[tahoe-lafs-trac-stream] [tahoe-lafs] #1555: add check-miscaptures.py script to check for incorrect variable captures in for loops

[tahoe-lafs]

#1555: add check-miscaptures.py script to check for incorrect variable captures in
for loops
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     Reporter:  davidsarah  |      Owner:  somebody
         Type:  defect      |     Status:  new
     Priority:  major       |  Milestone:  1.10.0
    Component:  code        |    Version:  1.9.0a2
   Resolution:              |   Keywords:  miscapture coding_tools
Launchpad Bug:              |
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Description changed by davidsarah:

Old description:

> The attached script checks for errors in which a variable declared in a
> {{{for}}} loop is captured by a lambda or function definition. If the
> lambda/function is executed after the loop iteration in which it was
> created, it will refer to some later value of the variable, which is
> usually not what was intended.
>
> The script currently produces false positives if a variable is declared
> and used in the same lambda/function within a for loop (i.e. it is not
> captured). I don't intend to fix that until after the Tahoe summit in
> November, probably. However, it produces relatively few false positives
> already, and found some genuine bugs (see next ticket).

New description:

 The attached script checks for errors in which a variable declared in a
 {{{for}}} loop is captured by a lambda or function definition. If the
 lambda/function is executed after the loop iteration in which it was
 created, it will refer to some later value of the variable, which is
 usually not what was intended.

 The script currently produces false positives if a variable is declared
 and used in the same lambda/function within a for loop (i.e. it is not
 captured). I don't intend to fix that until after the Tahoe summit in
 November, probably. However, it produces relatively few false positives
 already, and found some genuine bugs (see #1556).

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Ticket URL: <http://tahoe-lafs.org/trac/tahoe-lafs/ticket/1555#comment:1>
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