Implement the smallest correct change

Time: About 150 minutes: 25 reading, 95 lab, 20 testing, 10 notes.
Prerequisites: Day 25: Capture the regression first

Toolchain: current-main build

Use build/bin/clang++ and build/bin/llvm-lit from your llvm-main checkout, not whichever clang++ is first on PATH. Reproduce upstream behavior on current main and record the commit SHA. Setup guide

Learn

Local reasoning, existing conventions and narrow scope.

Read Reading

R15 · LLVM coding standards + Your llvm-project checkout
Relevant conventions; the neighboring implementation · 25 min

Reading budgets cover selected sections, not whole chapters. Link to the book; this site does not reproduce it.

Build Build or investigate

Implement your proposed fix, rebuild the affected compiler target, and run the new test.
Recheck the boundary cases.
Keep unrelated cleanups out of the diff.
If correctness remains uncertain, preserve the reproducer and investigation rather than forcing a patch.

Done when

A locally passing fix with an explanation for each changed condition, or a useful investigation ready to share.

Recall question

Why is this the right layer to fix the problem?

Completion checks

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Notes

Saved only in this browser. Keep it short enough to finish in ten minutes; none of the prompts are required. All notes, export and import