RE: Silently ignored command line options when assigned (not overrided) in makefile

[Rakesh Sharma]

Hi David,

The best way to deal with this particular scenario in GNU make (IMHO) is via 
the use
of the $(origin ..) & the $(error ..) functions, like as:


Makefile:

NULL :=
SP := $(NULL) $(NULL)

# $(call bad_var,variablename)
bad_var = $(error The variable '$1' cannot be declared on the command line)

$(if $(filter-out commandline,$(subst $(SP),$(NULL),$(origin A))),,$(call 
bad_var,A))

# **** your make code below this ***


> From: address@hidden
> Date: Wed, 25 Jun 2014 22:09:47 +0200
> Subject: Re: Silently ignored command line options when assigned (not 
> overrided) in makefile
> To: address@hidden
> CC: address@hidden
> 
> Hi Paul,
> 
> I have some variables inside makefile without override directive. When
> someone assigns it via command line (or in recursive make rule) rule set by
> user is ignored. I want to detect if someone uses cmd line assignments and
> warns about that this is forbidden.
> 
> Example:
> 
> Makefile:
> 
> test: A=1
> test:
>       @echo "A="$(A)
> 
> cmd line:
> make -f Makefile test (no warning)
> make -f Makefile test A=2 (warning)
> 
> One of method is to use "ifdef" test to check before assignment in makefile
> if variable was already set and print warning about that. But I am curious
> if there is any other method, some makefile flag or something ?
> 
> Br
> Dawid
> 
> 
> 2014-06-24 18:53 GMT+02:00 Paul Smith <address@hidden>:
> 
> > On Tue, 2014-06-24 at 12:14 +0200, Dawid Gosławski wrote:
> > > It's not a bug, it's planned and documented. However I want to know how
> > to
> > > give users some warning about that assignment ? Of course we can declare
> > > something like that:
> > >
> > > ifdef CFLAGS
> > > $(warning "CAN NOT OVERRIDE CFLAGS BY COMMAND LINE")
> > > endif
> > >
> > > on the beginning of the makefile but is there any better option for that
> > ?
> > > With multilevel structure and a lot of variables that potentially coult
> > be
> > > overrided make should give any warning when not assigning values as uses
> > > assumes.
> >
> > Hi Dawid.  I'm afraid I'm not quite able to follow the situation.
> >
> > A command-line setting of a variable will always take precedence over an
> > assignment of that variable in the makefile, unless the makefile
> > assignment uses the "override" directive.
> >
> > Are you saying that this is not working for you?
> >
> > Or are you saying you do not want to allow variables to be overridden in
> > your environment?
> >
> > Or do you want to warn users if they do override these variables when
> > they shouldn't?
> >
> > Or warn them if they do not override them when they should?
> >
> >
> 
> 
> -- 
> http://about.me/alkuzad
> _______________________________________________
> Help-make mailing list
> address@hidden
> https://lists.gnu.org/mailman/listinfo/help-make