fix: supernet_for uses mask intersection instead of common prefix#16
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fix: supernet_for uses mask intersection instead of common prefix#16
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The old algorithm only compared base addresses to find a common prefix, ignoring input masks entirely. This produced incorrect results when inputs had different prefix lengths (e.g. /24 and /16 with the same base address returned /24 instead of /16). New algorithm — intersects masks and clears bits where addresses disagree, yielding the tightest valid supernet. Unfortunately, this fix resulted in many tests broken. Several existing tests expected the old (wider) supernet values. These were not catching the bug — they simply matched the previous lossy behavior and have been updated to reflect the correct tighter results. Also fixes binary_split to fold supernet_for over all window elements instead of just the endpoints, since the tighter supernet no longer guarantees contiguous address coverage.
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The old algorithm only compared base addresses to find a common prefix, ignoring input masks entirely. This produced incorrect results when inputs had different prefix lengths (e.g. /24 and /16 with the same base address returned /24 instead of /16).
New algorithm — intersects masks and clears bits where addresses disagree, yielding the tightest valid supernet.
Unfortunately, this fix resulted in many tests broken. Several existing tests expected the old (wider) supernet values. These were not catching the bug — they simply matched the previous lossy behavior and have been updated to reflect the correct tighter results.
Also fixes binary_split to fold supernet_for over all window elements instead of just the endpoints, since the tighter supernet no longer guarantees contiguous address coverage.