[bug #48643] Irrelevant targets can confuse make on which pattern rule to select.

[anonymous]

URL:
  <http://savannah.gnu.org/bugs/?48643>

                 Summary: Irrelevant targets can confuse make on which pattern
rule to select.
                 Project: make
            Submitted by: None
            Submitted on: Wed 27 Jul 2016 05:02:12 AM UTC
                Severity: 3 - Normal
              Item Group: Bug
                  Status: None
                 Privacy: Public
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any
       Component Version: 4.2.1
        Operating System: POSIX-Based
           Fixed Release: None
           Triage Status: None

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Details:

This is a based on
https://lists.gnu.org/archive/html/help-make/2016-01/msg00011.html which I
couldn't find an actual bug report for.

I'm not 100% certain that this is a bug; it's possible that we're missing
something subtle in the manual, but I really do think it's a bug.

I've attached a test case.  The bad behavior is triggered by the last line in
the Makefile; commenting it out causes things to work correctly.

The correct graph for make to choose is


default -> a.foo (%.foo, line 3) -> a.correct -> a.correct_src


But, if we append this line, then make makes the wrong decision:


misleading_target: a.mislead


The line should be irrelevant, because misleading_target isn't something we're
trying to build.  But, it causes make to instead choose this graph:


default -> a.foo (%.foo, line 6) -> a.mislead -> a.mislead_src


That is, it chose the wrong pattern rule for %.foo .



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File Attachments:


-------------------------------------------------------
Date: Wed 27 Jul 2016 05:02:12 AM UTC  Name: Makefile  Size: 543B   By: None

<http://savannah.gnu.org/bugs/download.php?file_id=38033>

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