gnodet opened a new pull request, #1144:
URL: https://github.com/apache/maven-compiler-plugin/pull/1144
## Summary
Adds an alternative incremental compilation strategy based on ABI
(Application Binary Interface) fingerprinting, alongside the existing
timestamp-based `IncrementalBuild`.
When enabled via `-Dmaven.compiler.incrementalStrategy=abi`, the compiler:
- **Extracts per-type dependencies** during javac's ANALYZE phase,
classifying each as signature-level (affects ABI consumers) or
implementation-level (body-only)
- **Computes ABI fingerprints** from the public API surface (method
signatures, field types, constants, generics, throws clauses)
- **Detects minimal recompilation sets**: body-only changes compile just the
changed file; ABI changes cascade through signature consumers transitively and
implementation consumers directly
- **Tracks cross-module ABI changes** via `.abi-fingerprints` manifests for
reactor builds
- **Caches external dependency fingerprints** by JAR identity (size + mtime)
to avoid redundant bytecode analysis
- **Supports annotation processor classification**
(isolating/aggregating/unknown) following the same META-INF convention as Gradle
### Key differences from the existing timestamp-based approach
| Aspect | Timestamp (current) | ABI (new) |
|---|---|---|
| Change detection | File modification time | Content hash (SHA-256) |
| Recompilation granularity | All-or-nothing on any add/delete | Per-type
with dependency cascade |
| Cross-module | Full rebuild on any dep change | Per-type ABI fingerprint
comparison |
| Dependency tracking | None | Signature vs implementation classification |
### Configuration
```xml
<configuration>
<incrementalStrategy>abi</incrementalStrategy>
</configuration>
```
Or via property: `mvn compile -Dmaven.compiler.incrementalStrategy=abi`
Default remains `timestamp` (existing behavior, unchanged).
### New classes
11 classes in `org.apache.maven.plugin.compiler.incremental`:
- `AbiIncrementalBuild` — engine entry point
- `CompilationAnalyzer` — TaskListener for javac ANALYZE phase
- `DependencyScanner` — TreePathScanner for dep classification
- `AbiExtractor` — ABI fingerprint from javax.lang.model
- `BytecodeAnalyzer` — ASM-based bytecode ABI (cross-module fallback)
- `IncrementalState` — persistent binary state
- `AbiManifest` — cross-module fingerprint manifest (versioned format)
- `ExternalAbiResolver` — classpath scanning with JAR caching
- `ProcessorClassification` — annotation processor type discovery
- `ProcessorType` — ISOLATING / AGGREGATING / UNKNOWN enum
- `SourceFileAnalysis` — per-type analysis record
### Test plan
- [x] 81 new unit tests across 8 test classes covering all incremental/ code
- [x] 2 integration tests (body-only change, ABI cascade)
- [x] All 16 existing tests pass unchanged
- [ ] Manual testing on a multi-module reactor project
🤖 Generated with [Claude Code](https://claude.com/claude-code)
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