STL Status Chart

Explanation

This tracks the progress of the microsoft/STL repo. For more info, read the Changelog.

This chart is interactive! Click the legend to show/hide lines.

This chart has two vertical axes. For all lines, fewer is better.

Right axis:
- 0 C++17 STL features remaining to be implemented. This reached zero when we implemented <charconv>, C++17's final boss.
- C++20 STL features remaining to be implemented. This increased whenever more features were voted into the Working Paper at WG21 meetings.
- C++23 STL features remaining to be implemented. Also increases after WG21 meetings.
- LWG issue resolutions remaining to be implemented. Also increases after WG21 meetings.
- Open pull requests.
- Code review videos that have been recorded but not yet transcribed and uploaded.
Left axis:
- Active "old bugs" in our Microsoft-internal database. We're keeping them active while porting them to GitHub, unless they're discovered to be duplicates or already fixed.
- Open GitHub bugs. That is, only GitHub issues that have bug labels.
- Open GitHub issues. That is, all GitHub issues including bug, performance, throughput, etc. and excluding only cxx20, cxx23, and LWG to avoid double-counting.
- Skipped/failing tests in the libcxx test suite. There are many reasons for such tests: STL bugs, test bugs, compiler bugs, missing STL features, missing compiler features, etc. To avoid double-counting, this line excludes missing STL features.

We don't count "patch papers" as extra work when one paper adds a feature and another paper modifies that feature before we've implemented it.

This chart weights features equally, instead of weighting by usefulness for users or difficulty for implementers.

Left axis:
- The average age of open pull requests, in days.
- The average "waiting time" of open pull requests, in days. This measures how long it's been since a maintainer submitted a review requesting changes. Any other activity doesn't reset this clock.
Right axis:
- The combined age of open pull requests. The unit is PR-months (like kilowatt-hours); for example, 5 PRs that were all opened 2 months ago have a combined age of 10 PR-months.
- The combined "waiting time" of open pull requests, in PR-months.

For this chart, more is better. It includes merges into any branch and excludes PRs that were closed without being merged, which are rare.

Line: How many PRs have been merged over the past month. This uses a "30 day" sliding window, with some smoothing:
- PRs merged 0 to 20 days ago are weighted at 100%.
- PRs merged 20 to 40 days ago are weighted from 100% to 0%.
Bars: How many PRs were merged in each calendar month.