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fix(health): suppress defer_in_loop when the next statement exits the loop - #2942
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RaghavChamadiya merged 1 commit intoOct 3, 2026
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… loop A defer immediately followed by a return, or by a break that exits the for loop (not a switch/select case, and not only an inner loop of a nest), is reached at most once per entry, so the deferred call cannot pile up per iteration. Unlabeled break resolution walks to the innermost breakable statement; a labeled break counts only when the label names a for statement with no further loop above it up to the function scope. Everything else - a call between the defer and the exit, continue, switch/select-case breaks, labels naming inner statements, nested-loop breaks - keeps firing, and the existing fixture count is unchanged. Closes repowise-dev#2938
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Thanks @Pushpak731, this is careful work. Requiring the exit to leave the outermost loop is the part that makes it right: in for { for { defer f(); break } } the outer iteration re-enters and registers the defer again, and the test file pins that along with the func-literal return and labelled break cases. Merging.
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Summary
loop_stmt_markerreturnsNonefor adefer_statementwhose next statement in the same block is areturn, or abreakthat exits the loop: such a defer can only be reached once per entry, so the deferred call cannot pile up per iteration (Godeferthat runs once because the loop exits right after it is reported as defer in a loop #2938's hugotransform.goshape).breakresolves to the innermost breakable statement and only counts when that is theforAND no further loop wraps it up to the function scope (otherwise each outer iteration re-enters and registers the defer again). A labeledbreakcounts only when the label names aforstatement, again with no loop above it.switch/select-case breaks, labels naming inner statements,continue, and any other statement between the defer and the exit keep firing. Kept to the syntactic next-statement form per the issue; comments and the;separator of single-line bodies are skipped.deferInLoopkeeps its count of 1.Related Issues
Closes #2938
Test Plan
pytest)ruff check .)New
tests/unit/health/test_perf_go_defer_exit.py: 33 tests covering all four loop forms, bare/value/multi-value returns, the hugoif { defer; break }shape, comment and;skipping, labeled breaks naming the loop vs. naming an inner switch/if, labeled break out of a nested loop, switch/select/type-switch case breaks, inner-loop-only breaks in a nest,continue,goto, break-before-defer, per-defer coverage in one body, and the five repro shapes from the issue.tests/unit/health/in full: 2858 passed, 1 skipped;ruff checkclean.Checklist