How to match double stem in target like %/% or other way? - makefile

Question

I need to build targets with names like,
v1/thread4/foo v1/thread8/foo v1/thread16/foo
v2/thread4/foo v2/thread8/foo v2/thread16/foo
I want to match the thread% and v%, because for my code, the threadNum=? and the Version=? are the Macros need to define in the compile time.
so in the result, I hope to get a layout like, and the foo is the executable name
v1-|thead4/foo
|thead8/foo
|thead16/foo
v2-|thead4/foo
|thead8/foo
|thead16/foo
I've tried ways like, it doesn't work
%/%/foo: foo.cc $(HEADERS)
$(CXX) $(CXXFLAGS) -DTHREAD=$* -o $# $< $(LDLIBS)

Answer 1

It's pretty easy when you realise that $# is v1/thread4/foo (say),
to then pull out the bits you need.
In this case, something like:
v = $(firstword $(subst /, ,$#))
thread = $(notdir ${#D})
YMMV of course. leading to
targets := \
v1/thread4/foo v1/thread8/foo v1/thread16/foo \
v2/thread4/foo v2/thread8/foo v2/thread16/foo
all: ${targets}
v = $(firstword $(subst /, ,$#))
thread = $(notdir ${#D})
${targets}:
: '$#: v [$v] thread [${thread}]'
giving
$ make
: 'v1/thread4/foo: v [v1] thread [thread4]'
: 'v1/thread8/foo: v [v1] thread [thread8]'
: 'v1/thread16/foo: v [v1] thread [thread16]'
: 'v2/thread4/foo: v [v2] thread [thread4]'
: 'v2/thread8/foo: v [v2] thread [thread8]'
: 'v2/thread16/foo: v [v2] thread [thread16]'

Answer 2

There is no way to have multiple patterns in GNU make.
If your example above is actually reflective of what you want to do, it's simple enough, though:
VLIST := 1 2
TLIST := 4 8 16
TARGETS := $(foreach V,$(VLIST),$(foreach T,$(TLIST),v$V/thread$T/foo))
$(TARGETS): foo.cc $(HEADERS)
$(CXX) $(CXXFLAGS) -DTHREAD=$* -o $# $< $(LDLIBS)