Create rule S7473: Use unnamed variable in pattern matching #4919
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romainbrenguier
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romainbrenguier
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leonardo-pilastri-sonarsource
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rules/S7473/java/metadata.json
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| "constantCost": "1min" | ||
| }, | ||
| "tags": [ | ||
| "unused" |
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Let's add the java23 tag
rules/S7473/java/metadata.json
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| "sqKey": "S7473", | ||
| "scope": "All", | ||
| "defaultQualityProfiles": ["Sonar way"], | ||
| "quickfix": "unknown", |
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We can change the value for "quickfix" to targeted as we should be able to implement a quickfix for this one
rules/S7473/java/rule.adoc
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| A variable occurring in pattern matching is unused. | |||
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I don't see the value of this line
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| A variable occurring in pattern matching is unused. |
rules/S7473/java/rule.adoc
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| == Why is this an issue? | ||
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| This may seem harmless, but could lead to confusion and potential errors in your code. |
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We can be a little bit more verbose and specific here, what about:
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| This may seem harmless, but could lead to confusion and potential errors in your code. | |
| Unused variables in pattern matching can cause confusion and make the code harder to understand. They may also lead to potential errors. | |
| For example, if a variable is declared but not used, it may be mistakenly assumed that it has some significance in the code. This can lead to misunderstandings and make the code less readable. |
rules/S7473/java/rule.adoc
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| == How to fix it | ||
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| By replacing unused variables by an unnamed variable `_`, the function's behavior will be the same, but the programmer's intention will be clear. |
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| By replacing unused variables by an unnamed variable `_`, the function's behavior will be the same, but the programmer's intention will be clear. | |
| Replace unused variables with the unnamed variable `_`. This will not change the behavior of the function, but will make the code clearer. |
rules/S7473/java/rule.adoc
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| * https://openjdk.org/jeps/361[JEP 361: Switch Expressions] | ||
| * https://openjdk.org/jeps/394[JEP 394: Pattern Matching for instanceof] | ||
| * https://openjdk.org/jeps/440[JEP 440: Record Patterns] |
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I am not sure if it's valuable here to mention the documentation of switch expressions, pattern matching and records as the rule is not specific to those topics
…laced with unnamed variables
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You can preview this rule here (updated a few minutes after each push).
This is a proposal for a new rule starting with Java 22 thanks to the possibility to use unnamed variables.
Rule idea: https://sonarsource.atlassian.net/browse/SONARJAVA-5433
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A dedicated reviewer checked the rule description successfully for: