SimplifyBooleanExpression: skip nullable boolean comparisons in Kotlin#839
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SimplifyBooleanExpression: skip nullable boolean comparisons in Kotlin#839
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…s in Kotlin The `shouldSimplifyEqualsOn` override previously only checked for the `IsNullSafe` marker on method invocations (e.g. `x?.fun() == true`), but missed plain nullable boolean comparisons like `nullableBoolean == true` where `nullableBoolean` is `Boolean?`. For non-Java source files (Kotlin), non-method-invocation expressions are now only simplified when their type is primitive boolean, preventing incorrect simplification of nullable Boolean comparisons. Fixes #303
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timtebeek
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Mar 23, 2026
src/main/java/org/openrewrite/staticanalysis/SimplifyBooleanExpression.java
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Co-authored-by: Tim te Beek <timtebeek@gmail.com>
timtebeek
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Mar 23, 2026
| if (j instanceof J.MethodInvocation) { | ||
| return !j.getMarkers().findFirst(IsNullSafe.class).isPresent(); | ||
| } | ||
| return super.shouldSimplifyEqualsOn(j); |
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- Upstream logic has been expanded in SimplifyBooleanExpression: skip nullable boolean comparisons in Kotlin rewrite#7103
https://github.com/openrewrite/rewrite/blob/58a608d32682e21884d4e6024e282592f3c6b53d/rewrite-java/src/main/java/org/openrewrite/java/cleanup/SimplifyBooleanExpressionVisitor.java#L462-L467
greg-at-moderne
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Mar 24, 2026
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LGTM, but I haven't looked at the CI failure.
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Summary
Fixes
shouldSimplifyEqualsOnoverride to handle nullableBoolean?comparisons, not just null-safe method calls (?.)Previously only checked for
IsNullSafemarker on method invocations (e.g.x?.fun() == true), missing plain nullable boolean comparisons likenullableBoolean == trueFor non-Java source files (Kotlin), non-method-invocation expressions are now only simplified when their type is primitive boolean
Fixes Kotlin code with nullable fields in data classes breaks
SimplifyBooleanExpression#303Test plan
Boolean?.toLegacyFlag() = if (this == true) "1" else "0"— preservedtodo.completed == truewithBoolean?field — preservedb == falsewithBoolean?parameter — preservedb != truewithBoolean?parameter — preserved