疑问：构建依赖DSL-A的DSL-B项目时，DSL-A的JvmModelInferrer被重复调用？

tl;dr #

tl;dr: When building a DSL-B project that depends on DSL-A, the generateXtext Gradle task runs DSL-A's JvmModelInferrer far more often than necessary, slowing down build times.

Reproduction Setup #

Here's the project structure used to reproduce the issue:

• Root project: ex.xtext.twog
  • Xtext language projects:
    • DSL-A: A standalone Xtext project with its own grammar (grammar a)
    • DSL-B: An Xtext project that references DSL-A's grammar (so grammar b depends on grammar a)
  • Demo projects:
    • demo/demoA: Uses DSL-A, with a sample model: def DefStr java.lang.String
    • demo/demoB: Uses DSL-B (full model content wasn't provided in the original query)

Potential Fixes & Troubleshooting Steps #

Based on common Xtext and Gradle plugin behavior, here are actionable steps to resolve this over-execution:

1. Validate Gradle Task Inputs/Outputs
   Gradle re-runs tasks when it detects changes to inputs or outputs. If generateXtext for DSL-A isn't properly tracking its outputs, it will re-run unnecessarily:

   • Confirm DSL-A's generateXtext task marks its output directories (like src-gen) as task outputs.
   • Ensure DSL-B's build script depends on DSL-A's compiled artifacts (not just source files) so Gradle can recognize when DSL-A's generated code hasn't changed.

2. Adjust Grammar Dependency Scoping
   If DSL-B is pulling in DSL-A's source code instead of pre-built artifacts, it can trigger redundant inference:

   • Configure DSL-B to depend on DSL-A's published .jar (containing the grammar, parser, and generated classes) rather than source-level dependencies.
   • Check that your Xtext Gradle plugin configurations correctly handle transitive dependencies to avoid reprocessing DSL-A's grammar for every DSL-B build.

3. Scope the JvmModelInferrer to DSL-A's Elements
   Ensure DSL-A's inferrer only runs for its own model elements, not DSL-B's:

   • In DSL-A's JvmModelInferrer class, add a check to only process elements from DSL-A's EPackage (e.g., if (element instanceof DSLADefinition) before executing inference logic).
   • Verify DSL-B's setup doesn't accidentally register DSL-A's inferrer for its own model types.

4. Enable Gradle Build Cache
   Reuse previous generateXtext outputs for DSL-A across builds:

   • Add org.gradle.caching=true to your gradle.properties to enable the build cache.
   • Most Xtext plugin tasks are cacheable by default, but double-check any custom task configurations to ensure they support caching.

Debugging to Pinpoint the Issue #

To get more insight into why the inferrer is running repeatedly:

• Run gradle build --info to view detailed task execution logs—this will show exactly why Gradle decided to re-run generateXtext for DSL-A.
• Check for false change triggers, like IDE tools modifying generated files in DSL-A's output directories.

内容的提问来源于stack exchange，提问作者TmTron