File compare/merge

[SomeDude]

On Monday, 1 April 2013 at 19:53:23 UTC, Walter Bright wrote:
> Life has gotten a lot easier for me trying to manage multiple 
> branches of D since I've been using file compare/merge tools.
>
> I use winmerge for Windows, and meld for Linux. They are both 
> free, and work great.
>
> What do you use?

I am surprised there is still no "smart" diff/merge tool, by 
which I mean one which understands the syntax of languages and or 
detects syntaxic or semantic errors in the merged file, or better 
yet, compares code based on the syntax.