Switch JDK >= 9 to only use maven.compiler.release #543

gnodet · 2025-10-15T05:27:48Z

The pom does not define maven.compiler.source and maven.compiler.target anymore

Bukama · 2025-10-15T06:03:58Z

pom.xml

+        <jdk>[,9)</jdk>
+      </activation>
+      <properties>
+        <maven.compiler.source>${maven.compiler.target}</maven.compiler.source>


Afaik the compiler plugin handles this itself, so you can always use release, doesn't it?

https://maven.apache.org/plugins/maven-compiler-plugin/examples/set-compiler-release.html

We cannot mix -source and --release when invoking javac (tool documentation). The version 3 of the compiler plugin had some build-in logic for choosing which option to use. But in version 4, this logic has been removed. The rational are:

One goal of version 4 of the compiler plugin is to reduce the amount of heuristic rules and be more straightforward in the arguments passed to javac.

Since Maven 4 can be executed only on Java 17 or later, the --release option can be used unconditionally, except when using toolchains or forked compiler. So we could start forgetting about -source.

There is a risk of ambiguity if both <release> and <source> are specified with inconsistent values. I presume that this is the reason why javac rejects the case where the two options are specified.

@desruisseaux

The --release option is not supported using JDK 8. However, since Compiler plugin version 3.13.0 you can use the release property also on JDK 8. The plugin will convert it to source and target automatically.

(from https://maven.apache.org/plugins/maven-compiler-plugin/examples/set-compiler-release.html#Usage_on_JDK_8)

For m-compiler-p 4.xx requiring Java 17+ this profile is anyhow not relevant.

Not sure about m-javadoc-p though as that evaluates the same properties...

@kwin : the documentation that you cite is specific to Maven Compiler Plugin 3.x. It is not standard Java and does not apply anymore to Maven Compiler Plugin 4.x.

kwin · 2025-10-20T11:25:48Z

pom.xml

      <properties>
        <!-- https://maven.apache.org/plugins/maven-compiler-plugin/examples/set-compiler-release.html, affects m-compiler-p and m-javadoc-p -->
-        <maven.compiler.release>${maven.compiler.target}</maven.compiler.release>
+        <maven.compiler.release>8</maven.compiler.release>


why hardcoded to 8?

That's the current default value. My aim was to have a similar behaviour.

Have you tried overwriting this in a child outside a profile. Not sure which one takes precedence to be honest: https://maven.apache.org/guides/introduction/introduction-to-profiles.html#Profile_Order

The child always takes precedence over the parent, parent profiles included.

slawekjaranowski · 2025-10-27T23:22:12Z

@gnodet we need update documentation:

maven-apache-parent/docs/src/site/apt/index.apt.vm

Lines 80 to 83 in cdf6781

    
           ** The compiler plugin is set target <<Java $context.get("maven.compiler.target")>> (<<<maven.compiler.target>>> property) 
        
              and assume $context.get("project.build.sourceEncoding") source encoding (<<<project.build.sourceEncoding>>> property). When being executed 
        
              with JDK 9 or newer also <<<maven.compiler.release>>> is set to the value of property <<<maven.compiler.target>>>. 
        
              Therefore its value must not start with <<<1.>>> (use for example <<<8>>> instead of <<<1.8>>>).

slawekjaranowski · 2025-11-10T13:27:42Z

Ok, child project should be simple as possible
How we provide a way to say in child project that want to use eg JDK 17 as target?

slawekjaranowski · 2025-11-10T13:31:58Z

Maybe we need a new property - like javaVersion and child project can set it if needed

desruisseaux · 2025-11-10T13:32:32Z

You can also set target.release to 8 for Java 8 - compiler plugin should ignore it

Not the Maven 4.0.0-beta-3 plugin. It will raise an error. Actually it will forward the parameter verbatim to javac, and javac will raise an error.

slawekjaranowski · 2025-11-10T13:48:47Z

You can also set target.release to 8 for Java 8 - compiler plugin should ignore it

Not the Maven 4.0.0-beta-3 plugin. It will raise an error. Actually it will forward the parameter verbatim to javac, and javac will raise an error.

so it is next reason to introduce new property for java version for child projects.
and maven.compiler.* should be set only here and not touched in child projects

desruisseaux · 2025-11-10T14:01:35Z

Well, my comment was inexact. Maven 4 requires Java 17+, and Java 17 accepts --release 8. So no error should be raised by javac (until Java 8 is not supported anymore).

slachiewicz · 2025-11-10T14:11:08Z

see some challenges apache/maven-compiler-plugin#990

gnodet · 2025-11-10T23:26:41Z

see some challenges apache/maven-compiler-plugin#990

One can still set the maven.compiler.source to 8 when needed.
Are you worried about compatibility ? This is flagged as breaking.

slawekjaranowski · 2025-11-13T08:17:51Z

see some challenges apache/maven-compiler-plugin#990

One can still set the maven.compiler.source to 8 when needed. Are you worried about compatibility ? This is flagged as breaking.

Ok no worry about break changes ...

But if child project override maven.compiler.source we will brek what we want here - only use maven.compiler.release

And should be documented which property should be override be child project to select proper target

Defining maven.compiler.source and maven.compiler.target properties when running on JDK >= 9 has some side effects. Fixes apache#503 Follow-up to apache/maven-apache-parent#543 and apache/maven-apache-parent#550

* Enhance target JDK definition for JDK >= 1 Defining maven.compiler.source and maven.compiler.target properties when running on JDK >= 9 has some side effects. Fixes #503 Follow-up to apache/maven-apache-parent#543 and apache/maven-apache-parent#550 * use javaVersion property --------- Co-authored-by: Slawomir Jaranowski <[email protected]>

ctubbsii

I'm in favor of only defining the release property, and not source and target on newer JDKs, but this will probably break some people. A lot of plugins that do code generation, source formatting, etc., rely on the source/target properties to control their behavior, and not all of them have been updated to understand the release property. So, while this is completely fine for the compiler plugin, users should be aware that it may have unintended consequences for other plugins.

Switch JDK >= 9 to only use maven.compiler.release

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The pom does not define maven.compiler.source and maven.compiler.target anymore

gnodet mentioned this pull request Oct 15, 2025

Enhance target JDK definition for JDK >= 9 apache/maven-parent#505

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Bukama reviewed Oct 15, 2025

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Bukama approved these changes Oct 15, 2025

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gnodet added breaking Pull requests that break existing features enhancement New feature or request labels Oct 16, 2025

kwin reviewed Oct 20, 2025

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gnodet added this to the ASF-36 milestone Nov 10, 2025

Merge branch 'master' into fix/maven-compiler-release

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gnodet merged commit 2d0578a into apache:master Nov 13, 2025
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gnodet mentioned this pull request Nov 13, 2025

Follow-up on maven.compiler.* properties change #550

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slawekjaranowski mentioned this pull request Nov 13, 2025

Introduce javaVersion property for maven.compiler.* configuration #551

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ctubbsii reviewed Nov 18, 2025

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Switch JDK >= 9 to only use maven.compiler.release #543

Switch JDK >= 9 to only use maven.compiler.release #543

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