Remove redundant condition from has_magic_trailing_comma
#4023
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The second `if` cannot be true at its execution point, because it is
already covered by the first `if`. The condition
`comma.parent.type == syms.subscriptlist` always holds if
`closing.parent.type == syms.trailer` holds, because `subscriptlist`
only appears inside `trailer` in the grammar:
```
trailer: '(' [arglist] ')' | '[' subscriptlist ']' | '.' NAME
subscriptlist: (subscript|star_expr) (',' (subscript|star_expr))* [',']
```
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cc @hauntsaninja - you added some of the condition in 4ebf14d, maybe you can poke a hole in my logic :) Also c4bd2e3 made a change here (removing the |
Looks like the listmaker condition was only used if preview style for that year was off. Turning on the preview style by default meant that that branch was dead. |
JelleZijlstra
added
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The branch is only relevant when There's always a risk with changes like this of unexpected breakage, so it'd be nice to get some assurance like diff-shades. If diff-shades doesn't cover it, I'll look for some projects which use |
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I'll run it on our internal codebase to check. |
Simplify the
has_magic_trailing_commalogic (it will make #3918 a bit easier to implement).The second
ifcannot be true at its execution point, because it is already covered by the firstif. The conditioncomma.parent.type == syms.subscriptlistalways holds ifclosing.parent.type == syms.trailerholds, becausesubscriptlistonly appears insidetrailerin the grammar:NOTE: I split the PR to two commits, the first one is just a refactor with no logical changes, but makes the argument above easier to follow. The commits should be squashed when merging.