Issue 35029: Convert SyntaxWarning exception raised at code generation time to a SyntaxError (original) (raw)

SyntaxError contains more useful information than SyntaxWarning, and SyntaxError is special cased in tracebacks for better reporting. When SyntaxWarning is raised as an exception, the error report doesn't contain information about the source. It is hard to find the source of a SyntaxWarning. Currently:

$ ./python syntaxwarning.py syntaxwarning.py:1: SyntaxWarning: assertion is always true, perhaps remove parentheses? x = 1; assert (x, "msg") $ ./python -We syntaxwarning.py SyntaxWarning: assertion is always true, perhaps remove parentheses? $ ./python -m syntaxwarning /home/serhiy/py/cpython3.7/syntaxwarning.py:1: SyntaxWarning: assertion is always true, perhaps remove parentheses? x = 1; assert (x, "msg") $ ./python -We -m syntaxwarning Traceback (most recent call last): File "/home/serhiy/py/cpython3.7/Lib/runpy.py", line 183, in _run_module_as_main mod_name, mod_spec, code = _get_module_details(mod_name, _Error) File "/home/serhiy/py/cpython3.7/Lib/runpy.py", line 153, in _get_module_details code = loader.get_code(mod_name) File "", line 860, in get_code File "", line 791, in source_to_code File "", line 219, in _call_with_frames_removed SyntaxWarning: assertion is always true, perhaps remove parentheses?

The proposed PR replaces SyntaxWarning with a SyntaxError if the former was raised as an exception:

$ ./python -We syntaxwarning.py File "syntaxwarning.py", line 1 x = 1; assert (x, "msg") ^ SyntaxError: assertion is always true, perhaps remove parentheses? $ ./python -We -m syntaxwarning Traceback (most recent call last): File "/home/serhiy/py/cpython/Lib/runpy.py", line 183, in _run_module_as_main mod_name, mod_spec, code = _get_module_details(mod_name, _Error) File "/home/serhiy/py/cpython/Lib/runpy.py", line 153, in _get_module_details code = loader.get_code(mod_name) File "", line 909, in get_code File "", line 839, in source_to_code File "", line 219, in _call_with_frames_removed File "/home/serhiy/py/cpython/syntaxwarning.py", line 1 x = 1; assert (x, "msg") ^ SyntaxError: assertion is always true, perhaps remove parentheses?

Similar replacement is already performed for warnings raised for unrecognized escape sequences at parsing time (see ).