"Paul Smith via austin-group-l at The Open Group"
<austin-group-l@opengroup.org> wrote:
> But here we're inventing an entirely new operator that NO VERSION of
> make currently implements (yes, I understand that BSD make has a
> different operator that works in this same way but that's not the same
> thing: no existing makefile today contains the :::= operator so every
> makefile that wants to use it will have to be changed, and in a way
> which is not backward-compatible with older versions of make).
You are mistaken.
The :::= operator has been implemented in two independent make programs before
it was standardized.
The :::= operator was introduced to smake and SunPro Make in March. At that
time it did use the same behavior as smake and BSD make implemented the :=
operator since 30 years.
While diskussing that operator in the teleconference, we discovered that BSD
make added .MAKE.SAVE_DOLLARS three years ago to deal with corner cases. We
asked the BSD developers for their preference on whether $$ expansion should
be disabled by default in case that a new operator was introduced that does
not need to implement compatibility with the 30 year old := from BSD make and
smake.
As a result of that, we decided that not expanding $$ is the right way to go
and that behavior was implemented for :::= in smake and SunPro Make. The
behavior was tested with the makefiles we developed before and a week after
smake and SunPro Make introduced the complete behavior for :::=, the new POSIX
feature was decided on and the current text was written.
So this is not invention but developing a new operator based on experiences
with existing make implementations and soon after deciding on the standard.
If you like to test :::=, just compile a recent schilytools version and check
smake and SunPro Make.
The support for the accepted behavior was first published in the 2021-08-14
version. The finally accepted POSIX text is from 2021-08-16.
Jörg
--
EMail:jo...@schily.net Jörg Schilling D-13353 Berlin
Blog: http://schily.blogspot.com/
URL: http://cdrecord.org/private/
http://sourceforge.net/projects/schilytools/files/
