[ARROW-12530] [C++] Remove Buffer::mutable_data_ member and use const_cast on data_ only if is_mutable_ is true

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 5.0.0
• Component/s: C++
• Labels: pull-request-available
• External issue URL: https://github.com/apache/arrow/issues/28294
• Assignee: Antoine Pitrou
• Reporter: Wes McKinney
• Created: 24/Apr/21 22:03
• Updated: 11/Jan/23 08:27
• Resolved: 13/May/21 02:34

Description

Proposed new implementation of mutable_data() by apitrou

  uint8_t* mutable_data() {
     return is_mutable() ? const_cast<uint8_t*>(data()) : nullptr;
   }

This will help avoid various classes of bugs (initializing Buffer subclasses incorrectly) and make the object smaller on the heap

Issue Links

• is related to: ARROW-12495 [C++][Python] NumPy buffer sets is_mutable_ to true but does not set mutable_data_ when the NumPy array is writable
• is related to: ARROW-11172 [Python] NumPyBuffer does not set mutable_data_
• links to: GitHub Pull Request #10303