Fix reshape bug (support for opset version 1) (#1667)

* Make reshape op version 1

* Refactor per PR feedback

crates/burn-import/src/onnx/dim_inference.rs

@@ -194,30 +194,27 @@ fn concat_update_outputs(node: &mut Node) {
 
     node.outputs[0].ty = ArgType::Tensor(tensor.clone());
 }
-
 fn reshape_update_outputs(node: &mut Node) {
-    assert_eq!(node.inputs.len(), 2);
-
-    let shape = if let Some(Data::Int64s(ref shape)) = node.inputs[1].value {
-        shape
-    } else {
-        panic!("Reshape: int64s shape is expected per ONNX spec");
+    let shape = match node.inputs.get(1) {
+        Some(input) => match &input.value {
+            Some(Data::Int64s(shape)) => Some(shape.clone()),
+            _ => panic!("Reshape: invalid input types"),
+        },
+        None => node.attrs.get("shape").cloned().map(|v| v.into_i64s()),
     };
 
-    // The output dimension is the same as the shape length
-    let dim = shape.len();
-    let elem_type = match node.inputs[0].ty.clone() {
-        ArgType::Tensor(tensor) => tensor.elem_type,
-        _ => panic!("Reshape: invalid input type"),
+    let output = match &node.outputs[0].ty {
+        ArgType::Tensor(tensor) => tensor.clone(),
+        _ => panic!("Reshape: invalid output types"),
     };
 
-    let shape = shape.iter().map(|&dim| dim as usize).collect();
-
-    node.outputs[0].ty = ArgType::Tensor(TensorType {
-        elem_type,
-        dim,
-        shape: Some(shape),
-    });
+    if let Some(shape) = shape {
+        node.outputs[0].ty = ArgType::Tensor(TensorType {
+            dim: shape.len(),
+            shape: None, // shape is calculated at runtime
+            ..output
+        });
+    }
 }
 
 fn reduce_mean_update_outputs(node: &mut Node) {
@@ -254,40 +251,24 @@ fn reduce_mean_update_outputs(node: &mut Node) {
 
 /// Update the output tensor dimension based on the "axes" attribute or the second input
 fn unsqueeze_update_output(node: &mut Node) {
-    let axes = if node.inputs.len() == 2 {
-        // get the values while making sure the types are correct
-        match &node.inputs[1].value {
-            Some(value) => match value {
-                Data::Int64s(axes) => Some(axes.clone()),
-                _ => panic!("Unsqueeze: invalid input types"),
-            },
-            None => None,
-        }
-    } else {
-        node.attrs
-            .iter()
-            .find_map(|(key, value)| match key.as_str() {
-                "axes" => Some(value.clone().into_i64s()),
-                _ => None,
-            })
+    let axes = match node.inputs.get(1) {
+        Some(input) => match &input.value {
+            Some(Data::Int64s(axes)) => Some(axes.clone()),
+            _ => panic!("Unsqueeze: invalid input types"),
+        },
+        None => node.attrs.get("axes").cloned().map(|v| v.into_i64s()),
     };
 
-    // need output way up here to avoid borrowing issues
     let input = match &node.inputs[0].ty {
         ArgType::Tensor(tensor) => tensor.clone(),
-        _ => panic!("Unsqueeze: invalid output types"),
+        ty => panic!("Unsqueeze: invalid output type ({ty:?})"),
     };
 
-    let output = match &node.outputs[0].ty {
-        ArgType::Tensor(tensor) => tensor.clone(),
-        _ => panic!("Unsqueeze: invalid output types"),
-    };
-
-    if axes.is_some() {
+    if let Some(axes) = axes {
         node.outputs[0].ty = ArgType::Tensor(TensorType {
-            dim: input.dim + axes.unwrap().len(),
+            dim: input.dim + axes.len(),
             shape: None, // shape is calculated at runtime
-            ..output
+            ..input
         });
     }
 }