Remove --proxy-to-worker/-sPROXY_TO_WORKER (emscripten-core#25645)

This is pretty large, and complex feature that (as far as we can tell)
had no users. See emscripten-core#25440 for more details on the deprecation planning.

Fixes: emscripten-core#25440

Author: sbc100

ChangeLog.md

@@ -20,6 +20,10 @@ See docs/process.md for more on how version tagging works.
 
 4.0.21 (in development)
 -----------------------
+- The `-sPROXY_TO_WORKER` setting (along with the corresponding
+  `--proxy-to-worker` flag) was removed due to lack of usage.  If you were
+  depending on this feature but missed the PSA, please let us know about your
+  use case. (#25645, #25440)
 
 4.0.20 - 11/18/25
 -----------------

site/source/docs/api_reference/module.rst

@@ -174,10 +174,6 @@ Other methods
 
   .. note:: Sanitizers or source map is currently not supported if overriding WebAssembly instantiation with Module.instantiateWasm. Providing Module.instantiateWasm when source map or sanitizer is enabled can prevent WebAssembly instantiation from finishing.
 
-.. js:function:: Module.onCustomMessage
-
-  When compiled with ``PROXY_TO_WORKER = 1`` (see `settings.js <https://github.com/emscripten-core/emscripten/blob/main/src/settings.js>`_), this callback (which should be implemented on both the client and worker's ``Module`` object) allows sending custom messages and data between the web worker and the main thread (using the ``postCustomMessage`` function defined in `proxyClient.js <https://github.com/emscripten-core/emscripten/blob/main/src/proxyClient.js>`_ and `proxyWorker.js <https://github.com/emscripten-core/emscripten/blob/main/src/proxyWorker.js>`_).
-
 .. js:function:: Module.fetchSettings
 
   Override the default settings object used when fetching the Wasm module from

site/source/docs/api_reference/wasm_workers.rst

@@ -396,7 +396,6 @@ The following build options are not supported at the moment with Wasm Workers:
 
 - -sSINGLE_FILE
 - Dynamic linking (-sLINKABLE, -sMAIN_MODULE, -sSIDE_MODULE)
-- -sPROXY_TO_WORKER
 - -sPROXY_TO_PTHREAD
 
 Example Code

site/source/docs/tools_reference/settings_reference.rst

@@ -1683,31 +1683,6 @@ in a worker. See emscripten.h
 
 Default value: false
 
-.. _proxy_to_worker:
-
-PROXY_TO_WORKER
-===============
-
-If set to 1, we build the project into a js file that will run in a worker,
-and generate an html file that proxies input and output to/from it.
-
-.. note:: This setting is deprecated
-
-Default value: false
-
-.. _proxy_to_worker_filename:
-
-PROXY_TO_WORKER_FILENAME
-========================
-
-If set, the script file name the main thread loads.  Useful if your project
-doesn't run the main emscripten- generated script immediately but does some
-setup before
-
-.. note:: This setting is deprecated
-
-Default value: ''
-
 .. _proxy_to_pthread:
 
 PROXY_TO_PTHREAD
@@ -3431,8 +3406,6 @@ the these settings please open a bug (or reply to one of the existing bugs).
  - ``ASYNCIFY_EXPORTS``: please use JSPI_EXPORTS instead
  - ``LINKABLE``: under consideration for removal (https://github.com/emscripten-core/emscripten/issues/25262)
  - ``RELOCATABLE``:  under consideration for removal (https://github.com/emscripten-core/emscripten/issues/25262)
- - ``PROXY_TO_WORKER``: under consideration for removal (See https://github.com/emscripten-core/emscripten/issues/25440)
- - ``PROXY_TO_WORKER_FILENAME``: under consideration for removal (See https://github.com/emscripten-core/emscripten/issues/25440)
 
 .. _legacy-settings:
 
@@ -3518,3 +3491,4 @@ for backwards compatbility with older versions:
  - ``USE_OFFSET_COVERTER``: No longer supported, not needed with modern v8 versions (Valid values: [0])
  - ``ASYNCIFY_LAZY_LOAD_CODE``: No longer supported (Valid values: [0])
  - ``USE_WEBGPU``: No longer supported; replaced by --use-port=emdawnwebgpu, which implements a newer (but incompatible) version of webgpu.h - see tools/ports/emdawnwebgpu.py (Valid values: [0])
+ - ``PROXY_TO_WORKER``: No longer supported (Valid values: [0])

src/lib/libegl.js

@@ -637,10 +637,6 @@ var LibraryEGL = {
   eglSwapBuffers__deps: ['$GLctx'],
   eglSwapBuffers__proxy: 'sync',
   eglSwapBuffers: (dpy, surface) => {
-#if PROXY_TO_WORKER
-    if (Browser.doSwapBuffers) Browser.doSwapBuffers();
-#endif
-
     if (!EGL.defaultDisplayInitialized) {
       EGL.setErrorCode(0x3001 /* EGL_NOT_INITIALIZED */);
     } else if (!GLctx) {

src/lib/libidbstore.js

@@ -144,67 +144,6 @@ var LibraryIDBStore = {
       wakeUp();
     });
   }),
-  // extra worker methods - proxied
-  emscripten_idb_load_blob__async: true,
-  emscripten_idb_load_blob: (db, id, pblob, perror) => Asyncify.handleSleep((wakeUp) => {
-#if ASSERTIONS
-    assert(!IDBStore.pending);
-#endif
-    IDBStore.pending = (msg) => {
-      IDBStore.pending = null;
-      var blob = msg.blob;
-      if (!blob) {
-        {{{ makeSetValue('perror', 0, '1', 'i32') }}};
-        wakeUp();
-        return;
-      }
-#if ASSERTIONS
-      assert(blob instanceof Blob);
-#endif
-      var blobId = IDBStore.blobs.length;
-      IDBStore.blobs.push(blob);
-      {{{ makeSetValue('pblob', 0, 'blobId', 'i32') }}};
-      wakeUp();
-    };
-    postMessage({
-      target: 'IDBStore',
-      method: 'loadBlob',
-      db: UTF8ToString(db),
-      id: UTF8ToString(id)
-    });
-  }),
-  emscripten_idb_store_blob__async: true,
-  emscripten_idb_store_blob: (db, id, ptr, num, perror) => Asyncify.handleSleep((wakeUp) => {
-#if ASSERTIONS
-    assert(!IDBStore.pending);
-#endif
-    IDBStore.pending = (msg) => {
-      IDBStore.pending = null;
-      {{{ makeSetValue('perror', 0, '!!msg.error', 'i32') }}};
-      wakeUp();
-    };
-    postMessage({
-      target: 'IDBStore',
-      method: 'storeBlob',
-      db: UTF8ToString(db),
-      id: UTF8ToString(id),
-      blob: new Blob([new Uint8Array(HEAPU8.subarray(ptr, ptr+num))])
-    });
-  }),
-  emscripten_idb_read_from_blob: (blobId, start, num, buffer) => {
-    var blob = IDBStore.blobs[blobId];
-    if (!blob) return 1;
-    if (start+num > blob.size) return 2;
-    var byteArray = (new FileReaderSync()).readAsArrayBuffer(blob.slice(start, start+num));
-    HEAPU8.set(new Uint8Array(byteArray), buffer);
-    return 0;
-  },
-  emscripten_idb_free_blob: (blobId) => {
-#if ASSERTIONS
-    assert(IDBStore.blobs[blobId]);
-#endif
-    IDBStore.blobs[blobId] = null;
-  },
 #else
   emscripten_idb_load: (db, id, pbuffer, pnum, perror) => {
     abort('Please compile your program with async support in order to use synchronous operations like emscripten_idb_load, etc.');

src/lib/libsigs.js

@@ -675,12 +675,8 @@ sigs = {
   emscripten_idb_clear__sig: 'vpp',
   emscripten_idb_delete__sig: 'vppp',
   emscripten_idb_exists__sig: 'vpppp',
-  emscripten_idb_free_blob__sig: 'vi',
   emscripten_idb_load__sig: 'vppppp',
-  emscripten_idb_load_blob__sig: 'vpppp',
-  emscripten_idb_read_from_blob__sig: 'viiip',
   emscripten_idb_store__sig: 'vpppip',
-  emscripten_idb_store_blob__sig: 'vpppip',
   emscripten_is_webgl_context_lost__sig: 'ip',
   emscripten_lock_async_acquire__sig: 'vpppd',
   emscripten_lock_orientation__sig: 'ii',

src/lib/libwasm_worker.js

@@ -18,9 +18,6 @@
 #if RELOCATABLE || MAIN_MODULE
 #error "dynamic linking is not supported with -sWASM_WORKERS"
 #endif
-#if PROXY_TO_WORKER
-#error "-sPROXY_TO_WORKER is not supported with -sWASM_WORKERS"
-#endif
 #if WASM2JS && MODULARIZE
 #error "-sWASM=0 + -sMODULARIZE + -sWASM_WORKERS is not supported"
 #endif

src/postamble.js

@@ -6,13 +6,6 @@
 
 // === Auto-generated postamble setup entry stuff ===
 
-#if PROXY_TO_WORKER
-if (ENVIRONMENT_IS_WORKER) {
-#include "webGLWorker.js"
-#include "proxyWorker.js"
-}
-#endif
-
 #if LOAD_SOURCE_MAP
 #include "source_map_support.js"
 #endif