case98 — C++ standard floor raised (per-binary: NO_CHANGE)¶

Field	Value
Verdict	✅ NO_CHANGE
Category	No Change
Platforms	Linux, macOS, Windows
Flags	—
Detected `ChangeKind`s	—
Source files	`examples/case98_cxx_standard_floor_raised/`

What this case demonstrates¶

v1.h and v2.h declare an identical public surface. The difference is the build contract: v2 is compiled with -std=c++20 (via V2_COMPILE_OPTIONS in CMakeLists.txt), so the .so was produced under a higher C++ standard floor than v1. Consumers still building with C++17 see no symbol churn but a freshly compiled TU against the new headers will hit any C++20-only constructs the library starts to require.

Why per-binary detection cannot see this¶

The symbol set, vtable, and declared interface are unchanged between v1 and v2, so every conventional ABI diff returns NO_CHANGE. The break-grade signal only appears when abicheck is fed a matrix of per-configuration snapshots (one per consumer toolchain): the CXX_STANDARD_FLOOR_RAISED detector compares the minimum cxx_std across configurations and emits the finding when the floor moves up.

The probe-harness mechanism that produces matrix snapshots lives in abicheck.probe_harness; it is not yet wired into the default compare CLI (deferred follow-up — see PR #247).

Expected verdict¶

NO_CHANGE — single-config diff is correctly silent. The case is a fixture for the matrix-detector channel.

Source files¶

CMakeLists.txt
app.cpp
v1.cpp
v1.h
v2.cpp
v2.h