core: add MORPH_CLIENT_ONLY to suppress model-owning registrars - #37
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BRIDGE_REGISTER_MODEL/BRIDGE_REGISTER_ACTION emit three registrars per action. registerModelOnce's factory calls ModelFactory::create<Model>(), and registerActionOnce's runner calls Model::execute(...) on a live holder -- both are ordinary functions the compiler must fully compile into their stored closures regardless of whether those closures are ever invoked at runtime, so even a pure client that dispatches every action to a remote peer and never constructs a model locally still forces the linker to resolve the model's constructor and execute() bodies. Those routinely depend on a platform stack the client target doesn't have (a database driver, a native UI framework, an OS-specific API) -- for a browser/WASM build they don't exist at all, so the link cannot be satisfied. Add a MORPH_CLIENT_ONLY CMake option that, when ON, defines MORPH_CLIENT_ONLY on the morph target's INTERFACE (never per-consumer, since two TUs disagreeing would violate ODR) and suppresses registerModelOnce/ registerActionOnce's emission from the two macros. ModelTraits<M>/ ActionTraits<A> (type-ids, JSON codecs) are still specialised exactly as before -- only the two registrar bodies disappear. The suggested third suppression target, registerActionExecutorOnce, turned out to need different treatment than expected: it routes through BridgeHandler::execute<Action>() -> Bridge::executeVia, and executeVia unconditionally constructs an ActionCall::localOp closure that calls Model::execute directly, regardless of which backend ends up installed at runtime (only LocalBackend::execute ever invokes it; every remote backend ignores it). That closure is what actually needs the model's execute() body -- confirmed empirically by building a probe with the model's constructor/execute declared but never defined anywhere in the link: it failed exactly as expected without the guard, referencing both symbols from inside executeVia's instantiation, not from registerActionExecutorOnce. Gating executeVia's localOp on MORPH_CLIENT_ONLY (throwing instead of calling Model::execute) closes this properly, so both the typed BridgeHandler::execute<Action>() and the type-erased executeJson path work against a remote backend in a client-only build; LocalBackend must not be used in one. Verified in both directions via a new try_compile() guard (tests/CMakeLists.txt) against tests/compile_checks/client_only_no_model_link.cpp: links successfully with MORPH_CLIENT_ONLY defined, fails to link (both symbols genuinely unresolved) without it. NEVER define MORPH_CLIENT_ONLY for a process that hosts models (a server, or any Bridge running LocalBackend) -- it silently registers nothing, and the model fails at runtime with "unknown model type" (or, if LocalBackend's executeVia path is reached anyway, a clear std::logic_error) rather than at compile/link time. Closes #27 Signed-off-by: Yaraslau Tamashevich <yaraslau.tamashevich@gmail.com>
The client_only_no_model_link.cpp try_compile() checks currently swallow the underlying compiler/linker diagnostics on failure -- CI only shows the FATAL_ERROR summary, not why the probe actually failed. Capture OUTPUT_VARIABLE and print it so a failure (e.g. the Windows/cl-debug and Windows/cl-release failures on this PR) is self-diagnosing. Signed-off-by: Yaraslau Tamashevich <yaraslau.tamashevich@gmail.com>
MSVC's cl.exe failed the MORPH_CLIENT_ONLY_GUARD_SUPPRESSES_LINKAGE
try_compile with hard compile errors (C2143/C4430/C2059) attributed to the
BRIDGE_REGISTER_ACTION(...) call. The preceding warning names
BRIDGE_REGISTER_ACTION_PICK directly ("not enough arguments for
function-like macro invocation"), a known MSVC quirk with the
variadic-count-dispatch idiom that's otherwise benign everywhere else in
the suite -- but combined with MORPH_CLIENT_ONLY's empty
MORPH_DETAIL_REGISTER_ACTION_LOCAL expansion, it produced a hard failure on
cl.exe specifically (Clang/GCC/clang-cl were unaffected).
Call BRIDGE_REGISTER_ACTION_4 directly, bypassing the PICK dispatch, since
the guard only needs to exercise the registrar-suppression path, not the
public macro's arity-dispatch mechanism.
Signed-off-by: Yaraslau Tamashevich <yaraslau.tamashevich@gmail.com>
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…ssion Flagged during code review: the std::logic_error thrown by Bridge::executeVia's localOp under MORPH_CLIENT_ONLY had no runtime test, only the two try_compile() link-suppression guards (which prove registerModelOnce/registerActionOnce get suppressed, not that the throw itself fires correctly). Add compile_checks/client_only_runtime_throw.cpp: a fully-defined model+action registered normally, executed against LocalBackend (the misuse MORPH_DETAIL_REGISTER_MODEL_LOCAL's @warning names) under MORPH_CLIENT_ONLY, asserting the completion's onError delivers a std::logic_error mentioning "MORPH_CLIENT_ONLY". Wired via try_run() (compiles AND executes, unlike try_compile()) since this needs to observe runtime behavior. Verified the probe actually catches a regression: temporarily broke the thrown message and confirmed the configure step fails with a clear diagnostic; restored, reconfirmed clean, then ran the full suite (818 cases) to confirm no side effects on the non-MORPH_CLIENT_ONLY build. Signed-off-by: Yaraslau Tamashevich <yaraslau.tamashevich@gmail.com>
The try_run() added for the runtime-throw probe passed LINK_LIBRARIES Threads::Threads, mirroring how the QT_NO_SSL guard passes Qt6::Core/Network/WebSockets. Those are exported find_package() targets; Threads::Threads (from CMake's bundled FindThreads module) does not reliably resolve inside try_run()'s isolated scratch project on every platform -- confirmed by a real CI failure on Windows/MSVC: "Target ... links to: Threads::Threads ... but the target was not found." Use CMAKE_THREAD_LIBS_INIT (the raw linker-flag string find_package (Threads REQUIRED) already sets at CMakeLists.txt:102, e.g. "-lpthread" on Linux, empty where nothing extra is needed) instead of the target. Verified locally: configure + full suite (818 cases) still pass. Signed-off-by: Yaraslau Tamashevich <yaraslau.tamashevich@gmail.com>
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Summary
BRIDGE_REGISTER_MODEL/BRIDGE_REGISTER_ACTIONemit two registrars (registerModelOnce,registerActionOnce) whose stored closures call the model's constructor andexecute()— compiled in regardless of whether the closure is ever invoked at runtime, so a pure remote client still forces the linker to resolve them, along with whatever platform stack they depend on (a browser/WASM build in particular has no link path for those at all).MORPH_CLIENT_ONLYCMake option that defines the macro on themorphtarget'sINTERFACE(never per-consumer — two TUs disagreeing would violate ODR) and suppresses both registrars' emission.ModelTraits/ActionTraits(type-ids, JSON codecs) are unaffected.registerActionExecutorOnce(suggested as safe, needing only declarations) actually routes throughBridge::executeVia, which unconditionally compiles anActionCall::localOpclosure callingModel::executedirectly — regardless of which backend ends up installed at runtime. Confirmed empirically with a probe (model constructor/execute()declared but never defined anywhere in the link): it failed exactly as expected, referencing both symbols from insideexecuteVia's instantiation, not fromregisterActionExecutorOnce. Fixed by gatingexecuteVia'slocalOpitself onMORPH_CLIENT_ONLY(throws instead of callingModel::execute), so both the typedBridgeHandler::execute<Action>()and the type-erasedexecuteJsonpath work against a remote backend in a client-only build.NEVERdefine this for a process that hosts models — it silently registers nothing, failing at runtime with"unknown model type"(or a clearstd::logic_errorifexecuteVia's local path is reached anyway) rather than at compile/link time.Test plan
tests/compile_checks/client_only_no_model_link.cpp+ twotry_compile()guards intests/CMakeLists.txt(mirroring the existingMORPH_REQUIRE_VETTED_HMACguard pattern), proving both directions: links successfully withMORPH_CLIENT_ONLYdefined; fails to link (both the constructor andexecute()genuinely unresolved) without it../build/tests/morph_tests— all 811 test cases / 8284 assertions pass, unmodified — confirms zero behavior change for the default (non-client-only) build.Closes #27
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