[bug #63098] make-4.3.90 regression of unexpected dependencies in pattern rules with multiple targets

[Sergei Trofimovich]

URL:
  <https://savannah.gnu.org/bugs/?63098>

                 Summary: make-4.3.90 regression of unexpected dependencies in
pattern rules with multiple targets
                 Project: make
               Submitter: slyfox
               Submitted: Fri 23 Sep 2022 07:05:25 PM UTC
                Severity: 3 - Normal
              Item Group: None
                  Status: None
                 Privacy: Public
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any
       Component Version: None
        Operating System: None
           Fixed Release: None
           Triage Status: None


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Follow-up Comments:


-------------------------------------------------------
Date: Fri 23 Sep 2022 07:05:25 PM UTC By: Sergei Trofimovich <slyfox>
Initially noticed the problem in OpenSP-1.5.2 build failure. Here is a
minimised example:


# cat Makefile
all: foo.a foo.b

%.a %.b %.c: %.d
        touch $*.a
        touch $*.b
        touch $*.c


To trigger it we need to have up-to-date foo.d, foo.a and foo.b:


$ touch foo.d; touch foo.a; touch foo.b

# good make-4.3:
$ make-4.3
make: Nothing to be done for 'all'.

# problematic make-4.3.90:
$ make-4.3.90
touch foo.a
touch foo.b
touch foo.c


Note how new make version decided it needs to do extra work.

Looks like a bug.

A bit of background on original bug context (in case I extracted it
incorrectly):

OpenSP-1.5.2 uses similar pattern in
https://sourceforge.net/p/openjade/code/HEAD/tree/trunk/sp/lib/Makefile.am


# ...
%.h %.cxx %.rc: %.msg
        [ ! -f $(top_srcdir)/msggen.pl ] || $(PERL) -w $(top_srcdir)/msggen.pl
$(MSGGENFLAGS) $<


OpenSP's release tarball ships only .h and .rc files (but not .cxx):
lib/WinInetStorageMessages.h lib/WinInetStorageMessages.msg
lib/WinInetStorageMessages.rc. It looks like nothing requires .cxx files in
that directory.

I only noticed the failure because my sandbox environment did not have perl
and caused build failure of make upgrade to 4.3.90.







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