Use custom exceptions rather than re-exporting them from onnx

CHANGELOG.rst

@@ -7,7 +7,14 @@
 Change log
 ==========
 
-0.9.1 (2023-xx-xx)
+0.10.0 (2023-xx-xx)
+------------------
+
+**Breaking change**
+
+- Failures during type/shape inference and model validation now use exceptions defined in ``spox`` rather than passing through exceptions from ``onnx``. This addresses an issues where the type of the exceptions raised from ``onnx`` depends on the host platform.
+
+0.9.1 (2023-10-05)
 ------------------
 
 **Bug fix**

src/spox/_exceptions.py

@@ -1,7 +1,9 @@
-import onnx.shape_inference
+class InferenceError(Exception):
+    """An error originating from the type or shape inference."""
 
-InferenceError = onnx.shape_inference.InferenceError
-ValidationError = onnx.checker.ValidationError
+
+class ValidationError(Exception):
+    """A failure to validate against the standard."""
 
 
 class InferenceWarning(Warning):

src/spox/_standard.py

@@ -137,10 +137,18 @@ def infer_output_types_onnx(self) -> Dict[str, Type]:
             typed_model = onnx.shape_inference.infer_shapes(
                 model, check_type=True, strict_mode=True, data_prop=True
             )
-        except InferenceError as e:
-            raise type(e)(
+        except onnx.shape_inference.InferenceError as e:
+            raise InferenceError(
                 f"{str(e)} -- for {self.schema.name}: {self.signature}"
             ) from e
+        except RuntimeError as e:
+            # onnx to raises a less descriptive `RuntimeError`s on MacOS out of needless cruelty
+            if "[ShapeInferenceError]" in str(e):
+                raise InferenceError(
+                    f"{str(e)} -- for {self.schema.name}: {self.signature}"
+                ) from e
+            else:
+                raise e
 
         # Recover the types from protobuf, ignoring empty protobuf objects for failing/unimplemented type inference.
         results = {