Problem

Build error for T = double:

/home/vpcuser/velox/./velox/experimental/cudf/expression/AstUtils.h: In function ‘std::unique_ptr<cudf::scalar> facebook::velox::cudf_velox::makeScalarFromValue(const facebook::velox::TypePtr&, T, bool, std::optional<cudf::type_id>) [with T = double]’:
/home/vpcuser/velox/./velox/experimental/cudf/expression/AstUtils.h:79:41: error: call to ‘cudf::get_default_stream’ declared with attribute error: cudf default stream argument used. Pass stream explicitly.
   79 |   auto stream = cudf::get_default_stream();
      |                 ~~~~~~~~~~~~~~~~~~~~~~~~^~
/home/vpcuser/velox/./velox/experimental/cudf/expression/AstUtils.h:80:8: error: call to ‘cudf::get_current_device_resource_ref’ declared with attribute error: cudf default memory resource argument used. Pass mr explicitly.
   80 |   auto mr = cudf::get_current_device_resource_ref();

makeScalarFromValue() in AstUtils.h calls cudf::get_default_stream() and cudf::get_current_device_resource_ref(). When any .cpp file includes both CudfNoDefaults.h and AstUtils.h (e.g. CudfHashJoin.cpp), these calls hit the __attribute__((error)) redeclarations that guard against accidental default argument usage.

In Release builds (-O2), GCC's dead-code elimination removes unused template instantiations before the error fires. In Debug builds (-O0), all instantiations are preserved, triggering a hard compile error.

Solution

Replaces the two calls with existing approved alternatives:

• cudf::get_default_stream() → cudf::get_default_stream(cudf::allow_default_stream) (from CudfDefaultStreamOverload.h)
• cudf::get_current_device_resource_ref() → rmm::mr::get_current_device_resource() (direct RMM call, same pattern as get_temp_mr() in CudfNoDefaults.h)

Both return identical values at runtime — zero performance impact.

Changes

• velox/experimental/cudf/expression/AstUtils.h: Update makeScalarFromValue() to use poison-safe alternatives