[bug #63241] implement "exit" in makefile parsing

[anonymous]

URL:
  <https://savannah.gnu.org/bugs/?63241>

                 Summary: implement "exit" in makefile parsing
                 Project: make
               Submitter: None
               Submitted: Wed 19 Oct 2022 04:43:52 PM UTC
                Severity: 3 - Normal
              Item Group: Enhancement
                  Status: None
                 Privacy: Public
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any
       Component Version: SCM
        Operating System: None
           Fixed Release: None
           Triage Status: None


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Follow-up Comments:


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Date: Wed 19 Oct 2022 04:43:52 PM UTC By: Anonymous
I’ll start this by making an analogy with scripting languages. A Python
script might have logic like:

while <condition1>:
    if <condition2>:
        # do thing A
    else: 
        # do thing B

Indenting can go to unlimited depths so most languages offer a short-circuit
which makes things more readable:

while <condition1>:
    if <condition2>:
        # do thing A
        continue

    # do thing B

Coming back to GNU make, I have quite a few complex (many hundreds of lines)
makefiles which require logic like this (greatly simplified):

ifneq ($(filter %clean clobber,$(MAKECMDGOALS)),)
  <clean targets>
else
  <real targets>
endif

This makes it harder to read, because all the “real” logic is a subclause
(or 2, or 3) deep. Tracking if-else-endif across large files is difficult.
I’m wondering if the make parser would be capable of something like this:

ifneq ($(filter %clean clobber,$(MAKECMDGOALS)),)
  <clean targets>
  exit
endif
<real targets>

Where the “exit” keyword simply says to stop parsing. Perhaps there’s a
better name, but the basic idea is to implement short-circuit parsing
analogously to the shell example. Doable?








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