The comments at the top of the project's make file includes this sentence:
# Note: Any changes made to this Makefile will be lost the next time the
# matching project file is loaded into the IDDE.
This implies the makefile will be rebuilt when I load the project file into VisualDSP++. After closing the project and reopening this did not happen as indicated by the file modification date. I need it to. A header file, the name of which is still in the makefile, has been removed because it is no longer needed. This is causing a an error and the project will no longer compile.
How are make files rebuilt?