CODEWITHSUNDEEP
makefile
Miro Kropacek
Miro Kropacek

Reputation: 2886

Is this a make bug?

Most likely it is not but I've been struggling with this one for an hour now:

$ cat Makefile
${FILE1}:
        touch $@

a: ${FILE1}

${FILE2}: a
        touch $@

$ make FILE1=foo FILE2=bar bar
touch foo
touch bar

$ ls
bar  foo  Makefile

$ make FILE1=foo FILE2=bar bar
touch bar

Why is the bar rule still activated?

If I change Makefile to:

${FILE1}:
        touch $@

${FILE2}: ${FILE1}
        touch $@

Everything works, i.e. bar is not touched again.

Upvotes: 1

Views: 36

Answers (1)

Beta
Beta

Reputation: 99124

The target bar has a prerequisite, a. You have a rule for a, but it does not actually build a file named "a". So every time you ask Make to rebuild bar (if necessary), Make sees that the prerequisite a does not exist, and therefore it must attempt to rebuild both targets.

Upvotes: 1

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