Only export user-requests symbols on the Module object. NFC

Some exports are only needed internally and those don't need to be
exported on the Module object.  This is save some space and avoids
unexpected exports on the public-facing Module.

Author: sbc100

emscripten.py

@@ -796,6 +796,10 @@ def make_export_wrappers(exports, delay_assignment):
     if name == '__cpp_exception':
       continue
     mangled = asmjs_mangle(name)
+    if mangled in building.user_requested_exports or name.startswith('dynCall_'):
+      lhs = f'{mangled} = Module["{mangled}"]'
+    else:
+      lhs = f'{mangled}'
     # The emscripten stack functions are called very early (by writeStackCookie) before
     # the runtime is initialized so we can't create these wrappers that check for
     # runtimeInitialized.
@@ -805,27 +809,27 @@ def make_export_wrappers(exports, delay_assignment):
       if delay_assignment:
         wrappers.append('''\
 /** @type {function(...*):?} */
-var %(mangled)s = Module["%(mangled)s"] = createExportWrapper("%(name)s");
-''' % {'mangled': mangled, 'name': name})
+var %(lhs)s = createExportWrapper("%(name)s");
+''' % {'lhs': lhs, 'mangled': mangled, 'name': name})
       else:
         wrappers.append('''\
 /** @type {function(...*):?} */
-var %(mangled)s = Module["%(mangled)s"] = createExportWrapper("%(name)s", asm);
-''' % {'mangled': mangled, 'name': name})
+var %(lhs)s = createExportWrapper("%(name)s", asm);
+''' % {'lhs': lhs, 'mangled': mangled, 'name': name})
     elif delay_assignment:
       # With assertions disabled the wrapper will replace the global var and Module var on
       # first use.
       wrappers.append('''\
 /** @type {function(...*):?} */
-var %(mangled)s = Module["%(mangled)s"] = function() {
-  return (%(mangled)s = Module["%(mangled)s"] = Module["asm"]["%(name)s"]).apply(null, arguments);
+var %(lhs)s = function() {
+  return (%(lhs)s = Module["asm"]["%(name)s"]).apply(null, arguments);
 };
-''' % {'mangled': mangled, 'name': name})
+''' % {'lhs': lhs, 'mangled': mangled, 'name': name})
     else:
       wrappers.append('''\
 /** @type {function(...*):?} */
-var %(mangled)s = Module["%(mangled)s"] = asm["%(name)s"]
-''' % {'mangled': mangled, 'name': name})
+var %(lhs)s = asm["%(name)s"]
+''' % {'lhs': lhs, 'mangled': mangled, 'name': name})
   return wrappers
 
 

tests/other/metadce/test_metadce_cxx_ctors1.jssize

@@ -1 +1 @@
-26202
+25730

tests/other/metadce/test_metadce_cxx_ctors2.jssize

@@ -1 +1 @@
-26166
+25694

tests/other/metadce/test_metadce_cxx_except.jssize

@@ -1 +1 @@
-31596
+31080

tests/other/metadce/test_metadce_cxx_except_wasm.jssize

@@ -1 +1 @@
-26356
+25708

tests/other/metadce/test_metadce_cxx_mangle.jssize

@@ -1 +1 @@
-31696
+31080

tests/other/metadce/test_metadce_cxx_noexcept.jssize

@@ -1 +1 @@
-26202
+25730

tests/other/metadce/test_metadce_hello_O0.jssize

@@ -1 +1 @@
-26698
+26111

tests/other/metadce/test_metadce_hello_O1.jssize

@@ -1 +1 @@
-9245
+8709

tests/other/metadce/test_metadce_hello_O2.jssize

@@ -1 +1 @@
-6640
+6168