[logback-dev] [JIRA] Updates for LOGBACK-1775: Last argument of log message stripped if Throwable, even when cause is given as well (Issue #876)

19 Oct 2024

      logback / LOGBACK-1775 [Open]
Last argument of log message stripped if Throwable, even when cause is given as well (Issue #876)

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Here's what changed in this issue in the last few minutes.

This issue has been created

View or comment on issue using this link
https://jira.qos.ch/browse/LOGBACK-1775

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 Issue created
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Ceki Gülcü created this issue on 19/Oct/24 17:32

Summary:              Last argument of log message stripped if Throwable, even when cause is given as well (Issue #876)
Issue Type:           Bug
Affects Versions:     1.5.8
Assignee:             Ceki Gülcü
Components:           logback-classic
Created:              19/Oct/24 17:32
Priority:             Major
Reporter:             Ceki Gülcü
Description:

  If a Throwable type is passed to match the last {} argument, it is ignored, and the formatted log message will write {} instead.

  {code:java}
  package com.test;

  import ch.qos.logback.core.Appender;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  import org.slf4j.event.Level;

  public class Test {
    static final Logger log = LoggerFactory.getLogger(Test.class);

    public static void main(String[] args) {
      log.info("SLF4J Version: {}", Logger.class.getPackage().getImplementationVersion());
      log.info("Logback Version: {}", Appender.class.getPackage().getImplementationVersion());

      Exception ex = new CustomException("Some message");
      log.error("Exception Message: {}", ex, ex);

      log.makeLoggingEventBuilder(Level.WARN)
          .setMessage("Exception Message: {}")
          .addArgument(ex)
          .setCause(ex)
          .log();
    }

    static class CustomException extends Exception {
      public CustomException(String msg) {
        super(msg);
      }

      @Override
      public String toString() {
        return "Custom Message";
      }
    }
  }
  {code}

  Expected output:

  [main] INFO com.test.Test -- SLF4J Version: 2.0.15
  [main] INFO com.test.Test -- Logback Version: 1.5.11
  [main] ERROR com.test.Test -- Exception Message: Custom Message
  com.test.Test$CustomException: Some message
  	at com.test.Test.main(Test.java:15)
  [main] WARN com.test.Test -- Exception Message: Custom Message
  com.test.Test$CustomException: Some message
  	at com.test.Test.main(Test.java:15)

  Actual output:

  [main] INFO com.test.Test -- SLF4J Version: 2.0.15
  [main] INFO com.test.Test -- Logback Version: 1.5.11
  [main] ERROR com.test.Test -- Exception Message: {}
  com.test.Test$CustomException: Some message
  	at com.test.Test.main(Test.java:15)
  [main] WARN com.test.Test -- Exception Message: {}
  com.test.Test$CustomException: Some message
  	at com.test.Test.main(Test.java:15)

  Workaround:
  Explicitly calling .toString() on the argument (log.error("Exception Message: {}", ex.toString(), ex)), or adding a bogus extra "" argument (log.error("Exception Message: {}", ex, "", ex)) works as a work around, but causes static analysis tools, including the one in IntelliJ, to warn about it.

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[logback-dev] [JIRA] Updates for LOGBACK-1775: Last argument of log message stripped if Throwable, even when cause is given as well (Issue #876)

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