# CORE → PROTO — `tests/conformance/cpp/CMakeLists.txt` should link `veloxproto` now

Status: **open**. Small, mechanical. Filed rather than fixed because `tests/conformance/`
is PROTO's lane.

## What's stale

`tests/conformance/cpp/CMakeLists.txt` says in its header comment:

> Links libveloxproto (the generated protocol code in core/generated/), not libveloxcore

…but it actually **compiles `core/generated/velox_proto.cpp` straight into the
executable** and finds `nlohmann_json` itself:

```cmake
add_executable(velox_conformance_cpp
    conformance_main.cpp
    ${CMAKE_SOURCE_DIR}/core/generated/velox_proto.cpp)

target_include_directories(velox_conformance_cpp PRIVATE
    ${CMAKE_SOURCE_DIR}/core/generated
    ${CMAKE_CURRENT_SOURCE_DIR})
target_link_libraries(velox_conformance_cpp PRIVATE nlohmann_json::nlohmann_json)
```

That was the only option while ADR 0009's `libveloxproto` target didn't exist. **It exists
now** — `core/CMakeLists.txt` defines `veloxproto` / `velox::proto` (commit adding it on
`lane/core`), with `core/generated/` as a `PUBLIC` include dir and `nlohmann_json` linked
`PUBLIC`. The comment and the code now agree only if the runner links the target.

## Requested change

```cmake
if(TARGET velox::proto)
    add_executable(velox_conformance_cpp conformance_main.cpp)
    target_link_libraries(velox_conformance_cpp PRIVATE velox::proto)
else()
    # Standalone configure of tests/conformance/ (no core/ in the tree): fall back to
    # compiling the generated source directly, as today.
    if(NOT TARGET nlohmann_json::nlohmann_json)
        find_package(nlohmann_json 3.11 REQUIRED)
    endif()
    add_executable(velox_conformance_cpp
        conformance_main.cpp
        ${CMAKE_SOURCE_DIR}/core/generated/velox_proto.cpp)
    target_include_directories(velox_conformance_cpp PRIVATE
        ${CMAKE_SOURCE_DIR}/core/generated)
    target_link_libraries(velox_conformance_cpp PRIVATE nlohmann_json::nlohmann_json)
endif()

target_include_directories(velox_conformance_cpp PRIVATE ${CMAKE_CURRENT_SOURCE_DIR})
target_compile_features(velox_conformance_cpp PRIVATE cxx_std_23)
add_test(NAME conformance_cpp COMMAND velox_conformance_cpp ${CMAKE_SOURCE_DIR})
set_tests_properties(conformance_cpp PROPERTIES LABELS "conformance")
```

The `if(TARGET ...)` branch keeps the suite configurable on its own (the property the
current comment says it wants) while using the real library in the normal full-tree build.
The root CMake already `add_subdirectory(core)`s before `tests/conformance`, so the target
is present in that path.

## Why it matters beyond tidiness

GUI is blocked on `libveloxproto` being a real link target (it can't `add_subdirectory` a
sibling lane's `core/generated/` and re-guess the nlohmann find). Once GUI links
`velox::proto`, the conformance runner linking the *same* target is what guarantees the
GUI and the conformance suite are exercising byte-identical generated code — compiling the
`.cpp` twice into two executables with two different warning/flag sets is exactly the kind
of skew a conformance suite exists to catch.