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Re: include and reparsing Makefile
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From: |
Paul Smith |
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Subject: |
Re: include and reparsing Makefile |
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Date: |
Wed, 17 Apr 2013 06:50:43 -0400 |
On Wed, 2013-04-17 at 06:18 +0000, Warlich, Christof wrote:
> nothing:
> reparse.mk: mayOrMayNotExist ; @echo would remake $@
> -include reparse.mk
>
> When I call make while the file mayOrMayNotExist does exist, I get:
>
> $ touch mayOrMayNotExist
> $ make
> would remake reparse.mk
> make: Nothing to be done for `nothing'
>
> But when the file mayOrMayNotExist does _not_ exist, I only get
>
> $ rm -f mayOrMayNotExist
> $ make
> make: Nothing to be done for `nothing'.
If mayOrMayNotExist exists then make has a rule that knows how to build
reparse.mk. Since mayOrMayNotExist is newer than reparse.mk (you just
touched it), make will run the rule then re-exec itself.
It's not clear from your message whether you understand that part; if
not see the GNU make manual section "How Makefiles are Remade".
If mayOrMayNotExist does not exist then the rule to remake reparse.mk
fails because the prerequisite does not exist and make doesn't know how
to create it.
However, because you requested the "-include" form, rather than just
"include", the normal error message is suppressed and the build proceeds
without any message.