Respect the solve polarity for conditions that don't mention the var - #9345
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solve_for_{inner,outer}_interval track whether they're solving for the region
where the condition is true or where it's false, in SolveForInterval::target,
which visit(const Not *) flips. The early-out for conditions that don't mention
the variable being solved for didn't consult it, so under a negation it
returned the two answers the wrong way round.
That inverts the safe direction. Solving
!(((y % 2) != 1) && ((y % 2) != 0))
for x gives an empty outer interval, claiming the condition is nowhere true,
when it's a tautology. Written the other way round as
((y % 2) == 0) || ((y % 2) == 1)
there's no Not to flip the polarity, and it correctly gives everything.
An empty outer interval is not merely imprecise. TrimNoOps asks for the outer
interval of the condition under which a loop body does something, and deletes
the loop when that comes back empty.
The rest of the class already handles this: fail() widens to everything for an
outer bound and narrows to nothing for an inner one.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
5 tasks
Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## main #9345 +/- ##
==========================================
+ Coverage 70.01% 70.05% +0.04%
==========================================
Files 258 258
Lines 78699 78699
Branches 19160 19164 +4
==========================================
+ Hits 55100 55132 +32
+ Misses 17881 17872 -9
+ Partials 5718 5695 -23 ☔ View full report in Codecov by Harness. 🚀 New features to boost your workflow:
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alexreinking
approved these changes
Aug 15, 2026
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solve_for_{inner,outer}_interval track whether they're solving for the region where the condition is true or where it's false, in SolveForInterval::target, which visit(const Not *) flips. The early-out for conditions that don't mention the variable being solved for didn't consult it, so under a negation it returned the two answers the wrong way round.
That inverts the safe direction. Solving
!(((y % 2) != 1) && ((y % 2) != 0))
for x gives an empty outer interval, claiming the condition is nowhere true, when it's a tautology. Written the other way round as
((y % 2) == 0) || ((y % 2) == 1)
there's no Not to flip the polarity, and it correctly gives everything.