Table lookup collision lint and safe table indexing#2252
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These files are regenerated every time das2rst runs and don't need to be tracked. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
- Add table_lookup_collision (40216) lint error detecting multiple lookups of the same table in a single expression (tab[a] = tab[b], fun(tab[a], tab[b]), etc.) - Add ExprAt::underDeref flag set by ExprRef2Value to mark value lookups as safe (no collision risk when result is copied out) - Change unsafe_table_lookup default to false. Single tab[key] is now safe; the linter catches the actually dangerous patterns - Fix crash when global variable init contains a table lookup (push/pop collision set in preVisitGlobalLetInit/visitGlobalLetInit) - Update language docs (tables.rst, unsafe.rst, options.rst) and generated stdlib docs (ExprAtFlags, CodeOfPolicies) - Add expect test: failed_table_lookup_collision.das (6 collision cases + 3 safe cases) Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Exercises the push/pop fix in preVisitGlobalLetInit that prevented a crash when table lookups appeared in global variable initializers. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
The gitignore rule excludes generated RST files but the directory itself must exist for das2rst to write into it. Add .gitkeep so CI checkout has the directory. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
This reverts commit 697b722.
The write_to_detail macro handler runs during compilation, before das2rst main creates the directory. With detail/ gitignored, CI checkout has no directory to write into. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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Summary
table_lookup_collision(40216) lint error that detects multiple lookups of the same table in a single expression (tab[a] = tab[b],fun(tab[a], tab[b]), etc.) — these cause undefined behavior because table insertion can rehash and invalidate referencesExprAt::underDerefflag, set byExprRef2Value, to mark value lookups as safe (no collision risk when the result is immediately copied out)unsafe_table_lookupdefault tofalse— singletab[key]is now safe; the linter catches the actually dangerous multi-lookup patternspreVisitGlobalLetInit/visitGlobalLetInit)doc/source/stdlib/detail/(generated by das2rst, no need to track)Test plan
failed_table_lookup_collision.das— 6 collision cases (copy, clone, move, field access, swap, function call) + 3 safe cases (different tables, value lookups, separate expressions)tests/language/suite to verify no regressions🤖 Generated with Claude Code