wasm-ld: error: 'atomics' feature is disallowed (protobuf)

Hi,

I am trying to compile my Qt5 application (using protobuf) into wasm following [Qt instructions](https://doc.qt.io/qt-5/wasm.html). But the compilation fails at the last generated file which is the application js file and it's probably related to protobuf libraries. Any idea why this is happening?

- em++ : 1.39.8

- Qt 5.15.0

- project.pro qmake compilation flags

```
QMAKE_CXXFLAGS += -s USE_PTHREADS=1 -s WASM_MEM_MAX=536870912
QMAKE_CFLAGS += -s USE_PTHREADS=1 -s WASM_MEM_MAX=536870912
QMAKE_LFLAGS += -pthread -s WASM_MEM_MAX=536870912
```

- protoc : 3.15.8 (compiled as follows)

```
CC=emcc CXX=em++ AR=emar cmake .. -Dprotobuf_BUILD_SHARED_LIBS=OFF -Dprotobuf_BUILD_TESTS=OFF -DCMAKE_INSTALL_PREFIX=/home/nikolaos.sourligkas/protobuf-wasm
emmake make libprotoc libprotobuf-lite
emmake make install libprotoc libprotobuf-lite
```

- Compilation error

```
em++ -s WASM=1 -s FULL_ES2=1 -s FULL_ES3=1 -s USE_WEBGL2=1 -s EXIT_RUNTIME=1 -s ERROR_ON_UNDEFINED_SYMBOLS=1 -s EXTRA_EXPORTED_RUNTIME_METHODS=["UTF16ToString","stringToUTF16"] --bind -s FETCH=1 -pthread -s WASM_MEM_MAX=536870912 -O2 -s ALLOW_MEMORY_GROWTH=1 -o ./suntracker3-qt5.js main.o Tracking.o WindSpeed.o WindGraph.o WindGraphPoint.o FrontendInfo.o TrackerMatrix.o TrackerTelemetry.o TrackerMatrixModel.o DatabaseManager.o WebSocketClient.o suntracker3-qt5.js_plugin_import.o suntracker3-qt5.js_qml_plugin_import.o frontend.pb.o SunSpinBox_qml.o HomePage_qml.o SunHorizontalHeaderView_qml.o LineChart_qml.o SettingsPage_qml.o SunComboBox_qml.o TrackerMatrix_qml.o CButton_qml.o Login_qml.o SettingsLogin_qml.o main_qml.o qmlcache_loader.o qrc_qml_qmlcache.o moc_Tracking.o moc_WindSpeed.o moc_WindGraph.o moc_WindGraphPoint.o moc_FrontendInfo.o moc_TrackerMatrix.o moc_TrackerTelemetry.o moc_TrackerMatrixModel.o moc_DatabaseManager.o moc_WebSocketClient.o -pthread -L/home/nikolaos.sourligkas/protobuf-wasm/lib -lprotobuf /opt/Qt/5.15.0/wasm_32/plugins/virtualkeyboard/libqtvirtualkeyboard_hangul.a /opt/Qt/5.15.0/wasm_32/plugins/virtualkeyboard/libqtvirtualkeyboard_openwnn.a /opt/Qt/5.15.0/wasm_32/lib/libqtopenwnn.a /opt/Qt/5.15.0/wasm_32/plugins/virtualkeyboard/libqtvirtualkeyboard_pinyin.a /opt/Qt/5.15.0/wasm_32/lib/libqtpinyin.a /opt/Qt/5.15.0/wasm_32/plugins/virtualkeyboard/libqtvirtualkeyboard_tcime.a /opt/Qt/5.15.0/wasm_32/lib/libqttcime.a /opt/Qt/5.15.0/wasm_32/plugins/virtualkeyboard/libqtvirtualkeyboard_thai.a /opt/Qt/5.15.0/wasm_32/plugins/platforms/libqwasm.a /opt/Qt/5.15.0/wasm_32/lib/libQt5EventDispatcherSupport.a /opt/Qt/5.15.0/wasm_32/lib/libQt5FontDatabaseSupport.a /opt/Qt/5.15.0/wasm_32/lib/libqtfreetype.a /opt/Qt/5.15.0/wasm_32/lib/libQt5EglSupport.a /opt/Qt/5.15.0/wasm_32/plugins/imageformats/libqgif.a /opt/Qt/5.15.0/wasm_32/plugins/imageformats/libqicns.a /opt/Qt/5.15.0/wasm_32/plugins/imageformats/libqico.a /opt/Qt/5.15.0/wasm_32/plugins/imageformats/libqjpeg.a /opt/Qt/5.15.0/wasm_32/plugins/imageformats/libqtga.a /opt/Qt/5.15.0/wasm_32/plugins/imageformats/libqtiff.a /opt/Qt/5.15.0/wasm_32/plugins/imageformats/libqwbmp.a /opt/Qt/5.15.0/wasm_32/plugins/imageformats/libqwebp.a /opt/Qt/5.15.0/wasm_32/lib/libQt5WebSockets.a /opt/Qt/5.15.0/wasm_32/qml/QtCharts/libqtchartsqml2.a /opt/Qt/5.15.0/wasm_32/lib/libQt5Charts.a /opt/Qt/5.15.0/wasm_32/qml/QtQuick/VirtualKeyboard/libqtquickvirtualkeyboardplugin.a /opt/Qt/5.15.0/wasm_32/qml/QtQuick/Layouts/libqquicklayoutsplugin.a /opt/Qt/5.15.0/wasm_32/qml/Qt/labs/folderlistmodel/libqmlfolderlistmodelplugin.a /opt/Qt/5.15.0/wasm_32/qml/QtQuick/VirtualKeyboard/Settings/libqtquickvirtualkeyboardsettingsplugin.a /opt/Qt/5.15.0/wasm_32/qml/QtQuick/VirtualKeyboard/Styles/libqtquickvirtualkeyboardstylesplugin.a /opt/Qt/5.15.0/wasm_32/lib/libQt5VirtualKeyboard.a /opt/Qt/5.15.0/wasm_32/lib/libQt5Svg.a /opt/Qt/5.15.0/wasm_32/lib/libQt5Widgets.a /opt/Qt/5.15.0/wasm_32/qml/QtQuick.2/libqtquick2plugin.a /opt/Qt/5.15.0/wasm_32/qml/QtQuick/Templates.2/libqtquicktemplates2plugin.a /opt/Qt/5.15.0/wasm_32/qml/QtQuick/Controls.2/libqtquickcontrols2plugin.a /opt/Qt/5.15.0/wasm_32/qml/QtGraphicalEffects/private/libqtgraphicaleffectsprivate.a /opt/Qt/5.15.0/wasm_32/qml/QtQuick/Window.2/libwindowplugin.a /opt/Qt/5.15.0/wasm_32/qml/QtGraphicalEffects/libqtgraphicaleffectsplugin.a /opt/Qt/5.15.0/wasm_32/qml/QtQuick/Controls.2/Imagine/libqtquickcontrols2imaginestyleplugin.a /opt/Qt/5.15.0/wasm_32/qml/QtQuick/Controls.2/Material/libqtquickcontrols2materialstyleplugin.a /opt/Qt/5.15.0/wasm_32/qml/QtQuick/Controls.2/Fusion/libqtquickcontrols2fusionstyleplugin.a /opt/Qt/5.15.0/wasm_32/qml/QtQuick/Controls.2/Universal/libqtquickcontrols2universalstyleplugin.a /opt/Qt/5.15.0/wasm_32/lib/libQt5QuickControls2.a /opt/Qt/5.15.0/wasm_32/lib/libQt5QuickTemplates2.a /opt/Qt/5.15.0/wasm_32/lib/libQt5Quick.a /opt/Qt/5.15.0/wasm_32/lib/libQt5Gui.a /opt/Qt/5.15.0/wasm_32/lib/libqtlibpng.a /opt/Qt/5.15.0/wasm_32/lib/libqtharfbuzz.a /opt/Qt/5.15.0/wasm_32/lib/libQt5QmlModels.a /opt/Qt/5.15.0/wasm_32/lib/libQt5Qml.a /opt/Qt/5.15.0/wasm_32/lib/libQt5Network.a /opt/Qt/5.15.0/wasm_32/lib/libQt5Core.a /opt/Qt/5.15.0/wasm_32/lib/libqtpcre2.a
root:WARNING: USE_PTHREADS + ALLOW_MEMORY_GROWTH may run non-wasm code slowly, see https://github.com/WebAssembly/design/issues/1271
wasm-ld: error: 'atomics' feature is disallowed by arena.cc.o, so --shared-memory must not be used
wasm-ld: error: Target feature 'atomics' used in main.o is disallowed by arena.cc.o. Use --no-check-features to suppress.
wasm-ld: error: Target feature 'atomics' used in Tracking.o is disallowed by arena.cc.o. Use --no-check-features to suppress.
wasm-ld: error: Target feature 'atomics' used in WindSpeed.o is disallowed by arena.cc.o. Use --no-check-features to suppress.
wasm-ld: error: Target feature 'atomics' used in WindGraph.o is disallowed by arena.cc.o. Use --no-check-features to suppress.
wasm-ld: error: Target feature 'atomics' used in WindGraphPoint.o is disallowed by arena.cc.o. Use --no-check-features to suppress.
wasm-ld: error: Target feature 'atomics' used in FrontendInfo.o is disallowed by arena.cc.o. Use --no-check-features to suppress.
wasm-ld: error: Target feature 'atomics' used in TrackerMatrix.o is disallowed by arena.cc.o. Use --no-check-features to suppress.
wasm-ld: error: Target feature 'atomics' used in TrackerTelemetry.o is disallowed by arena.cc.o. Use --no-check-features to suppress.
wasm-ld: error: Target feature 'atomics' used in TrackerMatrixModel.o is disallowed by arena.cc.o. Use --no-check-features to suppress.
wasm-ld: error: Target feature 'atomics' used in DatabaseManager.o is disallowed by arena.cc.o. Use --no-check-features to suppress.
wasm-ld: error: Target feature 'atomics' used in WebSocketClient.o is disallowed by arena.cc.o. Use --no-check-features to suppress.
wasm-ld: error: Target feature 'atomics' used in suntracker3-qt5.js_plugin_import.o is disallowed by arena.cc.o. Use --no-check-features to suppress.
wasm-ld: error: Target feature 'atomics' used in suntracker3-qt5.js_qml_plugin_import.o is disallowed by arena.cc.o. Use --no-check-features to suppress.
wasm-ld: error: Target feature 'atomics' used in frontend.pb.o is disallowed by arena.cc.o. Use --no-check-features to suppress.
wasm-ld: error: Target feature 'atomics' used in SunSpinBox_qml.o is disallowed by arena.cc.o. Use --no-check-features to suppress.
wasm-ld: error: Target feature 'atomics' used in HomePage_qml.o is disallowed by arena.cc.o. Use --no-check-features to suppress.
wasm-ld: error: Target feature 'atomics' used in SunHorizontalHeaderView_qml.o is disallowed by arena.cc.o. Use --no-check-features to suppress.
wasm-ld: error: Target feature 'atomics' used in LineChart_qml.o is disallowed by arena.cc.o. Use --no-check-features to suppress.
wasm-ld: error: Target feature 'atomics' used in SettingsPage_qml.o is disallowed by arena.cc.o. Use --no-check-features to suppress.
wasm-ld: error: too many errors emitted, stopping now (use -error-limit=0 to see all errors)
shared:ERROR: '/home/nikolaos.sourligkas/emsdk/upstream/bin/wasm-ld -o /tmp/emscripten_temp_nvijanr4/suntracker3-qt5.wasm --lto-O0 main.o Tracking.o WindSpeed.o -L/home/nikolaos.sourligkas/emsdk/upstream/emscripten/system/local/lib WindGraph.o -L/home/nikolaos.sourligkas/emsdk/upstream/emscripten/system/lib WindGraphPoint.o -L/home/nikolaos.sourligkas/emsdk/upstream/emscripten/cache/wasm-obj FrontendInfo.o TrackerMatrix.o TrackerTelemetry.o TrackerMatrixModel.o DatabaseManager.o WebSocketClient.o suntracker3-qt5.js_plugin_import.o suntracker3-qt5.js_qml_plugin_import.o frontend.pb.o SunSpinBox_qml.o HomePage_qml.o SunHorizontalHeaderView_qml.o LineChart_qml.o SettingsPage_qml.o SunComboBox_qml.o TrackerMatrix_qml.o CButton_qml.o Login_qml.o SettingsLogin_qml.o main_qml.o qmlcache_loader.o qrc_qml_qmlcache.o moc_Tracking.o moc_WindSpeed.o moc_WindGraph.o moc_WindGraphPoint.o moc_FrontendInfo.o moc_TrackerMatrix.o moc_TrackerTelemetry.o moc_TrackerMatrixModel.o moc_DatabaseManager.o moc_WebSocketClient.o -L/home/nikolaos.sourligkas/protobuf-wasm/lib /home/nikolaos.sourligkas/protobuf-wasm/lib/libprotobuf.a /opt/Qt/5.15.0/wasm_32/plugins/virtualkeyboard/libqtvirtualkeyboard_hangul.a /opt/Qt/5.15.0/wasm_32/plugins/virtualkeyboard/libqtvirtualkeyboard_openwnn.a /opt/Qt/5.15.0/wasm_32/lib/libqtopenwnn.a /opt/Qt/5.15.0/wasm_32/plugins/virtualkeyboard/libqtvirtualkeyboard_pinyin.a /opt/Qt/5.15.0/wasm_32/lib/libqtpinyin.a /opt/Qt/5.15.0/wasm_32/plugins/virtualkeyboard/libqtvirtualkeyboard_tcime.a /opt/Qt/5.15.0/wasm_32/lib/libqttcime.a /opt/Qt/5.15.0/wasm_32/plugins/virtualkeyboard/libqtvirtualkeyboard_thai.a /opt/Qt/5.15.0/wasm_32/plugins/platforms/libqwasm.a /opt/Qt/5.15.0/wasm_32/lib/libQt5EventDispatcherSupport.a /opt/Qt/5.15.0/wasm_32/lib/libQt5FontDatabaseSupport.a /opt/Qt/5.15.0/wasm_32/lib/libqtfreetype.a /opt/Qt/5.15.0/wasm_32/lib/libQt5EglSupport.a /opt/Qt/5.15.0/wasm_32/plugins/imageformats/libqgif.a /opt/Qt/5.15.0/wasm_32/plugins/imageformats/libqicns.a /opt/Qt/5.15.0/wasm_32/plugins/imageformats/libqico.a /opt/Qt/5.15.0/wasm_32/plugins/imageformats/libqjpeg.a /opt/Qt/5.15.0/wasm_32/plugins/imageformats/libqtga.a /opt/Qt/5.15.0/wasm_32/plugins/imageformats/libqtiff.a /opt/Qt/5.15.0/wasm_32/plugins/imageformats/libqwbmp.a /opt/Qt/5.15.0/wasm_32/plugins/imageformats/libqwebp.a /opt/Qt/5.15.0/wasm_32/lib/libQt5WebSockets.a /opt/Qt/5.15.0/wasm_32/qml/QtCharts/libqtchartsqml2.a /opt/Qt/5.15.0/wasm_32/lib/libQt5Charts.a /opt/Qt/5.15.0/wasm_32/qml/QtQuick/VirtualKeyboard/libqtquickvirtualkeyboardplugin.a /opt/Qt/5.15.0/wasm_32/qml/QtQuick/Layouts/libqquicklayoutsplugin.a /opt/Qt/5.15.0/wasm_32/qml/Qt/labs/folderlistmodel/libqmlfolderlistmodelplugin.a /opt/Qt/5.15.0/wasm_32/qml/QtQuick/VirtualKeyboard/Settings/libqtquickvirtualkeyboardsettingsplugin.a /opt/Qt/5.15.0/wasm_32/qml/QtQuick/VirtualKeyboard/Styles/libqtquickvirtualkeyboardstylesplugin.a /opt/Qt/5.15.0/wasm_32/lib/libQt5VirtualKeyboard.a /opt/Qt/5.15.0/wasm_32/lib/libQt5Svg.a /opt/Qt/5.15.0/wasm_32/lib/libQt5Widgets.a /opt/Qt/5.15.0/wasm_32/qml/QtQuick.2/libqtquick2plugin.a /opt/Qt/5.15.0/wasm_32/qml/QtQuick/Templates.2/libqtquicktemplates2plugin.a /opt/Qt/5.15.0/wasm_32/qml/QtQuick/Controls.2/libqtquickcontrols2plugin.a /opt/Qt/5.15.0/wasm_32/qml/QtGraphicalEffects/private/libqtgraphicaleffectsprivate.a /opt/Qt/5.15.0/wasm_32/qml/QtQuick/Window.2/libwindowplugin.a /opt/Qt/5.15.0/wasm_32/qml/QtGraphicalEffects/libqtgraphicaleffectsplugin.a /opt/Qt/5.15.0/wasm_32/qml/QtQuick/Controls.2/Imagine/libqtquickcontrols2imaginestyleplugin.a /opt/Qt/5.15.0/wasm_32/qml/QtQuick/Controls.2/Material/libqtquickcontrols2materialstyleplugin.a /opt/Qt/5.15.0/wasm_32/qml/QtQuick/Controls.2/Fusion/libqtquickcontrols2fusionstyleplugin.a /opt/Qt/5.15.0/wasm_32/qml/QtQuick/Controls.2/Universal/libqtquickcontrols2universalstyleplugin.a /opt/Qt/5.15.0/wasm_32/lib/libQt5QuickControls2.a /opt/Qt/5.15.0/wasm_32/lib/libQt5QuickTemplates2.a /opt/Qt/5.15.0/wasm_32/lib/libQt5Quick.a /opt/Qt/5.15.0/wasm_32/lib/libQt5Gui.a /opt/Qt/5.15.0/wasm_32/lib/libqtlibpng.a /opt/Qt/5.15.0/wasm_32/lib/libqtharfbuzz.a /opt/Qt/5.15.0/wasm_32/lib/libQt5QmlModels.a /opt/Qt/5.15.0/wasm_32/lib/libQt5Qml.a /opt/Qt/5.15.0/wasm_32/lib/libQt5Network.a /opt/Qt/5.15.0/wasm_32/lib/libQt5Core.a /opt/Qt/5.15.0/wasm_32/lib/libqtpcre2.a /home/nikolaos.sourligkas/emsdk/upstream/emscripten/cache/wasm-obj/libc-mt.a /home/nikolaos.sourligkas/emsdk/upstream/emscripten/cache/wasm-obj/libcompiler_rt.a /home/nikolaos.sourligkas/emsdk/upstream/emscripten/cache/wasm-obj/libc-wasm.a /home/nikolaos.sourligkas/emsdk/upstream/emscripten/cache/wasm-obj/libc++-mt-noexcept.a /home/nikolaos.sourligkas/emsdk/upstream/emscripten/cache/wasm-obj/libc++abi-mt-noexcept.a --whole-archive /home/nikolaos.sourligkas/emsdk/upstream/emscripten/cache/wasm-obj/libembind-rtti.a /home/nikolaos.sourligkas/emsdk/upstream/emscripten/cache/wasm-obj/libfetch-mt.a --no-whole-archive /home/nikolaos.sourligkas/emsdk/upstream/emscripten/cache/wasm-obj/libgl-mt-webgl2-full_es3.a /home/nikolaos.sourligkas/emsdk/upstream/emscripten/cache/wasm-obj/libdlmalloc-mt.a /home/nikolaos.sourligkas/emsdk/upstream/emscripten/cache/wasm-obj/libpthread-mt.a /home/nikolaos.sourligkas/emsdk/upstream/emscripten/cache/wasm-obj/libc_rt_wasm.a /home/nikolaos.sourligkas/emsdk/upstream/emscripten/cache/wasm-obj/libsockets-mt.a --allow-undefined --import-memory --import-table --shared-memory -mllvm -combiner-global-alias-analysis=false -mllvm -enable-emscripten-sjlj -mllvm -disable-lsr --strip-debug --export __wasm_call_ctors --export __data_end --export main --export malloc --export free --export setThrew --export __errno_location --export fflush --export emscripten_get_global_libc --export __pthread_tsd_run_dtors --export _register_pthread_ptr --export pthread_self --export __emscripten_pthread_data_constructor --export emscripten_futex_wake --export memalign --export _ZSt18uncaught_exceptionv --export emscripten_GetProcAddress --export strstr --export emscripten_webgl_make_context_current --export emscripten_webgl_get_current_context --export emscripten_builtin_free --export _get_environ --export emscripten_builtin_memalign --export realloc --export _get_tzname --export _get_daylight --export _get_timezone --export htonl --export htons --export ntohs --export strlen -z stack-size=5242880 --initial-memory=16777216 --no-entry --max-memory=536870912 --global-base=1024' failed (1)
Makefile:311: recipe for target 'suntracker3-qt5.js' failed
make: *** [suntracker3-qt5.js] Error 1
15:58:42: The process "/usr/bin/make" exited with code 2.
Error while building/deploying project suntracker3-qt5 (kit: Qt 5.15.0 WebAssembly)
When executing step "Make"
15:58:42: Elapsed time: 00:15.
```