Wasm build fails: #ifndef EMSCRIPTEN guards never fire (Emscripten defines __EMSCRIPTEN__, not EMSCRIPTEN)

[rustyconover]

Summary

While building this extension as part of the DuckDB community extensions program (via the haybarn-community-extensions fork's CI, which builds every community extension across Linux/macOS/Windows/Wasm), all three Wasm targets (wasm_eh, wasm_mvp, wasm_threads) fail to compile.

Error

/duckdb_build_dir/src/quack_oauth_extension.cpp:19:10: fatal error: 'telemetry.hpp' file not found
/duckdb_build_dir/src/check_authorization_function.cpp:32:10: fatal error: 'telemetry.hpp' file not found
/duckdb_build_dir/src/diagnose.cpp:22:10: fatal error: 'telemetry.hpp' file not found
/duckdb_build_dir/src/settings.cpp:8:10: fatal error: 'telemetry.hpp' file not found

Full failing job: https://github.com/Query-farm-haybarn/haybarn-community-extensions/actions/runs/33027342386 (wasm_eh leg; wasm_mvp/wasm_threads fail identically)

Root cause

CMakeLists.txt correctly skips building posthog-telemetry (and its include path) for Wasm:

if(NOT EMSCRIPTEN)
    include_directories(posthog-telemetry/include)
    add_subdirectory(posthog-telemetry)
    ...
endif()

and each .cpp that includes "telemetry.hpp" does guard it with #ifndef EMSCRIPTEN / #endif, e.g. in src/quack_oauth_extension.cpp:

#ifndef EMSCRIPTEN
#include "acquire_function.hpp"
...
#include "telemetry.hpp"
#endif

The mismatch: if(EMSCRIPTEN) in CMakeLists.txt is a CMake-level variable (set by CMake's Emscripten toolchain file), but #ifndef EMSCRIPTEN in the .cpp files is a C preprocessor check for a macro that emcc never actually defines — Emscripten auto-defines __EMSCRIPTEN__ (double leading/trailing underscore), not bare EMSCRIPTEN. Since nothing in CMakeLists.txt does an explicit add_definitions(-DEMSCRIPTEN) / target_compile_definitions(... EMSCRIPTEN) to bridge the two, the preprocessor guard is always false on a real Wasm build, so the include always fires — right after CMake has correctly excluded the header/library it points at.

Suggested fix

Swap the preprocessor guards from #ifndef EMSCRIPTEN to #ifndef __EMSCRIPTEN__ in the affected files (quack_oauth_extension.cpp, check_authorization_function.cpp, diagnose.cpp, settings.cpp, and any others using the same pattern) — that's the macro Emscripten's compiler actually provides, and it'll make the guard do what the surrounding comments already say it's meant to do. Native (Linux/macOS/Windows) builds all pass fine today, so this is Wasm-only.

Thanks for maintaining this extension — happy to help verify a fix if useful!