Avoid errors in binaryen.js assertions builds, and enable ASSERTIONS in debug builds. (#2507)

Author: kripken

CMakeLists.txt

@@ -366,6 +366,7 @@ if(EMSCRIPTEN)
   target_link_libraries(binaryen_js optimized "--closure 1")
   target_link_libraries(binaryen_js optimized "--llvm-lto 1")
   target_link_libraries(binaryen_js debug "--profiling")
+  target_link_libraries(binaryen_js debug "-s ASSERTIONS")
   set_property(TARGET binaryen_js PROPERTY CXX_STANDARD 14)
   set_property(TARGET binaryen_js PROPERTY CXX_STANDARD_REQUIRED ON)
   install(TARGETS binaryen_js DESTINATION ${CMAKE_INSTALL_BINDIR})

src/js/binaryen.js-post.js

@@ -2768,6 +2768,12 @@ Module['emitText'] = function(expr) {
 };
 
 // Parses a binary to a module
+
+// If building with Emscripten ASSERTIONS, there is a property added to
+// Module to guard against users mistakening using the removed readBinary()
+// API. We must defuse that carefully.
+Object.defineProperty(Module, 'readBinary', { writable: true });
+
 Module['readBinary'] = function(data) {
   var buffer = allocate(data, 'i8', ALLOC_NORMAL);
   var ptr = Module['_BinaryenModuleRead'](buffer, data.length);