Message 187627 - Python tracker (original) (raw)

Attached a new patch that improves the following things:

• added some tests;
• the code in the previous message is now handled correctly;
• the patch now raises a proper SyntaxWarning;

There are still several problems though:

• it doesn't work for the global namespace. Is there a way to know if we are inside a function or not?
• the patch leaks, and I couldn't figure out where the leak is;
• I tried to include the name of the variable in the warning, but:
  • PyErr_WarnExplicit wants a const char* as msg and doesn't support formatting;
  • It doesn't seem possible to use other PyErr_Warn* functions here;
  • Using PyUnicode_FromFormat() works, but then I don't know how to convert the result to const char* (I used PyObject_REPR(), but that is probably wrong; PyUnicode_AS_DATA() might work but is deprecated; the PyUnicode_nBYTE_DATA() functions return a Py_UCSn*);
• more testcases are needed

While compiling I got this warning: ./setup.py:330: SyntaxWarning: "name 'why' is already defined but implicitly deleted after end of except clause" except ImportError as why:

This comes from a code like: try: foo() except Exception as why: pass try: bar() except Exception as why: pass

and in this case there shouldn't be any warning. A possible way to fix this is to keep a "whitelist" of locals that are first defined as an except target, but then it will still break if there's a why = ... between the two try/except and it's starting to get too complicated...