Re: I need support with a planned POSIX make extension

[christos%astron.com@localhost (Christos Zoulas)]

In article <20210709154331.wDTSm%schily%schily.net@localhost>,
(Joerg Schilling)  <schily%schily.net@localhost> wrote:
>Hi, 
>
>I am currently trying to get an orthogonal extension into POSIX make in order 
>to have at least an orthogonal variant as a choice instead of the incompatible
>GNU make extensions called:
>
>	:= that has been standardized in POSIX as ::= and that creates a 
>	   different type of make macro with different behavior
>
>	+= from GNU make that is incompatible to the much older += from
>	   SunPro Make. The incompatibility is that if a make macro has been
>	   created by the GNU := (POSIX ::=) instead of the standard 
>	   assignment operaror =, += first expands the right side before 
>	   appending the expanded result to the macro.
>
>	The different type of macros created with the GNU := is not
>	expanded at use time.
>
>The incompatible behavior from GNU make has the following problems:
>
>1)	expansion always could be prevented in a standard compliant way
>	by using $$(MACRO), instead of using a different macro type.
>
>2)	large makefiles that make heavy use of the include directive 
>	become highly unpredictable because you cannot know what a +=
>	operator will do, since the first definition of the related make
>	macro is most likely in a different include file.
>
>	I already filed a bug against POSIX for that and POSIX now recommends
>	to include at least one lower case letter in the name of a make
>	macro created via GNU make := (POSIX ::=).
>
>3)	The GNU make documentation is written so badly that most people
>	who use := do not know that this causes unexpected behavior with
>	the += operator.
>
>In order to have at least the choice of an orthogonal way of doing what 
>people expect, I defined and implemented two new operators:
>
>	:::=	Assigns to a make macro by first expanding the right
>		side of the assignment, but without creating a different
>		type of make macro.
>
>	+:=	Appends to a make macro by first expanding the right
>		side of the assignment, regardless of the type of the
>		make macro that is to the left.
>
>and I filed a bug against POSIX to enhance the standard to include these
>new operators, see:
>
>	https://www.austingroupbugs.net/view.php?id=1471
>
>BTW: I am the author and maintainer of smake and I am the current maintainer
>of SunPro Make as well. Both programs are part of the schilytools package
>and already include support for the new operators.
>
>The time to implement the new operators was 1-4 hours for each of the make
>implementations, so this is a really cheap extension.
>
>Given that bmake otherwise behaves like smake for :=, I hope that *BSD could
>be willing to support my enhancement.
>
>So my question is: would you be willing to implement support for :::= and +:=
>into bmake and publish that will to the POSIX bug tracking system?

I don't see an issue implementing them, but it feels to me that we are
creating more of a mess this way, because very few people will understand
and know which operator to use when and why.

I wish I could propose some more meaningful syntax, but if we are going
to rely on just punctuation, I don't have any better ideas.

Best,

christos