Re: GNU make release candidate 3.99.90 available

On 05/17/13 01:12, Paul Smith wrote:
> Hi all.  The first release candidate for the next release of GNU make,
> GNU make 4.0, is now available for download:
>

Hi Paul,

This announcement shocked me out of complacency.
Is there any chance I could slip-in a feature at this very late date?
If not, I understand.  When might you make a new release?

The feature is something we discussed many years ago, but I dropped
it because I was preempted by paid work and because I had an ugly
work-around.

The problem surfaces with programs that generate multiple output
files combined with parallelism via -jN. An obvious example is
yacc/bison, for which there is already aspecial-case pattern-rule.
I need to solve the general case, whereoutput filenames don't
fit into the naming pattern required bythe yacc/bison mechanism.

We had discussed syntax like so:

[a b c d]: e f
         generate $<

I'm going to implement this over the weekend, and cross my fingers
that you might be able to slip it in.

G

PS: Here's my kludgy work-around:

### Function: $(call 
generate-many,1=STAMP_FILE_NAME,2=GENERATED_FILE_NAMES,3=SOURCE_FILE_NAMES)
###
### Remove a stamp file if any of its prerequisite generated files are absent

define generate-many
   ifneq (,$$(wildcard $(1)))
     ifneq (,$$(filter-out $$(wildcard $(2)),$(2)))
       $$(warning Removing $(1) because of missing files: \
          $$(call nl-ht,$$(filter-out $$(wildcard $(2)),$(2))))
       dummy := $$(shell $$(RM) $(1))
     endif
   endif
   $(filter-out $(1),$(2)): $(1)
   $(1): $(3) | $(call dir-chop/,$(1))
endef

Deployed like so:

$(eval $(call generate-many,gen-stamp,a b c d,e f))
gen-stamp:
         $(TOUCH) $@-$(pid)
         generate e f
         $(MV) $@-$(pid) $@

In case you want to actually test the above, here's the infrastructure
required:

empty :=
space := $(empty) $(empty)
tab := $(empty)    $(empty)
, := ,
### There MUST be TWO newlines below for $(newline) to expand to a single 
newline
define newline


endef

nl-ht =        $(newline)$(tab)$(subst $(space),$(newline)$(tab),$(strip $(1)))

chop/ =        $(patsubst %/,%,$(1))
dir-chop/ =    $(call chop/,$(dir $(1)))

pid :=        $(shell echo $$PPID)