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A schema nested past 124 levels builds, then fails reading back its stored schema #172
Description
struct S {
a: u8[][][]… // 125 levels; unions nested as deep fail the same way
}
error build failed: CBOR decode failed: RecursionLimitExceeded
124 levels build; at 125 the build stores the schema, then can't decode what it stored. The failure is an internal error with no source location.
Fix: a nesting limit below the store's, checked before freezing, with a diagnostic pointing at the type. Related: the depth limit in the bounds design (core#98).
Found on core master (a8aee68).
Activity
Kinflou commentedon Nov 9, 2026
Fixed by e454cc0.
parse_schemarefuses a syntax tree deeper thanMAX_SYNTAX_DEPTH(256 levels, about 80 arrays), with a diagnostic at the node. That's below the ~124 arrays where the stored schema stopped decoding. Since #215, theids_compilefuzz target round-trips every schema it compiles through CBOR, on pull requests and nightly.