> I assume that the reason why most of these failing tests are failing is not a regression in core functionality of Make but rather because of new features were

> I assume that the reason why most of these failing tests are failing is not a regression in core functionality of Make but rather because of new features were added to GNU Make since 2006. There were a number of bugs in the 3.81 release that I assume they now have tests for, since 4.x has been rock solid. (Off the top of my head, if you made a certain shape in the dependency graph with .PHONY targets, then .DELETE_ON_ERROR stopped working)