Trying to compile OpenCL 1.2 example

Question

System:

Ryzen 1600, r9 270 (radeon driver), ubuntu 16.04

I'm trying to get my compiler (gcc 5.4.1) to compile some C++ with OpenCL but can't get it to find the header files.

test.cpp:

    #include <CL/cl.hpp>
    int main(){}

I run g++ test.cpp -lOpenCL but get fatal error: CL/cl.hpp: No such file or directory.

For other people with the same issue on StackOverflow, the issue was libOpenCL was not installed. But I have, I installed all these packages:

opencl-headers, ocl-icd-opencl-dev, ocl-icd-libopencl1, mesa-opencl-icd, clinfo, libclc-dev, libclc-amdgcn, libclcr600 (searched 'opencl' in synaptic)

And running "locate libOpenCL" gives many entries including "/usr/local/lib/libOpenCL.so" which should be picked up by the -lOpenCL flag??

clinfo gives:

Number of platforms                               1
  Platform Name                                   Clover
  Platform Vendor                                 Mesa
  Platform Version                                OpenCL 1.1 Mesa 17.2.8
  Platform Profile                                FULL_PROFILE
  Platform Extensions                             cl_khr_icd
  Platform Extensions function suffix             MESA

  Platform Name                                   Clover
Number of devices                                 1
  Device Name                                     AMD PITCAIRN (DRM 2.50.0 / 4.13.0-37-generic, LLVM 5.0.0)
  Device Vendor                                   AMD
  Device Vendor ID                                0x1002
  Device Version                                  OpenCL 1.1 Mesa 17.2.8
  Driver Version                                  17.2.8
  Device OpenCL C Version                         OpenCL C 1.1 
  Device Type                                     GPU
  Device Profile                                  FULL_PROFILE
  Max compute units                               20
  Max clock frequency                             955MHz
  Max work item dimensions                        3
  Max work item sizes                             256x256x256
  Max work group size                             256
  Preferred work group size multiple              64
  Preferred / native vector sizes                 
    char                                                16 / 16      
    short                                                8 / 8       
    int                                                  4 / 4       
    long                                                 2 / 2       
    half                                                 0 / 0        (n/a)
    float                                                4 / 4       
    double                                               2 / 2        (cl_khr_fp64)
  Half-precision Floating-point support           (n/a)
  Single-precision Floating-point support         (core)
    Denormals                                     No
    Infinity and NANs                             Yes
    Round to nearest                              Yes
    Round to zero                                 No
    Round to infinity                             No
    IEEE754-2008 fused multiply-add               No
    Support is emulated in software               No
    Correctly-rounded divide and sqrt operations  No
  Double-precision Floating-point support         (cl_khr_fp64)
    Denormals                                     Yes
    Infinity and NANs                             Yes
    Round to nearest                              Yes
    Round to zero                                 Yes
    Round to infinity                             Yes
    IEEE754-2008 fused multiply-add               Yes
    Support is emulated in software               No
    Correctly-rounded divide and sqrt operations  No
  Address bits                                    64, Little-Endian
  Global memory size                              2147483648 (2GiB)
  Error Correction support                        No
  Max memory allocation                           1503238553 (1.4GiB)
  Unified memory for Host and Device              No
  Minimum alignment for any data type             128 bytes
  Alignment of base address                       1024 bits (128 bytes)
  Global Memory cache type                        None
  Image support                                   No
  Local memory type                               Local
  Local memory size                               32768 (32KiB)
  Max constant buffer size                        1503238553 (1.4GiB)
  Max number of constant args                     16
  Max size of kernel argument                     1024
  Queue properties                                
    Out-of-order execution                        No
    Profiling                                     Yes
  Profiling timer resolution                      0ns
  Execution capabilities                          
    Run OpenCL kernels                            Yes
    Run native kernels                            No
  Device Available                                Yes
  Compiler Available                              Yes
  Device Extensions                               cl_khr_global_int32_base_atomics cl_khr_global_int32_extended_atomics cl_khr_local_int32_base_atomics cl_khr_local_int32_extended_atomics cl_khr_byte_addressable_store cl_khr_fp64

NULL platform behavior
  clGetPlatformInfo(NULL, CL_PLATFORM_NAME, ...)  Clover
  clGetDeviceIDs(NULL, CL_DEVICE_TYPE_ALL, ...)   Success [MESA]
  clCreateContext(NULL, ...) [default]            Success [MESA]
  clCreateContextFromType(NULL, CL_DEVICE_TYPE_CPU)  No devices found in platform
  clCreateContextFromType(NULL, CL_DEVICE_TYPE_GPU)  Success (1)
    Platform Name                                 Clover
    Device Name                                   AMD PITCAIRN (DRM 2.50.0 / 4.13.0-37-generic, LLVM 5.0.0)
  clCreateContextFromType(NULL, CL_DEVICE_TYPE_ACCELERATOR)  No devices found in platform
  clCreateContextFromType(NULL, CL_DEVICE_TYPE_CUSTOM)  No devices found in platform
  clCreateContextFromType(NULL, CL_DEVICE_TYPE_ALL)  Success (1)
    Platform Name                                 Clover
    Device Name                                   AMD PITCAIRN (DRM 2.50.0 / 4.13.0-37-generic, LLVM 5.0.0)

ICD loader properties
  ICD loader Name                                 OpenCL ICD Loader
  ICD loader Vendor                               OCL Icd free software
  ICD loader Version                              2.2.8
  ICD loader Profile                              OpenCL 1.2
        NOTE:   your OpenCL library declares to support OpenCL 1.2,
                but it seems to support up to OpenCL 2.1 too.

Answer 1

On Linux, you need a package commonly named opencl-headers. Also note that different OpenCL versions are incompatible, so if your example is 1.2 you need to ensure that the headers are also 1.2

Answer 2

You want to download cl.hpp from here: https://www.khronos.org/registry/OpenCL/api/2.1/cl.hpp. And make sure you link to OpenCL.

OpenCL is a C-style API, so lots of functions for playing with pointers to ints.

cl.hpp is a C++ style API, so lots of classes with readable methods for playing with pointers to ints.

They are seperate things.