[Scons-users] Unexpected warning when defining a target twice during reading of SConscripts

[Bill Deegan]

Andrew,

There's no active work at this time on moving the bug tracker.
There's some work in progress code for extracting from tigris.
Any help is most welcome.

-Bill

On Sun, Dec 3, 2017 at 3:51 AM, Andrew Featherstone <
andrew.featherstone at gmail.com> wrote:

> I can create an issue for this on tigris, but how far away is using
> GitHub's issue tracker? This would allow PRs to mention issues in a more
> rich way, allowing us to follow some more of the "Collective Code
> Construction Contract" defined at https://rfc.zeromq.org/spec:22/C4/ .
>
> I can believe it requires a bit of thought, but ultimately it is a case of
> implementing the __eq__ function correctly for Envrionment.
>
> Andrew
>
> On Sat, 02 Dec 2017 21:29:42 -0000, Bill Deegan <bill at baddogconsulting.com>
> wrote:
>
> Andrew,
>
> You wouldn't see it build twice because you cannot due to checking for
> different environments, thus the error.
> There are two different Environments(), so the message is not incorrect.
> Their contents may be equivalent, I know we had a patch to address
> override environments which were equivalent.
>
> Feel free to create a pull request with a fix.
>
> In this specific case it does point out something which has no value in
> the build assuming the two environments are equivalent.
> Whether that's worthy of an error is probably debatable.
>
> There is currently no bug in scons.tigris.org to capture this, so please
> go ahead and file.
>
> I think the issue is the following: (src/engine/SCons/Builder.py line 296)
> if (not t.env is None and not t.env is env and
>
>
> Since there are two different objects, the t.env is env fails.
> Comparing two environments for equality is not done, and indeed could get
> quite complicated as you'll need to compare any dictionaries, lists, sets
> and functions/classes stored in both  Environment()s
>
> Hope that helps.
> -Bill
>
> On Fri, Dec 1, 2017 at 5:54 PM, Andrew Featherstone <
> andrew.featherstone at gmail.com> wrote:
>
>> They might be different instances, but they're also equal. Surely
>> something must be sharing information or we'd see something like
>>
>> scons: Building targets ...
>> simple_cmd(["foo.out"], ["foo.in"])
>> simple_cmd(["foo.out"], ["foo.in"])
>> scons: done building targets.
>>
>> In the logs.
>>
>> Andrew
>>
>>
>> On 2 Dec 2017 00:26, "Bill Deegan" <bill at baddogconsulting.com> wrote:
>>
>> Here's my recipe for finding such in the sources:
>>
>> $ grep -r "Two different environments" src/engine/SCons/
>>
>> src/engine/SCons/Builder.py:                    msg = "Two different
>> environments were specified for target %s,\n\tbut they appear to have the
>> same action: %s" % (t, action.genstring(tlist, slist, t.env))
>>
>>
>> Actually it's probably correct.
>> Each time you call SConscript above, it's creating a new Environment().
>> SConscripts are evaluated basically by python eval.
>> There's no shared context between the two evaluations of the same
>> SConscript in this case.
>>
>>
>> On Fri, Dec 1, 2017 at 3:37 PM, Andrew Featherstone <
>> andrew.featherstone at cantab.net> wrote:
>>
>>> Hi all,
>>>
>>> Here's a simple setup using scons 3.0.1
>>>
>>> $ ls
>>> SConscript  SConstruct  foo.in
>>> $ cat SConstruct
>>> env_a = Environment()
>>> env_b = Environment()
>>> for env in (env_a, env_b):
>>>     SConscript(
>>>         'SConscript'
>>>     )
>>> $ cat SConscript
>>> import shutil
>>>
>>> env_c = Environment()
>>>
>>> def simple_cmd(target, source, env):
>>>     shutil.copy(str(source[0]), str(target[0]))
>>>
>>> env_c.Command('foo.out', 'foo.in', simple_cmd)
>>>
>>> The expected behaviour when running scons is that the foo.out is
>>> produced once. This does happen, but SCons incorrectly (AFAICT) warns that
>>> different environments are used to build the target foo.out:
>>>
>>> $ scons
>>> scons: Reading SConscript files ...
>>>
>>> scons: warning: Two different environments were specified for target
>>> foo.out,
>>>         but they appear to have the same action: simple_cmd(target,
>>> source, env)
>>> File "C:\Users\Andrew\projects\scons-env\SConscript", line 8, in
>>> <module>
>>> scons: done reading SConscript files.
>>> scons: Building targets ...
>>> simple_cmd(["foo.out"], ["foo.in"])
>>> scons: done building targets.
>>>
>>> The output of --taskmastertrace:
>>>
>>>
>>> Taskmaster: Looking for a node to evaluate
>>> Taskmaster:     Considering node <no_state   0   '.'> and its children:
>>> Taskmaster:        <no_state   0   'foo.in'>
>>> Taskmaster:        <no_state   0   'foo.out'>
>>> Taskmaster:        <no_state   0   'SConscript'>
>>> Taskmaster:        <no_state   0   'SConstruct'>
>>> Taskmaster:      adjusted ref count: <pending    1   '.'>, child 'foo.in
>>> '
>>> Taskmaster:      adjusted ref count: <pending    2   '.'>, child
>>> 'foo.out'
>>> Taskmaster:      adjusted ref count: <pending    3   '.'>, child
>>> 'SConscript'
>>> Taskmaster:      adjusted ref count: <pending    4   '.'>, child
>>> 'SConstruct'
>>> Taskmaster:     Considering node <no_state   0   'foo.in'> and its
>>> children:
>>> Taskmaster: Evaluating <pending    0   'foo.in'>
>>>
>>> Task.make_ready_current(): node <pending    0   'foo.in'>
>>> Task.prepare():      node <up_to_date 0   'foo.in'>
>>> Task.executed_with_callbacks(): node <up_to_date 0   'foo.in'>
>>> Task.postprocess():  node <up_to_date 0   'foo.in'>
>>> Task.postprocess():  removing <up_to_date 0   'foo.in'>
>>> Task.postprocess():  adjusted parent ref count <pending    3   '.'>
>>>
>>> Taskmaster: Looking for a node to evaluate
>>> Taskmaster:     Considering node <no_state   0   'foo.out'> and its
>>> children:
>>> Taskmaster:        <up_to_date 0   'foo.in'>
>>> Taskmaster: Evaluating <pending    0   'foo.out'>
>>>
>>> Task.make_ready_current(): node <pending    0   'foo.out'>
>>> Task.prepare():      node <executing  0   'foo.out'>
>>> Task.execute():      node <executing  0   'foo.out'>
>>> Task.executed_with_callbacks(): node <executing  0   'foo.out'>
>>> Task.postprocess():  node <executed   0   'foo.out'>
>>> Task.postprocess():  removing <executed   0   'foo.out'>
>>> Task.postprocess():  adjusted parent ref count <pending    2   '.'>
>>>
>>> Taskmaster: Looking for a node to evaluate
>>> Taskmaster:     Considering node <no_state   0   'SConscript'> and its
>>> children:
>>> Taskmaster: Evaluating <pending    0   'SConscript'>
>>>
>>> Task.make_ready_current(): node <pending    0   'SConscript'>
>>> Task.prepare():      node <up_to_date 0   'SConscript'>
>>> Task.executed_with_callbacks(): node <up_to_date 0   'SConscript'>
>>> Task.postprocess():  node <up_to_date 0   'SConscript'>
>>> Task.postprocess():  removing <up_to_date 0   'SConscript'>
>>> Task.postprocess():  adjusted parent ref count <pending    1   '.'>
>>>
>>> Taskmaster: Looking for a node to evaluate
>>> Taskmaster:     Considering node <no_state   0   'SConstruct'> and its
>>> children:
>>> Taskmaster: Evaluating <pending    0   'SConstruct'>
>>>
>>> Task.make_ready_current(): node <pending    0   'SConstruct'>
>>> Task.prepare():      node <up_to_date 0   'SConstruct'>
>>> Task.executed_with_callbacks(): node <up_to_date 0   'SConstruct'>
>>> Task.postprocess():  node <up_to_date 0   'SConstruct'>
>>> Task.postprocess():  removing <up_to_date 0   'SConstruct'>
>>> Task.postprocess():  adjusted parent ref count <pending    0   '.'>
>>>
>>> Taskmaster: Looking for a node to evaluate
>>> Taskmaster:     Considering node <pending    0   '.'> and its children:
>>> Taskmaster:        <up_to_date 0   'foo.in'>
>>> Taskmaster:        <executed   0   'foo.out'>
>>> Taskmaster:        <up_to_date 0   'SConscript'>
>>> Taskmaster:        <up_to_date 0   'SConstruct'>
>>> Taskmaster: Evaluating <pending    0   '.'>
>>>
>>> Task.make_ready_current(): node <pending    0   '.'>
>>> Task.prepare():      node <executing  0   '.'>
>>> Task.execute():      node <executing  0   '.'>
>>> Task.executed_with_callbacks(): node <executing  0   '.'>
>>> Task.postprocess():  node <executed   0   '.'>
>>>
>>> Taskmaster: Looking for a node to evaluate
>>> Taskmaster: No candidate anymore.
>>>
>>> Any ideas on how to debug this further?
>>>
>>> Andrew
>>>
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>>>
>>>
>>
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>
>
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