Incorrect line numbers for decorated functions

[Wilfred Hughes]

In the code:

def decorator(func):
    return func

@decorator
def defined_twice():
    pass

@decorator
def defined_twice():
    pass

Pyflakes gives the error: twice.py:10: redefinition of function 'defined_twice' from line 5

It ought to be: twice.py:11: redefinition of function 'defined_twice' from line 6

[Jean-Paul Calderone (exarkun)]

Why? The Python AST makes the decision that the first line of a function is the first decorator that applies to it. Pyflakes just propagates this information.

[Wilfred Hughes (yatc18ks0-9a-ngeefk4xa)]

The Python AST gives the line number where the function definition starts, which includes the decorator. However, the fault isn't on that line and the user cannot fix the issue by changing that line.

Given a FunctionDef node:

node.lineno # where the function definition starts
node.lineno + len(node.decorator_list) # where the function name is