A labelled side-scoped --include appeared to suppress unlabelled global include roots

Index: Known gaps — closed and moot

Status (2026-11-01): CLOSED. Reproduced with castxml and fixed by #1314's additive composition rule (abicheck/model/sided_inputs.py), which the labelled form reaches too. Pinned by tests/test_sided_include_labelled_composition.py; see the archive entry for the matrix and the not-comparable boundary for asymmetric labels.

Observed once, on a real PVXS comparison, and not yet reduced to a minimal reproduction — recorded so the next person does not lose the observation. Invoking:

compare old.so new.so --include old:public=OLD_INC --include new:public=NEW_INC \
  --include EPICS_INC --include EPICS_INC/os/Linux --include EPICS_INC/compiler/gcc ...

failed with fatal error: 'epicsTime.h' file not found, despite EPICS_INC being passed as an unlabelled (both-sides) include root and genuinely containing that header. The same roots passed to a bare dump worked. Re-expressing every root in the per-side labelled form made the comparison succeed.

So either unlabelled roots are dropped once any labelled side-scoped root is given for that side, or they are ordered such that castxml does not see them. --include's own help text documents the two forms as composable, so if this reproduces it is a defect rather than a usage error. Next step: a minimal two-header fixture mixing one labelled and one unlabelled root.

Resolution (2026-11-01)

The minimal reproduction is tests/test_sided_include_labelled_composition.py: each side's public header includes sic_dep.h, which exists only in a shared root and itself includes sic_os.h from a nested shared root (the EPICS_INC / EPICS_INC/os/Linux shape). Every combination of side spelling (old=/new=, old:public=/new:public=) and shared spelling (bare, both=, both:support=), in either argument order, parses both sides and reports the header-only parameter change. Switching compose_sided_paths back to replacement makes every cell fail, which is the PVXS symptom: the observation was bug class config.sided_shared_input_dropped, fixed in #1314 for every spelling.

Labelling one side's root and not the other's is refused as not comparable (exit 16, include_sequence): a label is part of the extraction contract, so that is two contracts, not a dropped root.