Layer Cannot Be Saved When Identifier Changes for Crate Files

[nvmkuruc]

We had reported in #3386 that layers are not marked dirty when the identifier changes and provided a repro using sdf. Because the layer is not marked dirty, the layer fails to save.

A fix was provided with these commits:
61899b6
76c6f5d

@roggiezhang-nv has observed that the fix doesn't work for usdc. We've provided a new repro below which demonstrates that a renamed usdc layer cannot be saved.

# repro.py
import pathlib
import tempfile

from pxr import Sdf
from pxr import Usd

with tempfile.TemporaryDirectory() as temp_directory:
    for file_format in (".usda", ".usdc"):
        file_path = (pathlib.Path(temp_directory) / "new_layer").with_suffix(file_format)
        renamed_file_path = (file_path.parent / "renamed_layer").with_suffix(file_format)
        layer = Sdf.Layer.CreateNew(str(file_path.absolute()))
        print(f"new_layer[{file_format}]>>", layer, layer.dirty)
        print(f"new_layer[{file_format}]>>", layer.Save())
        assert file_path.exists()
        assert not renamed_file_path.exists()
        layer.identifier = str(renamed_file_path.absolute())
        print(f"renamed_layer[{file_format}]>>", layer, layer.dirty)
        print(f"renamed_layer[{file_format}]>>", layer.Save())

repro.py was evaluated using the following command on Linux.

uv run --with usd-core==25.11 --python 3.12 python3 repro.py

[roggiezhang-nv]

I just found it couldn't be reproduced with the above snippet, but you can repro it with the following one. So you can replace d:/test.usd (existing file to open) or d:/test2.usd (new path to save) to any usd file paths.

from pxr import Usd

stage = Usd.Stage.Open("d:/test.usd")
stage.GetRootLayer().identifier = "d:/test2.usd"
stage.GetRootLayer().Save()

[nvmkuruc]

@roggiezhang-nv I've updated the issue description with a revised repro that demonstrates that usda works but usdc does not. Thanks!

[spiffmon]

Thanks for the report - this is an important behavior, which we're going to try to handle at theSdfLayer-level so that it works uniformly for all writable FileFormats, rather than expecting them each to recognize the situation and do something special.

[jesschimein]

Filed as internal issue #USD-11865

(This is an automated message. See here for more information.)