Bug 13205

It's a bit unfortunate that Bitbake silently accepts lines like this:

> SRC_URI_append = "file://capture.sh"

when the user almost certainly should have typed:

> SRC_URI_append = " file://capture.sh"

In a similar vein, likes like this:

> RM_WORK_EXCLUDE += " rawv4l2cap"

are accepted, even though—in the vast majority of cases—they should read:

> RM_WORK_EXCLUDE += "rawv4l2cap"


Personally, I must have copy/pasted += assignments with [useless] extra whitespace at least a hundred times in the last five years. This anti-pattern is *everywhere* out there in the wild, and it makes the output from running `bitbake -e` inscrutable.

Bitbake should warn users when they misuse whitespace, perhaps with an override to silence the warning for those rare cases where the usage is legitimate/necessary. Although... I've not personally encountered a case where, say `FOO_append = ".sh"` couldn't be replaced with `FOO .= ".sh"`, so... perhaps it ought to be a warning for a few Bitbake versions, which eventually becomes a 'hard' error after the deprecation period is over.

Anyway, leveraging the tool itself to lint out this rampant anti-pattern may be the only practical way to grapple with it. If Bitbake continues permitting users to include extra whitespace—or omit it when it should be required—they'll just keep doing it, and posting recipes with 'bad' snippets that get copy/pasted around to other recipes, perpetuating the cycle.