On Mon, 2016-11-07 at 12:46 -0500, Jeff King wrote: > Specifically I wanted to make sure that > > FOO = bar > FOO = > ifdef FOO > ... something ... > endif > > works as if FOO had never been set in the first place. Which it seems > to, at least in GNU make (and that is the only one we support, for > other reasons).
Yes, it will work. Confusingly, "ifdef" actually tests whether the variable has a non-empty value, not whether it's defined: > The 'ifdef' form takes the _name_ of a variable as its argument, not > a reference to a variable. The value of that variable has a non- > empty value, the TEXT-IF-TRUE is effective; otherwise, the TEXT-IF- > FALSE, if any, is effective *sigh* History...
