Fail on legacy config in modular projects #11702

ascheman · 2026-02-06T09:45:38Z

Summary

Legacy directories and resources that conflict with modular sources now trigger an ERROR instead of WARNING
Prevents silent loss of user-configured sources/resources
AC8 supersedes AC7 which originally used WARNING

Affected configurations in modular projects:

Explicit <sourceDirectory>/<testSourceDirectory> differing from defaults
Default src/main/java or src/test/java existing on filesystem
Explicit <resources>/<testResources> differing from Super POM defaults

Test plan

ProjectBuilderTest#testModularSourcesWithExplicitResourcesIssuesError passes
ProjectBuilderTest#testMixedSourcesModularMainClassicTest passes

Fixes #11701
See #11701 (comment)

🤖 Generated with Claude Code

In modular projects, legacy directories and resources that would be silently ignored now trigger an ERROR instead of WARNING: - Explicit <sourceDirectory>/<testSourceDirectory> differing from defaults - Default src/main/java or src/test/java existing on filesystem - Explicit <resources>/<testResources> differing from Super POM defaults This prevents silent loss of user-configured sources/resources. AC8 supersedes AC7 which originally used WARNING. Fixes apache#11701 See apache#11701 (comment) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

ascheman · 2026-02-06T13:27:44Z

Reviews are welcome, in particular from @elharo and @desruisseaux - thanks!

elharo

not obvious to me how claude code is being used here. Generally I would not expect simply pointing it at this issue without human editing to produce correct results.

elharo · 2026-02-06T18:27:37Z

impl/maven-core/src/main/java/org/apache/maven/project/DefaultProjectBuilder.java

                 *
                 * Additionally, for modular projects, legacy directories are unconditionally
-                 * ignored because it is not clear how to dispatch their content between
+                 * rejected because it is not clear how to dispatch their content between


I don't think this is what we were looking for. The build fails completely, not simply a warning

Proposal: replace "A warning is emitted if …" by "The build fails if …".

elharo · 2026-02-06T18:29:25Z

impl/maven-core/src/main/java/org/apache/maven/project/DefaultProjectBuilder.java

         * </ul>
-         * Legacy directories are unconditionally ignored in modular projects because it is not clear
-         * how to dispatch their content between different modules.
+         * In both cases, the legacy directory conflicts with modular sources and must not be used.


not "and must not be used" but rather the complete build fails.

not "and must not be used" but rather the complete build fails.

Isn't what the next line below is saying?

elharo · 2026-02-06T18:30:36Z

impl/maven-core/src/main/java/org/apache/maven/project/SourceHandlingContext.java

-                            scopeId,
-                            sourcesConfig);
+                    String message = String.format(
+                            "Legacy %s element must not be used because %s resources are configured via %s in <sources>.",


must not be used --> cannot be used in modular projects

elharo · 2026-02-06T18:30:47Z

impl/maven-core/src/main/java/org/apache/maven/project/SourceHandlingContext.java

                if (hasExplicitLegacyResources(resources, scopeId)) {
                    String message = "Legacy " + legacyElement
-                            + " element is ignored because modular sources are configured. "
+                            + " element must not be used because modular sources are configured. "


must not --> cannot

elharo · 2026-02-06T18:31:10Z

impl/maven-core/src/main/java/org/apache/maven/project/SourceHandlingContext.java

-                            scopeId,
-                            sourcesConfig);
+                    String message = String.format(
+                            "Legacy %s element must not be used because %s resources are configured via %s in <sources>.",


elharo · 2026-02-06T18:31:59Z

impl/maven-core/src/test/java/org/apache/maven/project/ProjectBuilderTest.java

-     * Acceptance Criterion: AC2 (unified source tracking for all lang/scope combinations)
+     * Acceptance Criteria:
+     * - AC2 (unified source tracking for all lang/scope combinations)
+     * - AC8 (legacy directories error - supersedes AC7 which originally used WARNING)


not sure how the AC are being used, but shouldn't AC7 be changed rather than superseded?

elharo · 2026-02-06T18:32:48Z

impl/maven-core/src/test/java/org/apache/maven/project/ProjectBuilderTest.java

-     * In modular projects, legacy directories are unconditionally ignored because it is not clear
-     * how to dispatch their content between different modules. A warning is emitted if these
-     * properties are explicitly set (differ from Super POM defaults).
+     * In modular projects, legacy directories must not occur because it is not clear


In modular projects, legacy directories must not occur --> Legacy directories cannot be used in modular projects

- Use "cannot" instead of "must not" in error messages - Update Javadoc: "The build fails" instead of "A warning is emitted"

elharo · 2026-02-10T12:29:20Z

impl/maven-core/src/main/java/org/apache/maven/project/DefaultProjectBuilder.java

                /*
                 * `sourceDirectory`, `testSourceDirectory` and `scriptSourceDirectory`
-                 * are ignored if the POM file contains at least one enabled <source> element
+                 * are not used if the POM file contains at least one enabled <source> element


again here don't we need the build to fail in this case?

ascheman force-pushed the bugfix/11701-fail-on-modular-sources-with-legacy-dirs branch from 70a7358 to c1b431b Compare February 6, 2026 10:05

ascheman marked this pull request as ready for review February 6, 2026 13:27

elharo requested changes Feb 6, 2026

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Address review feedback on wording

a89fc07

- Use "cannot" instead of "must not" in error messages - Update Javadoc: "The build fails" instead of "A warning is emitted"

desruisseaux approved these changes Feb 8, 2026

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elharo requested changes Feb 10, 2026

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Fail on legacy config in modular projects #11702

Fail on legacy config in modular projects #11702

ascheman commented Feb 6, 2026

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ascheman commented Feb 6, 2026

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elharo left a comment

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elharo Feb 6, 2026

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desruisseaux Feb 7, 2026

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ascheman commented Feb 6, 2026

Summary

Test plan

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ascheman commented Feb 6, 2026

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