gnodet opened a new issue, #13839:
URL: https://github.com/apache/maven/issues/13839
## Summary
`org.apache.maven.api.di.MojoExecutionScoped` (in `maven-api-di`) is an
unfinished, unusable annotation that should be deprecated on the `maven-4.0.x`
branch and removed in a future major version.
## Why it is unusable
1. **Guice binding is commented out.**
`MojoExecutionScopeModule.configure()` has the v4 annotation binding explicitly
commented out:
```java
// bindScope(org.apache.maven.api.di.MojoExecutionScoped.class, scope);
```
Only the v3 annotation
(`org.apache.maven.execution.scope.MojoExecutionScoped`) is registered in
Guice/Sisu.
2. **No proxy path in maven-di.** Unlike `@SessionScoped` — which creates a
JDK proxy when injected into a wider scope (`SessionScope.createProxy()`) —
`MojoExecutionScope` throws `DIException` if the `ThreadLocal` stack is empty.
Injecting a `@MojoExecutionScoped` component into a `@Singleton` fails at
startup.
3. **No production usage.** No class in Maven itself is annotated with
`org.apache.maven.api.di.MojoExecutionScoped`. All existing usages in ITs and
extensions use the v3 annotation.
4. **v4 plugins don't need it.** For v4 plugins, `DefaultMavenPluginManager`
creates a fresh `Injector` per mojo execution and binds `Session`, `Project`,
`MojoExecution`, and `Log` directly via `bindInstance`. Plain `@Inject` works;
no scope annotation is needed.
## Proposed action for `maven-4.0.x`
Add `@Deprecated` to `org.apache.maven.api.di.MojoExecutionScoped` with a
Javadoc note explaining:
- Why it exists (historical analog to the v3 annotation)
- Why it should not be used (unfinished, no proxy, `ThreadLocal`-based)
- What to use instead (`@SessionScoped` for session-scoped components;
direct `@Inject` for execution context in v4 mojos; v3 `@MojoExecutionScoped`
for legacy extension components in the shared Plexus/Sisu container)
## Longer term
Remove the annotation entirely from `maven-api-di` in a future major
version, once the `maven-4.0.x` deprecation cycle has had time to propagate.
## Related
- MNG-5530 — original `MojoExecutionScope` introduction (ThreadLocal, 2012)
- #13827 — thread-safety discussion that surfaced this gap
-
`impl/maven-core/src/main/java/org/apache/maven/execution/scope/internal/MojoExecutionScopeModule.java`
— commented-out binding
-
`impl/maven-impl/src/main/java/org/apache/maven/impl/di/MojoExecutionScope.java`
— no `createProxy()` path
- `impl/maven-impl/src/main/java/org/apache/maven/impl/di/SessionScope.java`
— has `createProxy()` for comparison
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