[Dikluwe]

Problem

SoBase::removeAuditor(auditor, type) currently ignores type. When a pointer has registrations with different types, removal can delete the wrong registration. Tree rotations also mean equal keys can appear on either side, so a pointer/data search must inspect both equal-key subtrees.

Changes

• Add the C API cc_rbptree_remove_with_data(), removing one matching occurrence without changing the tree when the pair is absent.
• Use the same total pointer ordering as insertion when searching for the pair.
• Pass the registration type from SoBase::removeAuditor().
• Exercise typed removal from SoBase and a real C client, including duplicate pairs, missing pairs, null data and inline/allocated nodes.

Both key and data may be null and remain borrowed. Existing signatures/layout are preserved; the added C symbol is exported. The C client is compiled as C and linked with the C++ driver so the instrumented Coin library can resolve its vptr runtime. The final comment-only commit restores documentation to the public removal function.

Dependencies — keep as draft

Requires the SoBase cache PR #821 and #813. This branch includes both prerequisites, so its current diff against master is cumulative. Rebase after the prerequisites are integrated before marking ready.

Validation

Linux candidate 90/90 CTests, individual integration lab 134/134. The C symbol was linked and checked with nm. A diagnostic implementation that ignored type failed the regression. Nullable C clients passed ASan/UBSan/LeakSanitizer. The final publication integration gate is recorded below; the comment-only refinement preserves executable source tokens.

Final publication gate — 2026-10-08

The exact published heads, merged over the existing integration lab, passed 13/13 directed CTests and 139/139 total CTests, with no skips. GCC/Ninja Debug shared build, COIN_THREADSAFE=ON, external Expat, all build/compiler temporary files in RAM. The GLX test environment used Xvfb, LIBGL_ALWAYS_SOFTWARE=1 and COIN_GLX_PIXMAP_DIRECT_RENDERING=1. The initial full run omitted the latter setting and failed to create GLX contexts; the corrected environment passed without code changes. Integration commit: bc83f34.

Native Windows/macOS and ABI checks are left to this PR's CI.

Typed-removal delta after the cache prerequisite (this comparison also includes #813).