[BUG]: Cuda 12.1: error: expected template-name before ‘<’ token

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What version (or hash if on master) of pybind11 are you using?

2.10.4

Problem description

/usr/include/pybind11/detail/../cast.h: In function ‘typename pybind11::detail::type_caster<typename pybind11::detail::intrinsic_type<T>::type
>::cast_op_type<T> pybind11::detail::cast_op(make_caster<T>&)’:
/usr/include/pybind11/detail/../cast.h:45:120: error: expected template-name before ‘<’ token
   45 |     return caster.operator typename make_caster<T>::template cast_op_type<T>();
      |                                                                                                                        ^
/usr/include/pybind11/detail/../cast.h:45:120: error: expected identifier before ‘<’ token
/usr/include/pybind11/detail/../cast.h:45:123: error: expected primary-expression before ‘>’ token
   45 |     return caster.operator typename make_caster<T>::template cast_op_type<T>();
      |                                                                                                                           ^
/usr/include/pybind11/detail/../cast.h:45:126: error: expected primary-expression before ‘)’ token
   45 |     return caster.operator typename make_caster<T>::template cast_op_type<T>();
      |                                                                                                                              ^

Reproducible example code

echo "#include <pybind11/functional.h>" >> t.cu
nvcc -isystem=/usr/include/python3.10 -c t.cu

Is this a regression? Put the last known working version here if it is.

Not a regression

I fixed this by editing /usr/include/pybind11/cast.h:

-    return caster.operator typename make_caster<T>::template cast_op_type<T>();
+    return caster;

It seems nvcc 12.x cannot parse correctly... not sure if this is a nvcc bug, maybe we should just use the unfancy syntax to do the cast, either implicit cast or c-style cast, rather than .operator T...

Add patch to pybind11 to work around pybind/pybind11#4606

I also encounter this issue when I build https://github.com/NVIDIA/apex on ArchLinux with cuda 12.1.0, gcc 12.2.1, pybind11 2.10.4.

/opt/cuda/bin/nvcc -I/usr/lib/python3.10/site-packages/torch/include -I/usr/lib/python3.10/site-packages/torch/include/torch/csrc/api/include -I/usr/lib/python3.10/site-packages/torch/include/TH -I/usr/lib/python3.10/site-packages/torch/include/THC -I/opt/cuda/include -I/usr/include/python3.10 -c csrc/mlp_cuda.cu -o build/temp.linux-x86_64-cpython-310/csrc/mlp_cuda.o -D__CUDA_NO_HALF_OPERATORS__ -D__CUDA_NO_HALF_CONVERSIONS__ -D__CUDA_NO_BFLOAT16_CONVERSIONS__ -D__CUDA_NO_HALF2_OPERATORS__ --expt-relaxed-constexpr --compiler-options '-fPIC' -O3 -DVERSION_GE_1_1 -DVERSION_GE_1_3 -DVERSION_GE_1_5 -DTORCH_API_INCLUDE_EXTENSION_H -DPYBIND11_COMPILER_TYPE=\"_gcc\" -DPYBIND11_STDLIB=\"_libstdcpp\" -DPYBIND11_BUILD_ABI=\"_cxxabi1017\" -DTORCH_EXTENSION_NAME=mlp_cuda -D_GLIBCXX_USE_CXX11_ABI=1 -gencode=arch=compute_75,code=sm_75 -std=c++17
/usr/include/pybind11/detail/../cast.h: In function ‘typename pybind11::detail::type_caster<typename pybind11::detail::intrinsic_type<T>::type>::cast_op_type<T> pybind11::detail::cast_op(make_caster<T>&)’:
/usr/include/pybind11/detail/../cast.h:45:120: error: expected template-name before ‘<’ token
   45 |     return caster.operator typename make_caster<T>::template cast_op_type<T>();
      |                                                                                                                        ^
/usr/include/pybind11/detail/../cast.h:45:120: error: expected identifier before ‘<’ token
/usr/include/pybind11/detail/../cast.h:45:123: error: expected primary-expression before ‘>’ token
   45 |     return caster.operator typename make_caster<T>::template cast_op_type<T>();
      |                                                                                                                           ^
/usr/include/pybind11/detail/../cast.h:45:126: error: expected primary-expression before ‘)’ token
   45 |     return caster.operator typename make_caster<T>::template cast_op_type<T>();
      |                                                                                                                              ^
error: command '/opt/cuda/bin/nvcc' failed with exit code 1

But I could build it with gcc 10.4.0.

I was able to confirm via an NVIDIA contact that this is indeed an nvcc bug and they've opened an internal issue for it.

The takes_ref_wrap and takes_const_ref_wrap tests in test_builtin_casters.cpp fails to compile with the workaround applied:

include/pybind11/detail/../cast.h:47:12: error: invalid initialization of reference of type ‘pybind11::detail::type_caster<ConstRefCasted>::cast_op_type<ConstRefCasted&>’ {aka ‘ConstRefCasted&’} from expression of type ‘pybind11::detail::make_caster<ConstRefCasted&>’ {aka ‘pybind11::detail::type_caster<ConstRefCasted>’}
   47 |     return caster;
      |            ^~~~~~

They also fail to compile with an explicit cast:

include/pybind11/detail/../cast.h:46:12: error: conversion from ‘pybind11::detail::make_caster<const ConstRefCasted&>’ {aka ‘pybind11::detail::type_caster<ConstRefCasted>’} to ‘pybind11::detail::type_caster<ConstRefCasted>::cast_op_type<const ConstRefCasted&>’ {aka ‘const ConstRefCasted&’} is ambiguous
  46 |     return (typename make_caster<T>::template cast_op_type<T>)caster;
     |            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Use GCC 11 in CUDA 12 migrator

Rebuild for CUDA 12 (#40)

I haven't had a chance to test yet, but NVIDIA says that this has been fixed in the recently released 12.2.

Cool, I could confirm that I could build https://github.com/NVIDIA/apex on ArchLinux with cuda 12.2.0, gcc 13.1.1, pybind11 2.10.4.

Use GCC 11 in CUDA 12 migrator

Rebuild for CUDA 12 w/arch support (#44)

Workaround NVCC parse failure in `cast_op`

Workaround NVCC parse failure in `cast_op` (#4893)

Use GCC 11 in CUDA 12 migrator

Use GCC11 in CUDA 12 migrator

I can build https://github.com/NVIDIA/apex with no issue on Debian 12 Bookworm with cuda 12.1.r12.1 and gcc 11.3.0

Use GCC 11 in CUDA 12 migrator

Revert to the upstream CUDA 12 migration

Clean up C build dependencies (and bump Qiskit) (#32)

build: bump nvcc version to 12.2

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[BUG]: Cuda 12.1: error: expected template-name before ‘<’ token #4606

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What version (or hash if on master) of pybind11 are you using?

Problem description

Reproducible example code

Is this a regression? Put the last known working version here if it is.

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[BUG]: Cuda 12.1: error: expected template-name before ‘<’ token #4606

Description

Required prerequisites

What version (or hash if on master) of pybind11 are you using?

Problem description

Reproducible example code

Is this a regression? Put the last known working version here if it is.

Activity

archibate commented on Apr 5, 2023

hubutui commented on Apr 21, 2023

thwalker3 commented on May 12, 2023

cebtenzzre commented on May 31, 2023

thwalker3 commented on Jul 10, 2023

hubutui commented on Jul 11, 2023

serby2000 commented on Nov 18, 2023

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