[OpenCL] Test case for C++ for OpenCL 2021 in OpenCL C header test

[Topotuna]

Summary

RUN line representing C++ for OpenCL 2021 added to the test. This
should have been done as part of earlier commit fb321c2ea274 but
was missed during rebasing.

[Anastasia]

LGTM! Thanks

clang/test/Headers/opencl-c-header.cl

 // RUN: %clang_cc1 -O0 -triple spir-unknown-unknown -internal-isystem ../../lib/Headers -include opencl-c.h -emit-llvm -o - %s -verify | FileCheck %s
 // RUN: %clang_cc1 -O0 -triple spir-unknown-unknown -internal-isystem ../../lib/Headers -include opencl-c.h -emit-llvm -o - %s -verify -cl-std=CL1.1 | FileCheck %s
 // RUN: %clang_cc1 -O0 -triple spir-unknown-unknown -internal-isystem ../../lib/Headers -include opencl-c.h -emit-llvm -o - %s -verify -cl-std=CL1.2 | FileCheck %s
-// RUN: %clang_cc1 -O0 -triple spir-unknown-unknown -internal-isystem ../../lib/Headers -include opencl-c.h -emit-llvm -o - %s -verify -cl-std=clc++ | FileCheck %s --check-prefix=CHECK20
+// RUN: %clang_cc1 -O0 -triple spir-unknown-unknown -internal-isystem ../../lib/Headers -include opencl-c.h -emit-llvm -o - %s -verify -cl-std=clc++1.0 | FileCheck %s --check-prefix=CHECK20
 // RUN: %clang_cc1 -O0 -triple spir-unknown-unknown -internal-isystem ../../lib/Headers -include opencl-c.h -emit-llvm -o - %s -verify -cl-std=CL3.0 | FileCheck %s
+// RUN: %clang_cc1 -O0 -triple spir-unknown-unknown -internal-isystem ../../lib/Headers -include opencl-c.h -emit-llvm -o - %s -verify -cl-std=clc++2021 | FileCheck %s
 
 // Test including the default header as a module.
 // The module should be compiled only once and loaded from cache afterwards.
 // Change the directory mode to read only to make sure no new modules are created.
 // Check time report to make sure module is used.
 // Check that some builtins occur in the generated IR when called.
 
 // ===

 // CHECK-NOT: ndrange_t
 // CHECK20: ndrange_t
 // CHECK: _Z16convert_char_rtec
 // CHECK-NOT: _Z3ctzc
 // CHECK20: _Z3ctzc
 // CHECK20: _Z16convert_char_rtec
 char f(char x) {
 // Check functionality from OpenCL 2.0 onwards
-#if defined(__OPENCL_CPP_VERSION__) || (__OPENCL_C_VERSION__ == CL_VERSION_2_0)
+#if (__OPENCL_CPP_VERSION__ == 100) || (__OPENCL_C_VERSION__ == CL_VERSION_2_0)
   ndrange_t t;
   x = ctz(x);
 #endif //__OPENCL_C_VERSION__
   return convert_char_rte(x);
 }
 
 // Verify that a builtin using a write_only image3d_t type is available
 // from OpenCL 2.0 onwards.
 
 // CHECK20: _Z12write_imagef14ocl_image3d_wo
 #if defined(__OPENCL_CPP_VERSION__) || (__OPENCL_C_VERSION__ >= CL_VERSION_2_0)
 void test_image3dwo(write_only image3d_t img) {
   write_imagef(img, (0), (0.0f));
 }
 #endif //__OPENCL_C_VERSION__
 
 #if defined(__OPENCL_CPP_VERSION__)
 // Test old atomic overloaded with generic addr space.
 void test_atomics(__generic volatile unsigned int* a) {
   atomic_add(a, 1);
 }
 #endif
 
 // Verify that ATOMIC_VAR_INIT is defined.
-#if defined(__OPENCL_CPP_VERSION__) || (__OPENCL_C_VERSION__ == CL_VERSION_2_0)
+#if (__OPENCL_CPP_VERSION__ == 100) || (__OPENCL_C_VERSION__ == CL_VERSION_2_0)
 global atomic_int z = ATOMIC_VAR_INIT(99);
 #endif //__OPENCL_C_VERSION__
 // CHECK-MOD: Reading modules
 
 // Check that extension macros are defined correctly.
 
 // For SPIR all extensions are supported.
 #if defined(__SPIR__)