RE: [bug #17529] Variable set with $(shell date '+%Y%m%d-%H%M%S') changes mid-make

[Martin Dorey]

> all variables are expanded exactly once - whether they are immediate
or
> deferred

No.  It might sound like that but that's definitely, definitely,
definitely not what happens.  Deferred variables are expanded again
every time they're used.  I thought perhaps I'd quoted the wrong part of
the documentation because, reading it again, I think you're right that
it isn't clear.  Searching for "deferred" didn't find me any other,
clearer part.  Perhaps a clarification patch would be in order.

Try the := idea.  I bet you can't break it.  Another idea that might be
more convincing:

base = $(shell date --iso=ns 1>&2)

That sends the output of date(1) to stderr, where you'll see it
directly, once for each time it's invoked.
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Martin's Outlook, BlueArc Engineering