Re: how to (correctly) modify GNU Make so that separate shell is always spawned for each command

[Mark Galeck]

Paul,
I guess you are saying that in fact the Make statement
export VAR-Y := val
(attempts to) establish a shell (environment) variable, and is not merely a 
Make construct. Is that what you are saying?
But if that is so, then, well, VAR-Y is a valid Make variable (because nothing 
says otherwise in the Make manual), but is not a valid shell variable, so the 
above construct might not work for GNU Make, period?
I thought the above statement must NOT involve  shell at all, precisely 
because, it is not a valid shell variable.  


Mark

      From: Paul Smith <address@hidden>
 To: Mark Galeck <address@hidden>; "address@hidden" <address@hidden> 
 Sent: Friday, April 15, 2016 9:57 PM
 Subject: Re: how to (correctly) modify GNU Make so that separate shell is 
always spawned for each command
   
On Sat, 2016-04-16 at 03:51 +0000, Mark Galeck wrote:
> The failure case is:
> Makefile:
> export VAR-Y := val
> .PHONY: all
> all:        $(MAKE) -f Makefile1
> 
> Makefile1:
> $(warning VAR-Y $(VAR-Y))
> all:
> 
> 
> Here, if I call 
> >make
> the original Make works correctly, the value is printed in Makefile1,
> but after the above modification, no value is printed (the value is
> empty).

Make isn't doing anything differently so it must be your shell.  Note
that if I modify Makefile to ensure make uses the slow path to invoke
the sub-make (by adding ":;" for example), I get the "correct" behavior
you report.  I can't get make to show the incorrect behavior you report
(although I've not tried to change the code).

Note that "VAR-Y" is not a valid environment variable name; shell
variables must match the regex [A-Za-z][A-Za-z0-9_]*.  It could be that
for some reason your shell is suppressing variables in the environment
which have illegal names, but only when you invoke it using your
changes.