top_builddir vs. builddir

[Пухальский Юрий Андреевич]

Good day!

As of autoconf 2.59, in toplevel Makefile @top_builddir@ appears to be empty, 
while @builddir@ is ".". While apparently $(top_builddir) is "." and 
$(builddir) is empty. In the documentation it is stated, that:

Variable: top_builddir 
The relative path to the top-level of the current build tree. In the top-level 
directory, this is the same as builddir.