Re: make :Q breakage

[Valery Ushakov <uwe%stderr.spb.ru@localhost>]

On Sat, May 26, 2018 at 11:59:27 -0400, Christos Zoulas wrote:

> On May 26,  6:25pm, uwe%stderr.spb.ru@localhost (Valery Ushakov) wrote:
> -- Subject: Re: make :Q breakage
> 
> | :Q is defined to quote *shell* meta-characters.  The problem with $$
> | $$$$ $$$$$$$$ etc is not unique to make but is endemic to all
> | macro-processors in some form.  At least make does recursive
> | expansion, so you mostly (only?) run into this with submakes.
> | 
> | As far as I understand you don't really need a new modifier, as
> | existing :S should do:
> | 
> |     DOLLAR=$$
> |     ...
> |         make DOLLAR=${DOLLAR:S/\$/&&/g:Q}
> | 
> | When a variable is expanded, the only remaining '$' characters in it
> | are from $$ in the original, since you know you are passing this to
> | another make you use :S to double them again for the nested make.  And
> | shell-quote the result with :Q
> | 
> | E.g.
> | 
> | # ---8<--- d.mk ---8<---
> | PID=$$$$
> | .if !defined(NESTED)
> | all:
> | 	echo ${PID}
> | 	echo ${PID:Q}
> | 	make -f d.mk NESTED=${PID:S/\$/&&/g:Q}
> | .else
> | all:
> | 	echo ${NESTED}
> | 	echo ${NESTED:Q}
> | .endif
> | # ---8<---
> | 
> | 
> | If you want to hide the gory details you can probably even do
> | something like
> | 
> | MAKEQUOTE=S/\$$/&&/g:Q
> | ...
> | 	make .... NESTED=${PID:${MAKEQUOTE}}
> 
> This is still ugly. When would you *not* want :Q to do this automatically?

When you want to pass e.g. variable reference to be interpreted by the
submake?  I.e.

# FOO and BAR are defined in the submake, you can select which one you
# want to use
#DEFVAR=$${FOO}
DEFVAR=$${BAR}

	make -f other.mk VAR=${DEFVAR:Q}

Which is like setting VAR=${BAR} in the submake.  You want :Q for the
shell, but you do mean to pass single $ here that you need to express
with $$ in the caller.

Actually, the variable can be a shell variable too and not necessarily
quoted to pass to a submake.  The use case your change broke with
pkgsrc tools is exactly that for shell's $@

-uwe