Describe the bug, including details regarding any error messages, version, and platform.

#38027 added Buffer::span_as and Buffer::mutable_span_as

mutable_span_as has a const qualifier,

but this prevents the call to mutable_data_as during compile:

...include/arrow/buffer.h:273:41: error: passing ‘const arrow::Buffer’ as ‘this’ argument discards qualifiers [-fpermissive]
  273 |     return util::span(mutable_data_as<T>(), static_cast<size_t>(size() / sizeof(T)));

By contrast, both span_as and data_as have const qualifiers.

Also, mutable_span_as should not have a const qualifier as it implies modification of arrow::Buffer.

Component(s)

C++