Remove CriterionTest.test_cuda code for dtype None. (#45316)

Summary:
Pull Request resolved: #45316

It's never used.

Test Plan: Imported from OSS

Reviewed By: albanD

Differential Revision: D23919449

Pulled By: gchanan

fbshipit-source-id: f9aaeeabf3940389156bfc01bc3118d348ca4cf6

Author: gchanan

torch/testing/_internal/common_nn.py

@@ -5089,7 +5089,7 @@ def apply_fn(input1, input2, target, *params):
         if self.check_gradgrad:
             gradgradcheck(apply_fn, inputs)
 
-    def test_cuda(self, test_case, dtype=None, extra_args=None):
+    def test_cuda(self, test_case, dtype, extra_args=None):
         def convert_dtype(obj, dtype, requires_grad=False):
             if isinstance(obj, torch.Tensor):
                 return obj.detach().to(dtype=dtype).requires_grad_(requires_grad)
@@ -5107,12 +5107,11 @@ def convert_dtype(obj, dtype, requires_grad=False):
         gpu_module = self.constructor(*self.constructor_args)
 
         # Convert input, target and module parameters to dtype
-        if dtype is not None:
-            cpu_input = convert_dtype(cpu_input, dtype, True)
-            if cpu_target.is_floating_point() or cpu_target.is_complex():
-                cpu_target = convert_dtype(cpu_target, dtype)
-            cpu_module.type(dtype)
-            gpu_module.type(dtype)
+        cpu_input = convert_dtype(cpu_input, dtype, True)
+        if cpu_target.is_floating_point() or cpu_target.is_complex():
+            cpu_target = convert_dtype(cpu_target, dtype)
+        cpu_module.type(dtype)
+        gpu_module.type(dtype)
 
         # GPU setup
         gpu_input = to_gpu(cpu_input)
@@ -5128,13 +5127,14 @@ def convert_dtype(obj, dtype, requires_grad=False):
 
         cpu_output = test_case._forward_criterion(cpu_module, cpu_input, cpu_target, extra_args=extra_args)
         gpu_output = test_case._forward_criterion(gpu_module, gpu_input, gpu_target, extra_args=extra_args)
-        # dtype can be None, so set precision in this way instead of a precision map
+        # dtype used to be able to be None, so set precision in this way instead of a precision map
         # TODO(#38095): Replace assertEqualIgnoreType. See issue #38095
         test_case.assertEqualIgnoreType(cpu_output, gpu_output,
                                         atol=1e-1 if dtype in {torch.half, torch.bfloat16} else 4e-4, rtol=0)
 
         cpu_gradInput = test_case._backward_criterion(cpu_module, cpu_input, cpu_target, extra_args=extra_args)
         gpu_gradInput = test_case._backward_criterion(gpu_module, gpu_input, gpu_target, extra_args=extra_args)
+        # dtype used to be able to be None, so set precision in this way instead of a precision map
         # TODO(#38095): Replace assertEqualIgnoreType. See issue #38095
         test_case.assertEqualIgnoreType(cpu_gradInput, gpu_gradInput,
                                         atol=1e-1 if dtype in {torch.half, torch.bfloat16} else 4e-4, rtol=0)