How to debug TypeError: required field "lineno" missing from expr?

[Steven D'Aprano]

On Mon, 29 Jun 2015 11:14 am, Mark Lawrence wrote:

> Purely as an exercise I've been converting Grant Jenks' pypatt[1] from
> 2.7 to 3.4.  I've managed to sort out most of the required changes by
> checking on what I can see with an AST pretty printer[2].  So it's
> rather frustrating to have the compile stage throw the error given in
> the subject line.

Now now Mark, you know how this works. Where's your COPY and PASTED
traceback? Where's the Short, Self Contained, Correct Example?

http://sscce.org/

Our crystal ball is in no better state than yours :-)


> The code has a call to the ast fix_missing_locations function.  I'm
> aware of the Armin Ronacher tweet[3] stating
> 
> <quote>
> "TypeError: required field "lineno" missing from stmt" — no, what you
> actually mean is "tuple is not a statement'.
> </quote>
> 
> but I don't think this is the problem.

That's what I dislike about Twitter. There's no context, and no way to tell
what Armin is talking about. I've never seen this error, and cannot imagine
how to get it, or what he means by "tuple is not a statement" for that
matter. A tuple can be a statement:

if condition:
    (1, 2)  # Construct a tuple, then throw it away.


> Still I've clearly managed to 
> screw something up somewhere along so line, so any bright ideas as to
> how I can proceed?
> 
> Further would it be worth raising an enhancement request to get some
> better diagnostics from the built-in compile function, 

If you think it is worth waiting months or years before you can actually use
those enhanced diagnostics, sure. What sort of diagnostics?

Peering into my crystal ball, I see that you're maybe generating some code
dynamically, then running something like:

    code = compile(the_text, something, something)

and that's giving you an error. What happens if you do this?

    print(the_text)
    code = compile(the_text, something, something)


Can you extract the offending line that way? What happens if you copy and
paste the_text into a Python file, and then try to import or run that file? 




-- 
Steven