UsdUtilsComputeAllDependencies - Anonymous layers return empty

[ColinKennedy]

Description of Issue

When using anonymous Layers, UsdUtils.ComputeAllDependencies is empty. I've noted this in the Python binding version but probably the C++ implementation has the same problem.

Steps to Reproduce

1. Make a custom resolver where a Layer's identifier differs from its resolvedPath equivalent
2. Observe the following behavior:

from pxr import Sdf, UsdUtils

layer = Sdf.Layer.CreateAnonymous(".usda")
layer.subLayerPaths.append("/tmp/foo_bar_thing.usda")
layers, assets, unresolved = UsdUtils.ComputeAllDependencies(layer.identifier)

"/tmp/foo_bar_thing.usda" should either be in layers, as [Sdf.Find("/tmp/foo_bar_thing.usda")] or in unresolved ["/tmp/foo_bar_thing.usda"] but it's in neither. layers, assets, and unresolved are all empty.

If you export to a file and then use that Layer's identifier then the "/tmp/foo_bar_thing.usda" path shows up as expected.

import os
import tempfile

from pxr import Sdf, UsdUtils

_, path = tempfile.mkstemp(suffix="_test_usdutils_anonymous.usda")
layer = Sdf.Layer.CreateAnonymous(os.path.splitext(".usda")[1])
layer.subLayerPaths.append("/tmp/foo_bar_thing.usda")
layers1, assets1, unresolved1 = UsdUtils.ComputeAllDependencies(layer.identifier)

layer.Export(path)

layers2, assets2, unresolved2 = UsdUtils.ComputeAllDependencies(path)

layers1, assets1, and unresolved1 are all empty, whereas layers2, assets2, and unresolved2 have the expected data.

System Information (OS, Hardware)

• CentOS 7

Package Versions

• USD: 22.08
• Python 3

Build Flags

A default build_usd.py build

Related Information

A (rather long) usd-interest forum post: https://groups.google.com/g/usd-interest/c/JSfSTNIJRug

[sunyab]

Filed as internal issue #USD-7736