[Scons-users] How to debug problems?

[Mats Wichmann]

Folks, I'm just going insane with errors popping up... I've been trying
to do a weekly push to Coverity for static checking, and this has failed
today.

On restarting the build with some debug options added, it doesn't fail,
but I get some new surprising commentary. ??? if it fails, it should
keep failing, no?

Yeah, the rules to generate a .dat file are relatively new and clearly
they're causing some problems (before, people who made changes to the
json files they come from were supposed to regen and check in the .dat
file, and they always forgot to do so, so someone added a builder).  But
in the dep cycle complaints, it's not just .dat files, and that
complaint is only for one of a number of such files. But I can't see
what is wrong with that builder, and other people doing builds don't
seem to be running into this fail. Which is even more of a head-scratcher.

So I'm looking for advice on how you debug when running into these kinds
of outputs. For once I'm not finding stackexchange useful, it seems to
point to old information that "has been fixed" (e.g.
http://scons.tigris.org/issues/show_bug.cgi?id=2116), running 2.5.1 here.

Thanks for any debugging best-practices!


Initial run, normal options I've used several times before:
===

scons: *** Found dependency cycle(s):
  Internal Error: no cycle found for node
out/linux/x86_64/debug/resource/IPCA/samples/ElevatorServer/ElevatorServerSecurityDB.dat
(<SCons.Node.FS.File object at 0x3ae4ff04a0>) in state pending
  Internal Error: no cycle found for node
out/linux/x86_64/debug/java/base/objs (<SCons.Node.FS.File object at
0x3ae51a6eb0>) in state pending
  Internal Error: no cycle found for node
out/linux/x86_64/debug/java/examples-java/simpleclient/jar
(<SCons.Node.FS.File object at 0x3ae51e3fe0>) in state pending

===
Restart, adding "--debug=duplicate,explain,prepare":
===

...

BUILD SUCCESSFUL

Total time: 2.527 secs
scons: Cannot explain why
`java/examples-java/simpleserver/build/libs/oic_svr_db_server.dat' is
being rebuilt: No previous build information found
Preparing target
java/examples-java/simpleserver/build/libs/oic_svr_db_server.dat...
dup: removing existing target
java/examples-java/simpleserver/build/libs/oic_svr_db_server.dat
scons: Cannot explain why
`java/examples-java/simpleclientserver/build/libs/oic_svr_db_server.dat'
is being rebuilt: No previous build information found
Install file:
"java/examples-java/simpleserver/src/main/assets/oic_svr_db_server.dat"
as "java/examples-java/simpleserver/build/libs/oic_svr_db_server.dat"
Preparing target
java/examples-java/simpleclientserver/build/libs/oic_svr_db_server.dat...
dup: removing existing target
java/examples-java/simpleclientserver/build/libs/oic_svr_db_server.dat
Preparing target out/linux/x86_64/debug/java/examples-java/simpleclient...
Install file:
"java/examples-java/simpleserver/src/main/assets/oic_svr_db_server.dat"
as "java/examples-java/simpleclientserver/build/libs/oic_svr_db_server.dat"