The rule deciding which integer identifies a backend-minted symbol —
content-derived `disamb` for a lifted hook (`setHookDisamb`), `itemId.item`
otherwise — was written out at three sites: `mangleProcNameExt` and
`ccgutils.makeUnique` for the C name, `ast2nif.toNifSymName` for the NIF name,
each carrying its own copy of the ten-line rationale.
They drifted, which is exactly cce17461d: `toNifSymName` lacked the hook
exception, so the loader overwrote a content-derived value and two unrelated
`=destroy` hooks collided on one C name (C accepted the mistyped call, C++
rejected it). `astdef.backendMintedDisamb` is now the single definition and all
three call it. `globalName` still reads `disamb` directly — correct for a loaded
symbol, and the round-trip invariant that makes it agree is now stated in the
shared function instead of left implicit.
Pure de-duplication, verified as such: all 219 generated `.c` files of a
219-module corpus and the linked binary are byte-identical to the previous
commit. Plus 16/16 metamorphic IC tests, the 17-file `koch ic` suite, 13/13
differential edit checks against `nim c`, and the debug and release `bootic`
fixed points.
Note for the record: this started as an attempt to replace the per-process
`_c<itemId.item>` counter with a content hash. Instrumenting both mangling
sites showed that branch is never taken — 0 of 166 backend-minted manglings on
the corpus, 0 of 257 on the compiler, all going through the content-derived
path — so rewriting the scheme would have shifted every backend-minted C name
and forced an `icFormatVersion` bump for no demonstrable benefit.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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