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Niels Lohmann
70380a8de6
calc_bson_sizes() and write_bson_document() are a hand-synchronized pair of passes over the same object/array tree, introduced by #5553: the size pass appends to nested_sizes in visiting order, and the write pass consumes the table by position with nested_sizes[next_size++]. Nothing checked that the write pass consumed the whole table. If a future change touched only one of the two passes - for example to skip or reject an entry - every later size prefix in the document would be silently wrong. Add JSON_ASSERT(next_size == nested_sizes.size()) where write_bson_document() returns, so such a future drift between the two passes is caught immediately (JSON_ASSERT expands to nothing in release builds using assert(), and the fuzzers/tests already build with it enabled). The two passes agree today, so this changes nothing observable; it only guards against the risk described in #5710 item 5. Extracting a shared stepper for the two passes (the second half of the proposed change) is left for a follow-up: it only saves ~30 lines and the issue asks for it only if the result reads clearly, which needs more room to get right than a mechanical cleanup pass allows. #5710 item 5 Signed-off-by: Niels Lohmann <mail@nlohmann.me>