Post 3.81 $? handling

[John Graham-Cumming]

The NEWS file for 3.81 states:

  Up to and including this release, the '$?' variable does not contain
  any prerequisite that does not exist, even though that prerequisite
  might have caused the target to rebuild.  Starting with the _next_
  release of GNU make, '$?' will contain all prerequisites that caused
  the target to be considered out of date.  See this Savannah bug:
  http://savannah.gnu.org/bugs/index.php?func=detailitem&item_id=16051

I've tried and failed to create an example that has a prerequisite that 
doesn't exist, yet runs.  For example, if I do:

    all: siegfriednroy
        @echo Newer prerequisites are $?

    siegfriednroy:

Then I get 'Newer prerequisites are siegfriednroy' on both GNU Make 3.80 
and 3.81.   I then tried:

    all: siegfriednroy
        @echo Newer prerequisites are $?

    .PHONY: siegfriednroy
    siegfriednroy:

And get the exact same result.  Naturally there is no file called 
'siegfriednroy' on my system.

Can someone provide an example of $? not containing a non-existent 
prerequisite? (All my testing was done on Linux)  Obviously if I just do:

    all: siegfriednroy
        @echo Newer prerequisites are $?

then GNU Make errors out because it can't find siegfriednroy.

John.
--
John Graham-Cumming
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