[MPH-220] Evaluating an expression for use in a script fails on Maven 4.0.0-rc-1

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Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
42/100
Issue type
Bug
Clarity
Mostly clear
Activity status
Stale
Tech stack
java
Domain
build-system

Research direction

Reproduce the issue using the provided POM and the help:evaluate entry point with Maven 3.9.9 and Maven 4.0.0-rc-1. Investigate why -q with -DforceStdout produces no output, and verify that the command returns 1.0.0-SNAPSHOT for the supplied expression.

Written by the indexing model from the issue text.

Description

bug priority:major

Nils Breunese opened MPH-220 and commented

https://maven.apache.org/plugins/maven-help-plugin/evaluate-mojo.html shows that to use the value of an expression in a script, you can use this:

mvn help:evaluate -Dexpression=project.version -q -DforceStdout

I use a variant of this in a project and it works fine with Maven 3.9.9, but when I try it with Maven 4.0.0-rc-1, I no longer get the expected output.

Here is a small reproducer POM:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>

  <groupId>com.example</groupId>
  <artifactId>foo</artifactId>
  <version>${revision}</version>
  <packaging>pom</packaging>

  <properties>
    <revision>1.0.0-SNAPSHOT</revision>
  </properties>

  <build>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-help-plugin</artifactId>
        <version>3.5.1</version>
      </plugin>
    </plugins>
  </build>
</project>

This returns 1.0.0-SNAPSHOT with Maven 3.9.9:

❯ mvn help:evaluate -Dexpression=project.version -q -DforceStdout
1.0.0-SNAPSHOT

But there is no output with Maven 4.0.0-rc-1:

❯ mvn help:evaluate -Dexpression=project.version -q -DforceStdout

Note that when I omit the -q flag, then I do see the expected version in the output, but that output is of course not usable in an automated script.

Affects: 3.5.1

Dominant language
Java
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