Fix import errors if setuptools is too old

pytensor/link/c/exceptions.py

@@ -1,18 +1,29 @@
-from setuptools.errors import CompileError as BaseCompileError
+try:
+    from setuptools.errors import CompileError as BaseCompileError
+except ImportError:
+    import warnings
+    from distutils.errors import CompileError as BaseCompileError  # type: ignore
+    from importlib.metadata import version
 
+    # These exception classes were made available in setuptools
+    # since v59.0.0 via <https://github.com/pypa/setuptools/pull/2858>
+    # in preparation for distutils deprecation. Complain loudly if they
+    # are not available.
+    setuptools_version = version("setuptools")
+    warnings.warn(
+        f"You appear to be using an ancient version of setuptools: "
+        f"v{setuptools_version}. Please upgrade to at least v59.0.0. "
+        f"Support for this version of setuptools is provisionary and "
+        f"may be removed without warning in the future."
+    )
 
-class MissingGXX(Exception):
-    """
-    This error is raised when we try to generate c code,
-    but g++ is not available.
 
-    """
+class MissingGXX(Exception):
+    """This error is raised when we try to generate c code, but g++ is not available."""
 
 
-class CompileError(BaseCompileError):
-    """This custom `Exception` prints compilation errors with their original
-    formatting.
-    """
+class CompileError(BaseCompileError):  # pyright: ignore
+    """Custom `Exception` prints compilation errors with their original formatting."""
 
     def __str__(self):
         return self.args[0]