I see this is a really old question. I'm not sure if anyone is actually using VS 2013 anymore, but it works in VS2017, exactly the way it's done in the question.
But! I had to run Build -> Clean Solution first before it worked. 'Rebuild Solution' didn't even do it. I had to Clean first, then build and run it.
I tested it with this code:
#if DEBUG
Console.WriteLine("DEBUG");;
#endif
#if TRACE
Console.WriteLine("TRACE");
#endif
#if __MY_NEW_SYMBOL__
Console.WriteLine("__MY_NEW_SYMBOL__");
#endif
Even though my .user file only defines __MY_NEW_SYMBOL__
, I saw all three in the console after running it.
My .csproj file has this:
<PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
<DefineConstants>DEBUG;TRACE</DefineConstants>
</PropertyGroup>
And my .csproj.user file has this:
<PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
<DefineConstants>$(DefineConstants);__MY_NEW_SYMBOL__</DefineConstants>
</PropertyGroup>