Add an internal setting to track whether closure might be run (#20208)

This new internal setting is true if we run it, or if the user might run it.

Use that new setting to gate when to add closure annotations, which should
fix remaining issues with closure in emcc working but not after it.

Author: kripken

emcc.py

@@ -2972,6 +2972,15 @@ def get_full_import_name(name):
 
   settings.MINIFY_WHITESPACE = settings.OPT_LEVEL >= 2 and settings.DEBUG_LEVEL == 0 and not options.no_minify
 
+  # Closure might be run if we run it ourselves, or if whitespace is not being
+  # minifed. In the latter case we keep both whitespace and comments, and the
+  # purpose of the comments might be closure compiler, so also perform all
+  # adjustments necessary to ensure that works (which amounts to a few more
+  # comments; adding some more of them is not an issue in such a build which
+  # includes all comments and whitespace anyhow).
+  if settings.USE_CLOSURE_COMPILER or not settings.MINIFY_WHITESPACE:
+    settings.MAYBE_CLOSURE_COMPILER = 1
+
   return target, wasm_target
 
 

emscripten.py

@@ -729,12 +729,9 @@ def create_sending(metadata, library_symbols):
 
   sorted_items = sorted(send_items_map.items())
   prefix = ''
-  if settings.USE_CLOSURE_COMPILER or not settings.MINIFY_WHITESPACE:
+  if settings.MAYBE_CLOSURE_COMPILER:
     # This prevents closure compiler from minifying the field names in this
-    # object. Note that we also apply this when whitespace is not minified so
-    # that closure can be run on the output later, after emscripten runs (and
-    # when whitespace is present we keep comments as well, so adding more
-    # comments is not an issue).
+    # object.
     prefix = '/** @export */\n  '
   return '{\n  ' + ',\n  '.join(f'{prefix}{k}: {v}' for k, v in sorted_items) + '\n}'
 

src/library_browser.js

@@ -902,7 +902,7 @@ var LibraryBrowser = {
     Browser.mainLoop.func = browserIterationFunc;
     Browser.mainLoop.arg = arg;
 
-#if USE_CLOSURE_COMPILER
+#if MAYBE_CLOSURE_COMPILER
     // Closure compiler bug(?): Closure does not see that the assignment
     //   var thisMainLoopId = Browser.mainLoop.currentlyRunningMainloop
     // is a value copy of a number (even with the JSDoc @type annotation)

src/library_glemu.js

@@ -8,7 +8,7 @@ var LibraryGLEmulation = {
   // GL emulation: provides misc. functionality not present in OpenGL ES 2.0 or WebGL
   $GLEmulation__deps: ['$GLImmediateSetup', 'glEnable', 'glDisable', 'glIsEnabled', 'glGetBooleanv', 'glGetIntegerv', 'glGetString', 'glCreateShader', 'glShaderSource', 'glCompileShader', 'glAttachShader', 'glDetachShader', 'glUseProgram', 'glDeleteProgram', 'glBindAttribLocation', 'glLinkProgram', 'glBindBuffer', 'glGetFloatv', 'glHint', 'glEnableVertexAttribArray', 'glDisableVertexAttribArray', 'glVertexAttribPointer', 'glActiveTexture', '$stringToNewUTF8', '$ptrToString'],
   $GLEmulation__postset:
-#if USE_CLOSURE_COMPILER
+#if MAYBE_CLOSURE_COMPILER
     // Forward declare GL functions that are overridden by GLEmulation here to appease Closure compiler.
     '/**@suppress {duplicate, undefinedVars}*/var _emscripten_glDrawArrays;' +
     '/**@suppress {duplicate, undefinedVars}*/var _emscripten_glDrawElements;' +

src/library_pthread.js

@@ -119,7 +119,7 @@ var LibraryPThread = {
     },
 
     initWorker() {
-#if USE_CLOSURE_COMPILER
+#if MAYBE_CLOSURE_COMPILER
       // worker.js is not compiled together with us, and must access certain
       // things.
       PThread['receiveObjectTransfer'] = PThread.receiveObjectTransfer;

src/settings_internal.js

@@ -238,6 +238,11 @@ var HAS_MAIN = false;
 // Set to true if we are linking as C++ and including C++ stdlibs
 var LINK_AS_CXX = false;
 
+// Set when closure compiler may be run: Either emcc will run it, or the user
+// might run it after emcc. Either way, some JS changes and annotations must be
+// emitted in that case for closure compiler.
+var MAYBE_CLOSURE_COMPILER = false;
+
 // Set when some minimum browser version triggers doesn't support the
 // minimum set of ES6 features.  This triggers transpilation to ES5
 // using closure compiler.

tools/building.py

@@ -337,9 +337,9 @@ def acorn_optimizer(filename, passes, extra_info=None, return_output=False):
       f.write('// EXTRA_INFO: ' + extra_info)
     filename = temp
   cmd = config.NODE_JS + [optimizer, filename] + passes
-  # Keep JS code comments intact through the acorn optimization pass so that JSDoc comments
-  # will be carried over to a later Closure run.
-  if settings.USE_CLOSURE_COMPILER or not settings.MINIFY_WHITESPACE:
+  # Keep JS code comments intact through the acorn optimization pass so that
+  # JSDoc comments will be carried over to a later Closure run.
+  if settings.MAYBE_CLOSURE_COMPILER:
     cmd += ['--closureFriendly']
   if settings.EXPORT_ES6:
     cmd += ['--exportES6']
@@ -681,7 +681,7 @@ def minify_wasm_js(js_file, wasm_file, expensive_optimizations, debug_info):
   if not settings.LINKABLE:
     passes.append('JSDCE' if not expensive_optimizations else 'AJSDCE')
   # Don't minify if we are going to run closure compiler afterwards
-  minify = settings.MINIFY_WHITESPACE and not settings.USE_CLOSURE_COMPILER
+  minify = settings.MINIFY_WHITESPACE and not settings.MAYBE_CLOSURE_COMPILER
   if minify:
     passes.append('minifyWhitespace')
   if passes: