SONARJAVA-7188 SONARJAVA-4606 Improvements for the rule S7158

[asya-vorobeva]

• Detect zero literals written in any base
• Suggest "isBlank()" for "strip().length()" and "trim().length()" comparisons

[hashicorp-vault-sonar-prod]

SONARJAVA-7188
SONARJAVA-4606

[gitar-bot]

Code Review ✅ Approved 1 closed / 1 findings

🟡 Medium risk · Expanding zero-literal detection and suggesting isBlank() quick fixes changes analyzer findings; trim() replacements could alter behavior for control characters and Unicode whitespace.

Improves rule S7158 to detect zero literals written in any base and to suggest isBlank() for strip().length() and trim().length() comparisons. No open issues found.

✅ 1 closed

Closed: Cross-PR: S7158 and S9432 both flag trim().length() with conflicting advice

📄 java-checks/src/main/java/org/sonar/java/checks/StringIsEmptyCheck.java:132-143 📄 java-checks/src/main/java/org/sonar/java/checks/StringIsEmptyCheck.java:188-196 📄 java-checks-test-sources/default/src/main/java/checks/StringIsBlankCheckSample.java:9-23 📄 java-checks/src/main/java/org/sonar/java/checks/StringIsEmptyCheck.java:59-63 📄 java-checks-test-sources/default/src/main/java/checks/StringIsBlankCheckSample.java:9-11 📄 java-checks-test-sources/default/src/main/java/checks/StringIsBlankCheckSample.java:72-75 📄 java-checks/src/main/java/org/sonar/java/checks/StringIsEmptyCheck.java:143-157 📄 java-checks/src/main/java/org/sonar/java/checks/StringIsEmptyCheck.java:205-213
Breaks when this PR and #6332 are both merged, and both S7158 and S9432 are enabled on code analyzed as Java 11 or later that contains s.trim().length() == 0 (or a related form).

How

1. This PR's StringIsEmptyCheck reports trim().length() compared with 0 or 1, and its quick fix rewrites the comparison to isBlank() as a plain replacement (java-checks/src/main/java/org/sonar/java/checks/StringIsEmptyCheck.java:133-143).
2. In SONARJAVA-7157: Implemented rule S9432 Strings should not be trimmed or stripped just to check if they are blank #6332, S9432Check.visitNode reports the same expressions at the trim() call (java-checks/src/main/java/org/sonar/java/checks/S9432Check.java:77). Its message says to use isBlank() only if Unicode whitespace should count as blank and control characters should not.
3. Each such line therefore gets two issues, placed at different locations and with contradicting messages. The S7158 quick fix silently changes behavior in exactly the case S9432 warns about.
4. For s.strip().length() == 0 and (s.trim()).length() == 0, S7158 suggests isEmpty() while S9432 suggests removing the strip/trim, so the two rules give opposite advice.

Fix

• This PR: Remove the trim() → isBlank() handling from S7158 and leave blankness checks to S9432, or skip trim()/strip() receivers in S7158 so the two rules never overlap.
• SONARJAVA-7157: Implemented rule S9432 Strings should not be trimmed or stripped just to check if they are blank #6332: No change needed if S7158 drops the overlap. Otherwise, coordinate with S7158 so only one rule reports trim().length() comparisons.

Compared b049767 with #6332 at 6a682bc

Verification Rules 1/1 met Repos 3 inspected · PRs 1 inspected

Functional validation No results

Rules 1 passed 2 not applicable

✅ Repository license compliance

Broader impact Repos 3 inspected PRs 1 inspected

Cross-repo 3 repositories inspected 0 open impacts

SonarSource/sonarlint-vscode Inspected
SonarSource/sonarlint-language-server Inspected
SonarSource/sonarlint-intellij Inspected

Cross-PR 1 PR inspected 0 open impacts

PR #6332: SONARJAVA-7157: Implemented rule S9432 Strings should not be trimmed or stripped just to check if they are blank Inspected

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