[Scons-users] Unreliable build problem

Hill, Steve (FP COM) Steve.Hill at cobham.com
Fri Apr 21 03:19:36 EDT 2017

Hi Tom,

That is certainly a possibility - not a common thing to do which would also explain why it happens fairly infrequently. Did you find a way of detecting/policing this or was it simply a case of education?



From: Scons-users [mailto:scons-users-bounces at scons.org] On Behalf Of Tom Tanner
Sent: 20 April 2017 13:47
To: SCons users mailing list
Subject: Re: [Scons-users] Unreliable build problem

Is it possible people are reverting source files while doing the build? That caused us nightmares just like this.

On 20/4/17 11:06, Hill, Steve (FP COM) wrote:
Thanks for your response Bill.

We are running on Windows 7. The build where we usually see this is our unit-test build (where a bunch of C/C++ files are compiled and linked, after which the executable is run and the build only passes if the executable returns 0) but that is probably down to that build being the most common build and the one where devs are more likely to revert changes. It is the .c->.obj step that is causing the problem.

We have a couple of hundred developers building using SCons and this happens once every month or two so I'm not in the position to try and reproduce it with a small test case at the moment. I have one developer with one repo exhibiting the problem at the moment. I've updated him to 2.5.1 and the file still doesn't get rebuilt (so the build fails) but the issue could be to do with the database having got wrong information in it, in which case it is too late to upgrade the version of SCons!

There is a sconsign command line tool for doing that.

Is there anything online on how to run it?

Thanks again,



There is a sconsign command line tool for doing that.
Can you try the latest 2.5.1 and see if the problem still exists?
2.3.6 is fairly old.
Also, what command line, platform?
If you can provide a small test case to reproduce that would be helpful.
It's possible this is a known bug.


On Wed, Apr 19, 2017 at 7:55 AM, Hill, Steve (FP COM) <Steve.Hill at cobham.com> wrote:
We have started seeing occasional cases where a source file is reverted to a previous version and the object file is not rebuilt (so, typically, the link fails). We've tried changing the decider to various different ones but they all exhibit the same behaviour. Outputting the dependency tree shows that SCons thinks that the file is up-to-date. We are using SCons 2.3.6 with Python 2.712.

Is there any way to dig into SConsign to understand the problem better?



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