[Scons-dev] Bug in MSVC_BATCH handling

[Eric Fahlgren]

I'm not a git user, is there a tutorial on how to create a PR?

On Sun, Dec 15, 2019 at 12:49 PM Bill Deegan <bill at baddogconsulting.com>
wrote:

> Generally issues like this should go to the users mailing list.
> (Mainly so searching users mailing list will find issues run into by
> users).
>
> Good catch.
> Any chance you can put together a PR with a test?
> -Bill
>
> On Sun, Dec 15, 2019 at 12:13 PM Eric Fahlgren <ericfahlgren at gmail.com>
> wrote:
>
>> Py 3.7 64, Win 10 64
>> SCons 3.1.1 (but same as master in this case)
>>
>> While cleaning up some old scripts, I uncovered a bug that I've been
>> working around for who knows how long and finally isolated it.
>>
>> Problem: When MSVC_BATCH is enabled globally, files with different target
>> name are built individually, but ignoring the specified $TARGET name.
>> Here's a little example, note the first argument to the "cl" output.
>>
>> Input:
>> env = Environment(MSVC_BATCH=True)
>> bug32 = env.Object(target='file32', source='file.cpp')
>>
>> Output:
>> cl  /FoWIN32\src\\  /c  WIN32\src\file.cpp
>>
>> If you explicitly suppress batching in the Object, then it works fine.
>> Input:
>> obj32 = env.Object(target='file32', source='file.cpp', MSVC_BATCH=False)
>> Output:
>> cl  /FoWIN32\src\file32.obj  /c  WIN32\src\file.cpp
>>
>> I chased this to the logic in Tool.msvc, the function msvc_output_flag
>> where it's checking the state of the MSVC_BATCH variable, and ignores the
>> difference in base name that the function just above (msvc_batch_key)
>> performs, see lines 168-173.  My hack, which seems to work, is to change
>> line 191 in msvc.py from:
>>
>> 191:     if 'MSVC_BATCH' not in env or env.subst('$MSVC_BATCH') in ('0',
>> 'False', '', None):
>>
>> to use the already-working logic in the batch key function like this:
>>
>> 191:    if msvc_batch_key(None, env, target, source) is None:
>>
>> I tried it on single file and multi-file compilations, and from my
>> cursory playing around, this keeps the batched files together and separates
>> out those with different target base names, but then I didn't try all cases
>> or check any other downstream code in the pipeline to see if this would
>> break anything there...
>>
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