broken build environment - explanation and fix

[Bruno Haible]

Hi,

Today, I was stuck for a while with a broken build environment: Even after
doing "make distclean", then bootstrap, then a fresh build, the build stopped
with this error:

make[3]: Entering directory '/media/develdata/devel/POKE/poke/libpoke'
/bin/bash ../libtool  --tag=CC   --mode=compile gcc -ftrapv -DHAVE_CONFIG_H -I. 
-I../poke  -I../gl-libpoke -I../gl-libpoke -I../common -DPKL_DEBUG 
-DPKGINFODIR=\"/media/develdata/devel/inst-x86_64-64/share/info\" 
-DLOCALEDIR=\"/media/develdata/devel/inst-x86_64-64/share/locale\" 
-fvisibility=hidden -DBUILDING_LIBPOKE -DJITTER_DISPATCH_NO_THREADING=1 -I 
/media/develdata/devel/POKE/poke/jitter -I 
/media/develdata/devel/POKE/poke/jitter -I 
/media/develdata/devel/POKE/poke/jitter/machine/x86_64 -I 
/media/develdata/devel/inst-x86_64-64/include 
-I/media/develdata/devel/inst-x86_64-64/include -Wall -Wall 
-I/arch/x86_64-linux-gnu/gnu-inst-gc/8.0.6/include  -g -O2 -MT 
libpoke_la-pvm-program.lo -MD -MP -MF .deps/libpoke_la-pvm-program.Tpo -c -o 
libpoke_la-pvm-program.lo `test -f 'pvm-program.c' || echo './'`pvm-program.c
libtool: compile:  gcc -ftrapv -DHAVE_CONFIG_H -I. -I../poke -I../gl-libpoke 
-I../gl-libpoke -I../common -DPKL_DEBUG 
-DPKGINFODIR=\"/media/develdata/devel/inst-x86_64-64/share/info\" 
-DLOCALEDIR=\"/media/develdata/devel/inst-x86_64-64/share/locale\" 
-fvisibility=hidden -DBUILDING_LIBPOKE -DJITTER_DISPATCH_NO_THREADING=1 -I 
/media/develdata/devel/POKE/poke/jitter -I 
/media/develdata/devel/POKE/poke/jitter -I 
/media/develdata/devel/POKE/poke/jitter/machine/x86_64 -I 
/media/develdata/devel/inst-x86_64-64/include 
-I/media/develdata/devel/inst-x86_64-64/include -Wall -Wall 
-I/arch/x86_64-linux-gnu/gnu-inst-gc/8.0.6/include -g -O2 -MT 
libpoke_la-pvm-program.lo -MD -MP -MF .deps/libpoke_la-pvm-program.Tpo -c 
pvm-program.c  -fPIC -DPIC -o .libs/libpoke_la-pvm-program.o
pvm-program.c: In function 'pvm_program_parse_from_string':
pvm-program.c:366:7: error: void value not ignored as it ought to be
  366 |   err = pvm_parse_mutable_routine_from_string (str, program->routine);
      |       ^
pvm-program.c:369:41: error: invalid use of undefined type 'struct 
pvm_routine_parse_error'
  369 |       char *invalid_token = xstrdup (err->error_token_text);
      |                                         ^~
pvm-program.c:370:7: warning: implicit declaration of function 
'pvm_routine_parse_error_destroy'; did you mean 
'jitter_routine_parse_error_destroy'? [-Wimplicit-function-declaration]
  370 |       pvm_routine_parse_error_destroy (err);
      |       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      |       jitter_routine_parse_error_destroy
make[3]: *** [Makefile:3017: libpoke_la-pvm-program.lo] Error 1

A "make maintainer-clean" step then fixed the issue. Why? The three files
libpoke/pvm-vm.h, libpoke/pvm-vm1.c, libpoke/pvm-vm2.c were out of date.
The Makefile did not rebuild these files, because their time stamps were
in the right order:
  pvm.jitter <= pvm-vm.h <= pvm-vm1.c <= pvm-vm2.c

$ ls -l --full-time pvm.jitter pvm-vm.h pvm-vm1.c pvm-vm2.c
-rw-rw-r-- 1 bruno bruno  188225 2023-02-18 17:42:16.742881188 +0100 pvm.jitter
-rw-rw-r-- 1 bruno bruno  708623 2023-02-18 17:57:33.705849628 +0100 pvm-vm1.c
-rw-rw-r-- 1 bruno bruno 4920902 2023-02-18 17:57:33.745849492 +0100 pvm-vm2.c
-rw-rw-r-- 1 bruno bruno  166074 2023-02-18 17:57:33.705849628 +0100 pvm-vm.h

What was the problem then? I had
  1. done a "git pull" in poke,
  2. done a "git checkout master && git pull" in jitter,
  3. done a build (bootstrap --no-git && configure && make), which failed but
     generated libpoke/pvm-vm.h, libpoke/pvm-vm1.c, libpoke/pvm-vm2.c.
  4. done a build with the correct jitter version this time
     (make distclean, then bootstrap && configure && make)
but in step 4 the broken libpoke/pvm-vm.h, libpoke/pvm-vm1.c, libpoke/pvm-vm2.c
persisted there.

I see two possible fixes:
  A) erase libpoke/pvm-vm.h, libpoke/pvm-vm1.c, libpoke/pvm-vm2.c already
     during "make distclean", not "make maintainer-clean".
  B) add a dependency, to make sure that these files get rebuilt when jitter
     is rebuilt.

(B) seems more correct to me, so here's a proposed fix in that direction.

0001-build-Regenerate-pvm-vm.h-pvm-vm1.c-pvm-vm2.c-when-j.patch
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