Unterminated string literal causes cython compiler to go into an infinite loop.

[culler]

Describe the bug

Running cythonize bug.pyx on the following file bug.pyx hangs:

# cython: language_level=3str

class Bug():
    """Cythonizing this creates an infinite loop."""

    something = "hello"
    
    def dumb(self):
        print("Say something: %s'%self.something)
 
# Local Variables:
# mode: Python
# End

The traceback produced by hitting Control-C says:

Dependencies.py", line 509, in parse_dependencies
    source, literals = strip_string_literals(source)
                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/culler/Library/Python/3.12/lib/python/site-packages/Cython/Build/Dependencies.py", line 349, in strip_string_literals
    while True:
          ^^^^

Code to reproduce the behaviour:

cythonize bug.pyx

Expected behaviour

An error message saying that the file contains an unterminated string literal.

OS

linux and macOS, at least

Python version

3.10 on linux and 3.12 on macOS

Cython version

3.0.8

Additional context

No response

[scoder]

Thanks for the report and the reproducer. That function was bound to be reimplemented at some point, so I just did that in #5994.

[culler]

Thanks!!!