Always use appropriate preprocessor directives to guard platform-specific, version-dependent, or feature-specific code. Ensure that conditional compilation checks accurately reflect the actual availability of features and APIs, not just version numbers or single configuration flags. When gating functionality: - Use specific feature flags rather than generic version checks when possible - Combine multiple conditions when a feature depends on both version AND configuration state - Provide alternative implementations or graceful degradation for unsupported platforms - Maintain consistency in feature flag naming and usage across the codebase Example of proper conditional compilation: ```c #ifdef TREE_SITTER_FEATURE_WASM // WASM-specific code that requires __builtin_wasm_memory_size #endif #if PY_MINOR_VERSION >= 13 && !defined(Py_GIL_DISABLED) {Py_mod_gil, Py_MOD_GIL_NOT_USED}, #endif #elif !defined(__wasi__) // Platform-specific implementation #else // WASI fallback or noop implementation #endif ``` This prevents compilation errors across different environments and ensures code portability while maintaining feature availability where supported.