Hi, Sorry, I didn't see your message earlier because I'm not on the list and it didn't email me.
This seems to work fine, as long as I also define a rule for the build directory itself, since the % can't match an empty string. It doesn't work in make 3.81 -- there, make seems to ignore the trailing slash in the prerequisite. As a workaround I can write '$$(@D)/.' (trailing dot) and it works fine. Anyway thanks, this is good enough for me. Thanks, Ismail Ismail Badawi wrote: > > >* I'm trying to define new targets with eval during secondary expansion, but* > >* apparently this is not allowed -- with make 4.2.1 I get an error like* > >* this:* > > > >* Makefile:94: *** prerequisites cannot be defined in recipes. Stop.* > > > >* I found bugs #24588 and #24622 related to this.* > > > >* My use case is as follows. I have a bunch of targets which can be nested* > >* arbitrarily deeply in subdirectories within my build directory. For each* > >* target, I'd like to have an order-only prerequisite on the existence of* > >* its parent directory. So something like this:* > > > >* build/foo/bar/baz/mytarget: | build/foo/bar/baz* > >* touch $@* > > > >* build/foo/bar/baz:* > >* mkdir -p $@* > > > >* The issue is that if I have many targets in many different directories,* > >* then I* > >* need to write lots of 'mkdir' rules like this. I can save some typing with* > >* a template and a foreach/eval/call, but that's still a bit awkward because* > >* I have* > >* to maintain a list of all the directories I need.* > > I don't have a solution to your general problem but for your specific > requirement of creating directories this is what I do: > > 1. All directories must end in the '/' character. > > 2. Use secondary expansion to determine the target directory. Note trailing > '/'. > > build/foo/bar/baz/mytarget: | $$(@D))/ > touch '$(@)' > > 3. Define pattern rule for directories. > > $(build_dir)%/ : > mkdir -p '$(@)' > > 4. You may need to mark the pattern as precious > > .PRECIOUS : $(build_dir)%/ > > Works well for me for 4.1 and later. No need to list directories. Only one > rule required. > > -- > JP > >
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