Re: make: warn/error on expanding undefined vars?

[christos%astron.com@localhost (Christos Zoulas)]

In article <20170310093510.GI4373%trav.math.uni-bonn.de@localhost>,
Edgar Fuß  <ef%math.uni-bonn.de@localhost> wrote:
>Is there a way to make make error out (or at least emit a warning) if an 
>undefined variable is expanded (where, of course, defined() and maybe 
>empty() and :U don't count as an expansion)?
>
>It took me hours yesterday to find out that a weird problem stemmed from an 
>undefined variable. And it was not a spelling error as usual, but me not 
>noticing the the assignment was resinding inside a conditional that was false.
>
>I'm afraid the answer is no because it's difficult to pin down what counts 
>as an expansion (i.e., assignment to another variable).

That used to be the original behavior...

christos