File Tracker Log file format

This stuff doesn't seem to be documented anywhere, so I've had to figure this out based on trial and error and by staring at some example targets/xml/props files:

The reason the custom build step writes to the tlog file by hand is that Build|Clean - and probably its command line counterpart - scrapes the tlog files to find which files to delete. It seems to look for all files matching *.write.tlog, or maybe *.1.write.tlog, in the intermediate folder, read the list of file names in each, and delete the files named. So, if the custom build steps knows what its outputs are, it can simply record them in a tlog file, and interact with Build|Clean that way.

(You can try this out yourself - build your project, create some temp files, add your own tlog file to your project's intermediate folder containing the paths to the temp files, then do a Build|Clean. Your temp files will be deleted along with the usual build artefacts.)

In a tlog file, a file with no prefix is the name of an output file. These files are deleted when you do a Build|Clean.

A file with a ^ before it a comment, I think - perhaps obviously, Build|Clean doesn't touch any of these.

As for |, I've only seen it in comment lines, used to separate different file names. I suspect this is just a convention, and not some special syntax, since if you put multiple output files on line, separated by |, Build|Clean doesn't delete them.

The tlog file format is now documented here: https://docs.microsoft.com/en-us/visualstudio/extensibility/visual-cpp-project-extensibility?view=vs-2017#tlog-files

Read .tlog format

Read .tlog files (.read..tlog) contain information about source files and their dependencies.

A caret (^) at the beginning of a line indicates one or more sources. Sources that share the same dependencies are separated by a vertical bar (|).

Dependency files are listed after the sources, each on its own line. All file names are full paths.