Created attachment 639492 [details, diff]
hplip's configure.in contains a Bashism (use of == operator with test built-in). Thus, configure emits an error when /bin/sh is not Bash. This doesn't cause the build to fail outright, but it may be causing misdetection of features.
test `sh ./createPPD.sh -q` == 0
./configure: 16844: test: g++: unexpected operator
Aside from the Bashism, there is also the issue that the output of the backticked command may split into some number of words other than one, so it should be double-quoted.
After those two corrections, it's still unclear what those lines in the configure script are even supposed to be doing since they're 'test' invocations whose exit status is promptly ignored. ::shrug::
The attached patch fixes up the syntax and allows net-print/hplip-3.20.3 to configure without error.
Should be fixed in Git with hplip-3.20.5.