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Fix Issue #8653 - Python vtables not considering object size #8683

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Merged
aardappel merged 4 commits into from
Nov 17, 2025
Merged

Fix Issue #8653 - Python vtables not considering object size #8683

aardappel merged 4 commits into from
Nov 17, 2025

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@jtdavis777
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@jtdavis777 jtdavis777 commented Aug 26, 2025 •
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Fixes #8653

added object size to the vtable lookup tuple.

Problem output:

>>> import python.flatbuffers as flatbuffers
>>> builder = flatbuffers.Builder()
>>> builder.StartObject(1)
>>> builder.PrependInt32Slot(0, 1, 0)
>>> obj1 = builder.EndObject()
>>>     
>>> builder.StartObject(1)
>>> builder.PrependInt64Slot(0, 2, 0)
>>> obj2 = builder.EndObject()
>>> builder.Finish(obj2)
992
>>> builder.Output()
bytearray(b'\x04\x00\x00\x00\xf2\xff\xff\xff\x02\x00\x00\x00\x00\x00\x00\x00\x00\x00\x06\x00\x08\x00\x04\x00\x06\x00\x00\x00\x01\x00\x00\x00')

Fixed output:

>>> import python.flatbuffers as flatbuffers
>>> builder = flatbuffers.Builder()
>>> builder.StartObject(1)
>>> builder.PrependInt32Slot(0, 1, 0)
>>> obj1 = builder.EndObject()
>>>     
>>> builder.StartObject(1)
>>> builder.PrependInt64Slot(0, 2, 0)
>>> obj2 = builder.EndObject()
>>> builder.Finish(obj2)
984
>>> builder.Output()
bytearray(b'\x0c\x00\x00\x00\x00\x00\x06\x00\x0e\x00\x04\x00\x06\x00\x00\x00\x02\x00\x00\x00\x00\x00\x00\x00\x00\x00\x06\x00\x08\x00\x04\x00\x06\x00\x00\x00\x01\x00\x00\x00')

@jtdavis777 jtdavis777 force-pushed the fix/python_vtables branch 2 times, most recently from daf8289 to eda12f5 Compare August 29, 2025 12:49
@jtdavis777
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jtdavis777 commented Nov 5, 2025

@aardappel could I also trouble you to look over this PR? I don't think the repo has a python maintainer listed.

aardappel
aardappel reviewed Nov 11, 2025
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@jtdavis777 jtdavis777 requested a review from aardappel November 11, 2025 16:23
@aardappel aardappel merged commit e3ee248 into google:master Nov 17, 2025
49 checks passed
@jtdavis777 jtdavis777 deleted the fix/python_vtables branch November 19, 2025 00:14
TJKoury pushed a commit to DigitalArsenal/flatbuffers that referenced this pull request Nov 19, 2025
@jtdavis777 @aardappel @TJKoury
Fix Issue google#8653 - Python vtables not considering object size (g…
e7c23e1 
…oogle#8683)

* have vtables consider size

* simplification from comment

---------

Co-authored-by: Wouter van Oortmerssen <aardappel@gmail.com>
TJKoury pushed a commit to DigitalArsenal/flatbuffers that referenced this pull request Nov 19, 2025
@jtdavis777 @aardappel @TJKoury
Fix Issue google#8653 - Python vtables not considering object size (g…
cf08947 
…oogle#8683)

* have vtables consider size

* simplification from comment

---------

Co-authored-by: Wouter van Oortmerssen <aardappel@gmail.com>
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[Python] Object size is not considered during vtable de-duplication

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@jtdavis777 @aardappel