newbie question: GC-safe

[spamsalty]

here is a code
    
    
    import httpclient, asyncdispatch
    
    proc a() {.async.} =
        var client = newAsyncHttpClient()
        var b = await client.getContent("http://google.com";)
        echo b
    
    waitFor a()
    echo "done"
    

if i compile it, it compiles good and runs as i expected.

however how can i surpress the compiler warning message?

" lib/pure/asyncmacro.nim(291, 7) Hint: Processing a as an async proc. [User] 
get.nim(3, 10) template/generic instantiation from here 
lib/pure/asyncmacro.nim(31, 8) Warning: 'cb' is not GC-safe as it accesses 
'nameIterVar' which is a global using GC'ed memory [GcUnsafe2] "

thank you.