Flavor Function (GNU make)

From Get docs
Make/docs/latest/Flavor-Function


8.11 The flavor Function

The flavor function, like the origin function, does not operate on the values of variables but rather it tells you something about a variable. Specifically, it tells you the flavor of a variable (see The Two Flavors of Variables).

The syntax of the flavor function is:

$(flavor variable)

Note that variable is the name of a variable to inquire about, not a reference to that variable. Therefore you would not normally use a ‘$’ or parentheses when writing it. (You can, however, use a variable reference in the name if you want the name not to be a constant.)

The result of this function is a string that identifies the flavor of the variable variable:

undefined
if variable was never defined.
recursive
if variable is a recursively expanded variable.
simple
if variable is a simply expanded variable.