NanoVDB: fix remaining Windows warnings-as-errors fallout

Clearing the dll-interface diagnostics unblocked the Windows projects
to compile further, exposing two more pre-existing warning classes that
NANOVDB_CUDA_WERROR now promotes to errors:

Guard the _USE_MATH_DEFINES definition in the four examples that
define it. The Windows build also passes -D_USE_MATH_DEFINES on the
command line (as 1), so the bare #define (empty) triggered MSVC C4005
macro-redefinition warnings, which the flag turns into C2220 errors.

Suppress EDG #177 for the CUDA gtest targets on Windows. gtest's TEST
macro declares each test's static test_info_ member with an
unused-attribute on GCC/Clang but not under MSVC, so for tests defined
inside an anonymous namespace (TestBuffer.cu, TestMemoryResource.cu,
TestUtilCuda.cu) the front end proves it unreferenced and reports #177
-- 76 errors, all from the macro machinery, none actionable in our
code. TestNanoVDB.cu is unaffected because its tests are declared at
namespace scope. The suppression is per-target and Windows-only, so
#177 stays enforced for all library headers, tools and examples on
every platform, and for everything on Linux.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Signed-off-by: Mark Harris <mharris@nvidia.com>

Author: harrism

nanovdb/nanovdb/examples/ex_collide_level_set/nanovdb.cu

@@ -1,7 +1,9 @@
 // Copyright Contributors to the OpenVDB Project
 // SPDX-License-Identifier: Apache-2.0
 
+#ifndef _USE_MATH_DEFINES
 #define _USE_MATH_DEFINES
+#endif
 #include <cmath>
 #include <chrono>
 

nanovdb/nanovdb/examples/ex_raytrace_fog_volume/nanovdb.cu

@@ -1,7 +1,9 @@
 // Copyright Contributors to the OpenVDB Project
 // SPDX-License-Identifier: Apache-2.0
 
+#ifndef _USE_MATH_DEFINES
 #define _USE_MATH_DEFINES
+#endif
 #include <cmath>
 #include <chrono>
 

nanovdb/nanovdb/examples/ex_raytrace_iso_surface/nanovdb.cu

@@ -1,7 +1,9 @@
 // Copyright Contributors to the OpenVDB Project
 // SPDX-License-Identifier: Apache-2.0
 
+#ifndef _USE_MATH_DEFINES
 #define _USE_MATH_DEFINES
+#endif
 #include <cmath>
 #include <chrono>
 

nanovdb/nanovdb/examples/ex_raytrace_level_set/nanovdb.cu

@@ -1,7 +1,9 @@
 // Copyright Contributors to the OpenVDB Project
 // SPDX-License-Identifier: Apache-2.0
 
+#ifndef _USE_MATH_DEFINES
 #define _USE_MATH_DEFINES
+#endif
 #include <cmath>
 #include <chrono>
 

nanovdb/nanovdb/unittest/CMakeLists.txt

@@ -79,6 +79,18 @@ if(NANOVDB_USE_CUDA)
   target_link_libraries(nanovdb_test_cuda_buffer PRIVATE nanovdb GTest::GTest GTest::Main)
   set_target_properties(nanovdb_test_cuda_buffer PROPERTIES CUDA_SEPARABLE_COMPILATION ON)
   add_test(nanovdb_cuda_buffer_unit_test nanovdb_test_cuda_buffer)
+
+  if(WIN32)
+    # gtest's TEST macro declares each test's static test_info_ member with an
+    # unused-attribute on GCC/Clang but not under MSVC, so for tests defined
+    # inside an anonymous namespace the CUDA front end can prove it
+    # unreferenced and reports #177, which NANOVDB_CUDA_WERROR promotes to an
+    # error. Suppress #177 for the CUDA test sources that use that style.
+    foreach(_cuda_gtest nanovdb_test_cuda_buffer nanovdb_test_cuda_memory_resource
+            nanovdb_test_cuda_util nanovdb_test_cuda_util_sync)
+      target_compile_options(${_cuda_gtest} PRIVATE "$<$<COMPILE_LANGUAGE:CUDA>:--diag-suppress=177>")
+    endforeach()
+  endif()
 endif()
 
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