CODEWITHSUNDEEP
makefilegnu-make
vapace
vapace

Reputation: 350

How do I prefix a gmake variable

I have a Makefile that includes another makefile, say CommonMakefile. There is a variable that I want to prefix with a value (cf. appending using +=) keeping rest of the value intact. 

V = value1    # set in CommonMakefile that is included

V = value0 $(V)  # I want to prefix value0 to V

# rule defined in CommonMakefile that is included
whatsV:
     echo $V   # first char is a <TAB> here

How can I do that?

Expecting:

$ gmake whatsV
value0 value1

Actual:

$ gmake whatsV
Makefile:3: *** Recursive variable `V' references itself (eventually).  Stop.

PS: I can-not/do-not-want to change CommonMakefile.

Upvotes: 0

Views: 860

Answers (1)

Beta
Beta

Reputation: 99134

This won't work:

V = value0 $(V)

because here V is a recursively expanded variable, and it can't be defined in terms of itself. But change it to a simply expanded variable:

V := value0 $(V) # <-- Note the colon

and it will work as intended.

Upvotes: 1

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