Change data() accessor in Caffe2 to return non-const pointer. (#16176)

Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/16176

This makes PyTorch and Caffe2's data() method line up.
Historically, PyTorch made no distinction between tensors
with const or non-const data, and thus provided a
non-const pointer with data() member.  Changing the API to
return a const-pointer would break all mutable code, whereas
changing the Caffe2 API to change a pointer doesn't break
any code, *except* for code which required an exact match
on const-ness (e.g., in template arguments).  Since the latter
is less disruptive, we've opted for it here.

The few places downstream that broke due to this are fixed
in this patch.

Reviewed By: smessmer

Differential Revision: D13742916

fbshipit-source-id: baa4b4544cfdf7c1f369f4d69a1e0d5953c1bd99

diff --git a/caffe2/core/tensor.h b/caffe2/core/tensor.h
index fb6c3a8..998c237 100644 (file)
--- a/caffe2/core/tensor.h
+++ b/caffe2/core/tensor.h
@@ -378,15 +378,15 @@ class CAFFE2_API Tensor final {
   }
 
   /**
-   * Returns a const raw void* pointer of the underlying storage. mutable_data()
+   * Returns a raw void* pointer of the underlying storage. mutable_data()
    * or raw_mutable_data() must have been called prior to this function call.
    */
-  inline const void* raw_data() const {
+  inline void* raw_data() const {
     return impl_->data();
   }
 
   template <typename T>
-  inline const T* data() const {
+  inline T* data() const {
     return impl_.get()->data<T>();
   }