Our js files have defined google closure compiler types at jsdoc entries but these jsdoc entries are removed by cpp preprocessor. I considered that reusing them in javascript-backend would be a nice thing. Right now haskell processor uses `-traditional` option to deal with comments and `//` operators.
But now there are following compiler options: `-C` and `-CC`.
You can read about them at GCC (see https://gcc.gnu.org/onlinedocs/gcc/Preprocessor-Options.html#index-CC) and CLang (see https://clang.llvm.org/docs/ClangCommandLineReference.html#cmdoption-clang-CC).
It seems that `-CC` works better for javascript jsdoc than `-traditional`.
At least it leaves `/* ... */` comments w/o changes.