GNU Makefile first target not getting invoked

Question

I am following the solution in GNU Makefile treating each recipe line as sub-shell command without continuation character

target_compile: PROJECT_SIM_OPTS += -LDFLAGS -L${CURRENT_DIR},-lm -load

target_compile: copy_shared_object actual_compile_with_sim_opts
    @echo PROJECT_SIM_OPTS=${PROJECT_SIM_OPTS} ...

When I make the Makefile, I am able to see the second target_compile fire off but not the first target_compile which has no dependencies and recipe except a variable. I tried adding override before PROJECT_SIM_OPTS and ; at the end of the line but still it is not working.

There is no Error message reported which makes it even harder to detect. In nutshell, I have to embed this piece of code in another Makefile and if the first target would work, I will see a file generated with -LDFLAGS -L${CURRENT_DIR},-lm -load in it. Since this file is being generated without these flags, I am confident to say that first target is not firing.

How can the two target_compile work together?

I cannot reproduce your error. I get PROJECT_SIM_OPTS=-LDFLAGS -L,-lm -load ... Can you confirm that you get PROJECT_SIM_OPTS= ...? Which version of Make are you using? — Beta
@Beta. Thanks for your comment. Here is what I see for Make version GNU Make 4.0 Built for x86_64-unknown-linux-gnu — tulamba
@Beta I confirm I see what you see. I am testing it in my actual makefile which takes 40 minutes to compile. — tulamba
Then comment out the time-consuming compiler command, and add an echo PROJECT_SIM_OPTS=${PROJECT_SIM_OPTS}. If that works, uncomment the compiler command but make sure the command itself is being echoed to the screen so that you can see what it actually is -- and interrupt the compilation, don't wait 40 minutes. — Beta
@Beta. I believe I have a clue. PROJECT_SIM_OPTS is a global variable earlier in an included makefile while in target_compile, which comes later, it is target specific variable. I see its value being printed in the file when PROJECT_SIM_OPTS is a global variable but not when it is target specific variable. Any idea how to make its behavior like a global variable even in a target scope? — tulamba

tulamba tulamba · Accepted Answer · 2018-04-04T14:12:01

It turned out to be an ordering issue. In my case

target_compile: copy_shared_object actual_compile_with_sim_opts
    @echo PROJECT_SIM_OPTS=${PROJECT_SIM_OPTS} ...

actual_compile_with_sim_opts was running before copy_shared_object

Once I put the dependency like this, actual_compile_with_sim_opts: copy_shared_object

I was able to get both targets to work with proper flags

Thanks @Beta for all the help.

GNU Makefile first target not getting invoked

1 Answers