Compiling this with -cl-std=CL2.0 -inline-entry-points:

const int data = 42;
kernel void foo() {}

produces SPIR-V that fails to validate:

error: line 22: StorageBuffer OpVariable <id> '11[%11]' has illegal type.
From Vulkan spec, section 14.5.2:
Variables identified with the StorageBuffer storage class are used to access transparent buffer backed resources. Such variables must be typed as OpTypeStruct, or an array of this type
  %11 = OpVariable %_ptr_StorageBuffer_uint StorageBuffer %uint_42

Program-scope variables default to the global address space in OpenCL 2.x. Marking the variable as either static or constant fixes it.