A virtual call through an out-of-line definition is classified as a direct call

Index: Known gaps

Status (2026-10-25): FIXED. Originally reported 2026-10-21: call_graph.py's _ref_is_virtual decides whether a member call is virtual from the resolved callee declaration node. Clang's referencedMemberDecl for a call to a method defined out of line (double Shape::area() const { ... } in a .cpp) points at the definition, which carries no virtual flag. The call is then recorded as call_kind: direct, resolution: exact, so virtual_dispatch_graph.py never materializes its VIRTUAL_CALL_MAY_DISPATCH_TO edges and PUBLIC_VIRTUAL_DISPATCH_SET_CHANGED cannot fire for that base.

Reproduced with the real producer (fold_semantic_graphs over clang 18): the same call on a method defined in-class yields call_kind: virtual and a VIRTUAL_CALL_MAY_DISPATCH_TO edge; the out-of-line variant yields direct and none.

false-clean — The call reads as a direct, exact call to a method whose targets can in fact change. The dispatch-set detector stays silent rather than reporting a change it cannot see.

Fix (2026-10-25): _ref_is_virtual walks the previousDecl chain through member_index (cycle-guarded; previousDecl added to call_decl_record._MEMBER_INDEX_FIELDS). Every out-of-line virtual call in a stored call graph changes call_kind, so EXTRACTOR_GENERATION advanced to 24 (header graph) and SOURCE_GENERATION to 10 (L5); an older graph is reported as generation drift. Pinned by tests/test_call_graph_out_of_line_virtual.py (hand-built shapes plus six real-clang sibling shapes and an end-to-end L5 dispatch join). Residual: an override redeclared with neither virtual nor override/final is still read as direct (the pre-existing, documented _ref_is_virtual false negative).

Original fix direction: the definition node carries previousDecl back to the in-class declaration, which does carry virtual. _ref_is_virtual should follow previousDecl before deciding. This changes the call_kind of every out-of-line virtual call in every call graph, so it has its own compatibility analysis and tests and was not folded into the detector PR. Owner: buildsource/call_graph.py.