waf: Uselib options in custom rule

Question

I have a waf build script and need to invoke a program which is not officially supported.

#file wscript
def configure(conf):
  conf.env.LIB = ['c', 'd']
  conf.env.INCLUDES = ['include']
  conf.env.LIB_xml2 = ['xml2']
  conf.env.INCLUDES_xml2 = ['/usr/include/libxml2']

def build(bld):
  bld(rule="dstep ${SRC} -o ${TGT} ${LIB_ST:LIB} ${DINC_ST:INCLUDES}",
    use="xml2",
    source="header.h",
    target="target.d",
    )

This expands to dstep header.h -o target.d -lc -ld -I/usr/include/libxml2, so only the global LIB variable works, the use parameter seems to entirely ignored.

How can I make it respect the use parameter?

Answer 1

For waf to process the use keyword, you must add the use feature to your task generator. You also need to add a "compile" aware feature like c, d or cxx. Like this:

def build(bld):
  bld(
    rule="dstep ${SRC} -o ${TGT} ${LIB_ST:LIB} ${DINC_ST:INCLUDES}",
    features = ["use", "c"],
    use="xml2",
    source="header.h",
    target="target.d",
  )

You can also program specifics for your dstep (You have to define a dstep feature and define the USELIB_VARS["dstep"])

Note: See ccroot.py in waf code.