux/include/cccl -I/home/conda/feedstock_root/build_artifacts/isce3-split_1790370355846/work/cxx/isce3/.. -I/home/conda/feedstock_root/build_artifacts/isce3-split_1790370355846/work/build/cxx/isce3/.. -isystem /home/conda/feedstock_root/build_artifacts/isce3-split_1790370355846/_h_env_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold/include/eigen3 -isystem /home/conda/feedstock_root/build_artifacts/isce3-split_1790370355846/_h_env_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold/include --extended-lambda -O3 -DNDEBUG -std=c++17 -arch=all-major -Xcompiler=-fPIC --expt-relaxed-constexpr -Werror=cross-execution-space-call -MD -MT cxx/isce3/cuda/CMakeFiles/isce3-cuda.dir/geocode/MaskedMinMax.cu.o -MF cxx/isce3/cuda/CMakeFiles/isce3-cuda.dir/geocode/MaskedMinMax.cu.o.d -x cu -rdc=true -c /home/conda/feedstock_root/build_artifacts/isce3-split_1790370355846/work/cxx/isce3/cuda/geocode/MaskedMinMax.cu -o cxx/isce3/cuda/CMakeFiles/isce3-cuda.dir/geocode/MaskedMinMax.cu.o
2026-09-25T21:13:32.2263706Z /home/conda/feedstock_root/build_artifacts/isce3-split_1790370355846/_build_env/targets/x86_64-linux/include/cccl/cub/thread/thread_operators.cuh(132): error: no instance of function "isce3::cuda::geocode::masked_min_compare::operator()" matches the argument list and object (the object has type qualifiers that prevent a match)
2026-09-25T21:13:32.2265123Z             argument types are: (const cuda::std::__4::tuple<double, __nv_bool>, const cuda::std::__4::tuple<double, __nv_bool>)
2026-09-25T21:13:32.2265833Z             object type is: const isce3::cuda::geocode::masked_min_compare
2026-09-25T21:13:32.2266498Z       if (less(b.value, a.value) || (!less(a.value, b.value) && b.key < a.key))
2026-09-25T21:13:32.2266928Z           ^

object type is: const isce3::cuda::geocode::masked_min_compare I believe indicates that the object cannot call operator() as it is not an explicitly const member function.