PR 6517 improves syntax error messages for invalid numerical literals.
>>> 012
File "<stdin>", line 1
SyntaxError: leading zeros in decimal integer literals are not permitted; use an 0o prefix for octal integers
>>> 0o129
File "<stdin>", line 1
SyntaxError: invalid digit '9' in octal literal
>>> 0o
File "<stdin>", line 1
SyntaxError: invalid octal literal
>>> 1_2_
File "<stdin>", line 1
SyntaxError: invalid decimal literal
>>> 0.1_2_
File "<stdin>", line 1
SyntaxError: invalid decimal literal
>>> 12e+
File "<stdin>", line 1
SyntaxError: invalid decimal literal
>>> 12e+1_
File "<stdin>", line 1
SyntaxError: invalid decimal literal
"SyntaxError: invalid token" was emitted before.
No tests yet. Suggestions about error messages are welcome.