Fix stack overflow compiling/validating oneOf with many variants - #2644
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momomuchu wants to merge 1 commit into
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Fix stack overflow compiling/validating oneOf with many variants#2644momomuchu wants to merge 1 commit into
momomuchu wants to merge 1 commit into
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Emit a flat sequence of if blocks instead of an O(N)-deep nested else chain, which overflowed the call stack when compiling and running large oneOf arrays (ajv-validator#2641). Only merge evaluated properties for the first matching variant so a later, conflict-causing match does not swallow a legitimate unevaluatedProperties error, matching the stock nested-else behaviour. Raise the timeout on the large-array tests.
johnconstant99-dev
approved these changes
Jul 7, 2026
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fixes #2641
oneOf emitted one nested if/else per variant, so both codegen rendering
(If.render) and the generated validator recursed O(N) deep. That threw
RangeError for oneOf arrays with ~2000+ variants (compile crashes past ~3000).
This flattens the emitted code to one if per variant at the same nesting level
instead of nesting each variant inside the previous one's else. valid/passing
track "exactly one matched so far" the same way as before, and mergeEvaluated
still runs only on the first match, so error output (passingSchemas,
unevaluatedProperties) and short-circuit behavior are unchanged. Ran the full
oneOf test file plus the JSON-Schema-Test-Suite, all green, with byte-identical
generated error objects vs current master across draft-07/2019-09/2020-12.
Left the generic If.render recursion (the codegen-level fix the issue also
suggests) out of scope here since it touches every keyword's codegen, not just
oneOf. Happy to look at that separately if useful.