logging-log4j2

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Description

When using DefaultLogBuilder log* methods, throwable information that might have been inferred by the created Message object is lost - and DefaultLogBuilder only passes the explicit throwable that was set via LogBuilder.withThrowable(Throwable). This is in contradiction to the regular use of Logger methods that accept message+args - which creates a Message using the configured factory, and then uses Message.getThrowable() to extract the throwable.

This was initially assumed as a bug in log4j-transform-maven-plugin (which converts regular Logger calls to LogBuilder): https://github.com/apache/logging-log4j-transform/issues/169 but I realized that it might be a stretch for the plugin to infer this data at build-time to be able to pass it to .withThrowable.

Suggested Fix

Change DefaultLogBuilder's logMessage(Message) code from logger.logMessage(level, marker, fqcn, location, message, throwable); to logger.logMessage(level, marker, fqcn, location, message, throwable != null ? throwable : message.getThrowable());

Configuration

Version: 2.24.3

Operating system: macOS Sonoma 14.7.2 JDK: eclipse-temurin 17.0.13

Logs

Consider the following code:

        Throwable throwable = new Exception("Oh oh");
        String messageFormat = "Hello, {}!";
        String arg = "Problem";
        logger.error(messageFormat, arg, throwable);
        logger.atError().log(messageFormat, arg, throwable);

results in the following output:

14:30:53.223 [main] ERROR net.kundas.Main - Hello, Problem!
java.lang.Exception: Oh oh
	at net.kundas.Main.main(Main.java:11) [classes/:?]
14:30:53.233 [main] ERROR net.kundas.Main - Hello, Problem!

Reproduction

I've tried recreating it in a unit test, but they seem to be using org.apache.logging.log4j.test.TestLogger, which does this inference in its log method:

        final Throwable t;
        if (throwable == null
                && params != null
                && params.length > 0
                && params[params.length - 1] instanceof Throwable) {
            t = (Throwable) params[params.length - 1];
        } else {
            t = throwable;
        }
        if (t != null) {
            sb.append(' ');
            final ByteArrayOutputStream baos = new ByteArrayOutputStream();
            t.printStackTrace(new PrintStream(baos));
            sb.append(baos);
        }