[DeadCode] Add RemoveDeadIfBlocksRector #7528
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Removes ifs, elseifs, and elses with no body.
Combines them with others when appropriate.
```diff
class RemoveDeadIfBlock
{
public function run($condition)
{
- if ($value) {
- } elseif ($differentValue) {
- if ($differentValue) {
- } else {
- }
-
if ($differentValue) {
echo 'different';
- } elseif ($value) {
- } else {
}
- if ($differentValue) {
- } elseif ($value) {
+ if (!$differentValue && $value) {
echo 'value';
} else {
}
return $differentValue;
}
}
```
We avoid merging `if`` into following conditions
when the `if` itself has a comment, because we
can't tell if the comment will still be correct for
the negated condition.
At first, I tried adding logic to
RemoveDeadIfForeachForRector to remove elseifs
and elses. That worked, but as I added code it
was clunky to have so much unrelated `if` logic
in `for` and `foreach` rector. So I moved it to
a brand new rector with a simpler implementation.
I borrowed significant code from
RemoveAlwaysTrueIfConditionRector as well.
This can serve as support for smarter rectors
like "RemoveAlwaysTrueIf" and my WIP
"RemoveAlwaysFalseIf". Properly modifying `if`s
requires a lot of extra logic that complicates
the implementation of those rectors. In the
future, they can do something simpler like
removing the body statements but leaving the if
structure in place. Then this rector can perform
the restructuring of the if.
I accidentally put an && ! condition rather than an ||, causing elseifs with skippable exprs to get removed rather than being skipped. - Fix the conditional - Add a test for skippable exprs in elseif condition.
john-shaffer
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samsonasik
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Oct 24, 2025
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Removes ifs, elseifs, and elses with no body. Combines them with others when appropriate.
class RemoveDeadIfBlock { public function run($condition) { - if ($value) { - } elseif ($differentValue) { - if ($differentValue) { - } else { - } - if ($differentValue) { echo 'different'; - } elseif ($value) { - } else { } - if ($differentValue) { - } elseif ($value) { + if (!$differentValue && $value) { echo 'value'; - } else { } return $differentValue; } }We avoid merging
ifinto following conditions when theifitself has a comment, because we can't tell if the comment will still be correct for the negated condition.At first, I tried adding logic to RemoveDeadIfForeachForRector to remove elseifs and elses. That worked, but as I added code it was clunky to have so much unrelated
iflogic in aforandforeachrector. So I moved it to a brand new rector with a simpler implementation. I borrowed significant code from RemoveAlwaysTrueIfConditionRector as well.This can serve as support for smarter rectors like "RemoveAlwaysTrueIf" and my WIP "RemoveAlwaysFalseIf". Properly modifying
ifs requires a lot of extra logic that complicates the implementation of those rectors. In the future, they can do something simpler like removing the body statements but leaving the if structure in place. Then this rector can perform the restructuring of the if.