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https://issues.apache.org/jira/browse/FLINK-40337?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Xiqian Yu resolved FLINK-40337.
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Fix Version/s: cdc-3.7.0
Assignee: Mao Jiayi
Resolution: Fixed
> Preserve operator precedence in generated Janino expressions
> ------------------------------------------------------------
>
> Key: FLINK-40337
> URL: https://issues.apache.org/jira/browse/FLINK-40337
> Project: Flink
> Issue Type: Bug
> Components: Flink CDC
> Reporter: Mao Jiayi
> Assignee: Mao Jiayi
> Priority: Major
> Labels: pull-request-available
> Fix For: cdc-3.7.0
>
>
> When Flink CDC translates a Pipeline transform expression from Calcite SQL
> nodes to Janino code, {{JaninoCompiler}} constructs {{Java.BinaryOperation}}
> nodes and serializes them via {{Java.Rvalue#toString()}}. This method
> concatenates operands directly without considering operator precedence, so
> parentheses present in the original expression are silently dropped.
> For example, the following expressions all change semantics after code
> generation:
> {code}
> (a + b) * c → a + b * c
> (a OR b) AND c → a || b && c
> a / (b * c) → a / b * c
> a - (b - c) → a - b - c
> {code}
> The generated Janino code evaluates with different grouping than the user's
> original transform expression, producing incorrect results without any error
> or warning. Expressions without nesting are unaffected.
> *Expected behavior*: the generated code preserves the original expression's
> semantics — parentheses are retained where grouping matters, and omitted
> where precedence already guarantees correct evaluation order (e.g. {{a + b *
> c}} should stay as-is).
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