[compiler][repro] False positives for ValidatePreserveMemo #30629
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| * of its scope (but after its mutable range ends). | ||
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| function useFoo(a, b) { |
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This is the only false positive not fixed by #30630 and unrelated to #30603. Included since it shows a use-case for an identifier's original mutable range (instead of the currently used scope range).
Currently, forget (incorrectly) infers that x is potentially mutated after StartMemoize deps=[x, ...]
| useIdentity(2); | ||
| mutate(x); | ||
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| return useCallback(() => [x, []], [x]); |
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This is a false positive because the input wasn't memoized in source, right? Just making sure i'm interpreting this the same way you are.
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Yep exactly! I added this fixture to show changes from #30630
| * We currently bail out because `a` has a scope and is not transitively memoized | ||
| * (as its scope is pruned due to a hook call) |
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Interesting - looks like we are grouping the argument destructuring into a scope? that seems wrong, a and b aren't mutable so they shouldn't be getting added into any scopes.
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My understanding is that this is because x is a context variable, and since our understanding of mutable context variables is imprecise, x and all potential aliases get marked as mutable. I might be incorrect though -- can look into this more
Stack from ghstack (oldest at bottom):
Found when syncing changes from #30603 to meta codebase, see fixture comments for explanations