Fix cutlass inductor options for PyTorch < 2.8.0 (#3988)

The cuda.cutlass_epilogue_fusion_enabled and cuda.cutlass_tma_only
inductor config options were added in PyTorch 2.8.0. Using these
options on older PyTorch versions causes a RuntimeError during
GRPOTrainer initialization.

This fix adds a version check to only include these options when
running PyTorch 2.8.0 or later, allowing GRPO training to work on
older PyTorch versions (e.g., Colab environments with PyTorch 2.5-2.7).

Co-authored-by: Daniel Hanchen <danielhanchen@users.noreply.github.com>

unsloth/models/rl.py

@@ -70,6 +70,12 @@ except Exception:
     except Exception:
         trl_version = Version("0.0.0")
 
+# Get PyTorch version for feature detection
+try:
+    torch_version = Version(torch.__version__.split("+")[0].split("a")[0].split("b")[0])
+except Exception:
+    torch_version = Version("0.0.0")
+
 
 def vLLMSamplingParams(**kwargs):
     from vllm import SamplingParams
@@ -1126,16 +1132,18 @@ def _patch_trl_rl_trainers(trainer_file = "grpo_trainer"):
         # Generate torch_compile_options based on device type
         if DEVICE_TYPE == "cuda":
             # CUDA-specific options (added to base options)
-            new_options = (
-                base_options
-                + """
-            "triton.enable_persistent_tma_matmul": torch.cuda.get_device_capability()[0] >= 9,
+            cuda_options = """
+            "triton.enable_persistent_tma_matmul": torch.cuda.get_device_capability()[0] >= 9,"""
+            # cutlass options were added in PyTorch 2.8.0
+            if torch_version >= Version("2.8.0"):
+                cuda_options += """
             "cuda.cutlass_epilogue_fusion_enabled": torch.cuda.get_device_capability()[0] >= 9,
-            "cuda.cutlass_tma_only": torch.cuda.get_device_capability()[0] >= 9,
+            "cuda.cutlass_tma_only": torch.cuda.get_device_capability()[0] >= 9,"""
+            cuda_options += """
             "cuda.compile_opt_level"              : "-O2",
             "cuda.enable_cuda_lto"                : True,
         }"""
-            )
+            new_options = base_options + cuda_options
         else:
             # XPU, HIP, and other device types use base options only
             new_options = (