Suggestion for make manual

[Sean Mahnken]

I came across a peculiar behavior while working with make.  If it is expected behavior, it would be worth documenting.  If it is not, a bug should be filed.

 

The following variable will never receive its default assignment:

 

# Set default for foo

export foo

foo ?= 5

 

 

It would appear that the export directive causes variables to be defined with an empty value, which renders the ?= assignment useless.  However, the following works fine:

 

# Set default for foo

export foo ?= 5

 

This may be common knowledge for some folks, but I struggled with it for a while.  I believe it would be worth noting in section 5.7.2 and/or 6.2 of the make manual.

 

Thanks –

Sean Mahnken