Closure optimization + keeping function name

I have simple example:

Javascript:

function testBut(b){
   alert("!");
}

HTML:

<button onclick="testBut(this)">Test</button>

Now I run my .js script through Google Closure compiler (running from commandline), and I want to keep testBut function intact.

I read in many places that I have to use --externs option and define another file with names of exported functions, in this case it would hold just:

function testBut(b){}

And additionally I need to add funny line to my js code:

window['testBut']=testBut;

So now questions:

• is that really so stupid system in Closure with two bug-prone steps to be done, in order to keep desired function?

• is there no "@..." annotation that would simply suit same purpose? I tried @export, but it requires --generate_exports option, and still it generates similar ugly and useless goog.a("testBut", testBut); in target code (I tried same code, and those goog.a(...) seems simply useless), and this still requires the exports file

Ideally I'm looking for simple annotation or commandline switch that would tell "don't remove/rename this function", as simple as possible, no code added, no another file.

Thanks