usdview Python interpreter fails on Windows with Python 3.14

Description

Opening the embedded Python interpreter in usdview on Windows with Python 3.14 fails.

There appear to be two separate issues in pxr/Usdviewq/pythonInterpreter.py:

1. PYTHONSTARTUP paths are inserted directly into generated Python source code without escaping Windows backslashes.
2. The custom Interpreter.showsyntaxerror() override is incompatible with Python 3.14, which now passes a source keyword argument.

Environment

• OS: Windows

• Python: 3.14.7

• OpenUSD: built from source

• usdview: PySide6

• OpenUSD install path:

  复制

  D:\Bibliotheken\OpenUSD\install_py314

Steps to reproduce

1. Build OpenUSD with Python 3.14 on Windows.

2. Start usdview.

3. Open the embedded Python interpreter.

4. Have PYTHONSTARTUP set to a Windows path, for example:

   复制

   C:\Users\Jonas\AppData\Roaming\Code\User\workspaceStorage\...\ms-python.python\pythonrc.py

In my case PYTHONSTARTUP is set by the VS Code Python extension.

Actual result

The interpreter fails while executing the startup file:

Traceback (most recent call last):
  File "C:\Users\Jonas\AppData\Local\Python\pythoncore-3.14-64\Lib\code.py", line 64, in runsource
    code = self.compile(source, filename, symbol)
  File "C:\Users\Jonas\AppData\Local\Python\pythoncore-3.14-64\Lib\codeop.py", line 154, in __call__
    return _maybe_compile(self.compiler, source, filename, symbol, flags=self.compiler.flags)
  ...
  File "<input>", line 1
    g = dict(globals());g["__file__"] = "C:\Users\Jonas\AppData\Roaming\Code\..."
                                        ^
SyntaxError: (unicode error) 'unicodeescape' codec can't decode bytes in position 2-3: truncated \UXXXXXXXX escape

While handling that syntax error, a second exception occurs:

Traceback (most recent call last):
  File "...pxr\Usdviewq\appController.py", line 2706, in _showInterpreter
    self._console = Myconsole(self._interpreter, self._usdviewApi)
  ...
  File "...pxr\Usdviewq\pythonInterpreter.py", line 298, in ExecStartupFile
    self.interpreter.runsource(...)
  File "...\Python\pythoncore-3.14-64\Lib\code.py", line 67, in runsource
    self.showsyntaxerror(filename, source=source)

TypeError: Interpreter.showsyntaxerror() got an unexpected keyword argument 'source'

Expected result

The usdview Python interpreter should open normally and execute the configured PYTHONSTARTUP file.

Issue 1: Windows path escaping

ExecStartupFile() currently generates Python source containing the startup path:

'g["__file__"] = "{0}";'
'f = open("{0}", "rb");'
'exec(compile(f.read(), "{0}", "exec"), g);'

For a Windows path such as:

C:\Users\Jonas\...

this produces a Python string containing \U, which is interpreted as the start of a Unicode escape sequence.

Using the repr() formatting conversion should avoid this:

self.interpreter.runsource(
    'g = dict(globals());'
    'g["__file__"] = {0!r};'
    'f = open({0!r}, "rb");'
    'exec(compile(f.read(), {0!r}, "exec"), g);'
    'f.close();'
    'del g["__file__"];'
    'globals().update(g);'.format(path))

Issue 2: Python 3.14 showsyntaxerror() API change

Python 3.14's InteractiveInterpreter.runsource() calls:

self.showsyntaxerror(filename, source=source)

The usdview interpreter overrides showsyntaxerror() without accepting this argument.

For example, changing:

def showsyntaxerror(self, filename=None):
    self._outputBrush = QtGui.QBrush(QtGui.QColor('#ffcc63'))
    try:
        InteractiveInterpreter.showsyntaxerror(self, filename)
    finally:
        self._outputBrush = None

to something like:

def showsyntaxerror(self, filename=None, **kwargs):
    self._outputBrush = QtGui.QBrush(QtGui.QColor('#ffcc63'))
    try:
        InteractiveInterpreter.showsyntaxerror(self, filename, **kwargs)
    finally:
        self._outputBrush = None

appears to make the override compatible with Python 3.14 while remaining backwards compatible.

Workaround

Clearing PYTHONSTARTUP before launching usdview avoids the first problem:

set "PYTHONSTARTUP="
python "%USD_ROOT%\bin\\\usdview" %*

However, the showsyntaxerror() incompatibility can still occur whenever a syntax error is processed by the interpreter.

Additional notes

The two problems seem independent:

• The Windows path issue is exposed when PYTHONSTARTUP contains a normal Windows path.
• The showsyntaxerror() issue is caused by an API change in Python 3.14.

I can provide a PR with the changes above if this approach is considered appropriate.