New Windows installer should test for VC runtime and provide a URL if missing
I understand that there's a GPL provision that prevents bundling the Meld installer with the installer for the runtime it depends on, but I believe it should be permissible to test if the user needs to install the runtime and prompt them to download and install it if necessary.
I found this old blog post about checking installation status for a previous version, which lists the relevant API call, but you'd have to look up the GUIDs for the version of the runtime you actually need. (ETA: see also)
Edited by Ghost User