microsoft / microsoft/STL

STL: Replace `_Compressed_pair` with `[[no_unique_address]]`

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#197 3 comments 0 reactions 0 assignees View on GitHub

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enhancement vNext
Dominant language
C++
Stars
11.2k
Forks
1.7k
Avg merge
4d 15h
Merged PRs (30d)
22

Description

When we can break ABI, we should replace our _Compressed_pair machinery with [[no_unique_address]] (with compiler support for downlevel usage in older Standard modes, of course). This will simplify our code, improve compiler throughput, and significantly improve debug codegen.

vNext note: Resolving this issue will require breaking binary compatibility. We won't be able to accept pull requests for this issue until the vNext branch is available. See #169 for more information.

Contributor guide

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First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

The issue names _Compressed_pair and [[no_unique_address]] but provides no file or test entry point. Wait for the vNext branch described in #169, then trace the _Compressed_pair machinery and verify that its replacement is complete while accepting the stated ABI break.

Written by the indexing model from the issue text.

Assessment

Tech stack
cpp
Domain
backend, performance
Issue type
Refactor
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
25/100

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