Fix MAKEFLAGS parsing with Make 4.4+

[minijackson]

Since Make version 4.4, MAKEFLAGS also contains long options and overridden variables on the command-line (source).

This means that parsing by filtering out --% doesn't work reliably anymore, since it doesn't remove overrides:

Running make VAR=quacks gives MAKEFLAGS=" -- VAR=quacks", and checkflags would understand that flags -q, -s, ... were set.

This would get transmitted below into QUIET_FLAGS and QUESTION_FLAG, then passed to the genVersionHeader.pl as -i and -q.

The result would be that genVersionHeader.pl would never create the version header (only check for its up-to-date status), leading to confusing errors:

  ../misc/epicsRelease.c:25:32: error: expected ')' before 'EPICS_VCS_VERSION'
     25 |     printf ( "## %s\n", "Rev. " EPICS_VCS_VERSION );
        |            ~                   ^~~~~~~~~~~~~~~~~~

The NEWS file recommends using firstword, so we can use just that.

[mdavidsaver]

A good catch.

Do you (and @anjohnson) think any of the other WARNING: Backward-incompatibility! items in the linked NEWS file will effect us?

At a glance, I think not. With the possible exception of the change to $(shell and exported environment.

[simon-ess]

Unless I'm misunderstanding something, this no longer does the same thing for older versions of make: If I run make with a mix of flags (say -q -n --no-print-directory) then I see the following sort of output:

$(info ${MAKEFLAGS})
$(info $(filter-out --%,$(MAKEFLAGS)))
$(info $(firstword $(MAKEFLAGS)))

yielding

 --no-print-directory -sqn
-sqn
--no-print-directory

as such the change you propose seems to break things for at least make 3.82

[minijackson]

@simon-ess aahhh, there goes my simple fix...

You're right, the NEWS file mention that the MAKEFLAGS variable is rigorous only from GNUMake 4.0+ (here)

For a quick check I did:

make -p -q -s --no-print-directory -j4 A=4 | grep MAKEFLAGS

yields for make 4.4.1:

MAKEFLAGS = pqs -j4 --jobserver-auth=fifo:/tmp/GMfifo130336 --no-print-directory -- $(MAKEOVERRIDES)

and for make 3.82:

MAKEFLAGS =  --no-print-directory -sqp --jobserver-fds=3,4 -j -- $(MAKEOVERRIDES)

---

Is there any possibility of removing this parsing as a whole?

[anjohnson]

There are discussions about testing MAKEFLAGS in the answers to this question on Stack Overflow, but they probably all pre-date 4.4; My answer describes the solution that's currently in Base and mentions the subtle difference between its in-recipe and outside values. Could someone please try using the test Makefile in my answer on Make 4.4 to confirm that it does get false results.

@simon-ess The NEWS file recommends using $(firstword -$(MAKEFLAGS)) which isn't quite what you tested above (you missed the - sign), although I don't see that it would make any significant difference.

If necessary we might be able to add a version check to continue to support older versions, note that Apple continues to ship GNU Make version 3.81 with MacOS and/or XCode. Later versions were released under the GPLv3 which they will not accept.

I don't want to remove these checks, they are too useful.

I didn't see anything obvious in the NEWS incompatibility descriptions, hopefully this is the only thing that we will have to resolve.

[minijackson]

@anjohnson checking your test Makefile:

define checkflags
  make-$1 = $(findstring $1,$(filter-out --%,$(MAKEFLAGS)))
endef
$(foreach flag,i r w s k n q, $(eval $(call checkflags,$(flag))))

$(info MAKEFLAGS = "$(MAKEFLAGS)")
$(foreach flag,i r w s k n q, \
    $(info make-$(flag) = "$(make-$(flag))" $(if $(make-$(flag)),YES,NO)))

all:
    @+echo 'all: MAKEFLAGS = "$(MAKEFLAGS)"'
    @+echo 'all: $(foreach f,i r w s k n q,$(make-$f))'
    @+echo ''

And running make A=irwsknq

with GNUMake 4.4.1:

MAKEFLAGS = " -- A=irwsknq"
make-i = "i" YES
make-r = "r" YES
make-w = "w" YES
make-s = "s" YES
make-k = "k" YES
make-n = "n" YES
make-q = "q" YES
Makefile:13: *** missing separator.  Stop.

With GNUMake 4.3:

MAKEFLAGS = ""
make-i = "" NO
make-r = "" NO
make-w = "" NO
make-s = "" NO
make-k = "" NO
make-n = "" NO
make-q = "" NO
Makefile:13: *** missing separator.  Stop.

GNUMake 3.82 has the same result as 4.3.

[anjohnson]

This version of checkflags seems to work for me on both 3.81 and 4.4.1:

makeflags := $(firstword $(filter-out -,$(filter-out --%,$(MAKEFLAGS))))
define checkflags
    make-$1 := $(findstring $1,$(makeflags))
endef

3.81 seems to insert the odd - word into MAKEFLAGS, but this combination of filters left just the single letter options in the first word in all my tests.

@minijackson Please adjust your PR and test this.

[AppVeyorBot]

✅ Build EPICS Base 7 base-7.0-948 completed (commit a0948ca2d9 by @minijackson)

[minijackson]

@anjohnson done, sorry for the delay.

Tested by compiling EPICS with GNUMake 4.4 and 4.3. Compiling with Make 3.82 is a bit harder for me, I don't know if someone (@simon-ess?) can test it?

[AppVeyorBot]

❌ Build EPICS Base 7 base-7.0-963 failed (commit 0bca15d16b by @minijackson)

[AppVeyorBot]

✅ Build EPICS Base 7 base-7.0-963 completed (commit 0bca15d16b by @minijackson)

[simon-ess]

The current version behaves as expected for GNUMake 3.82.

[anjohnson]

Thanks @simon-ess, this looks good now.

[mdavidsaver]

Applied as d87fd0d