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Use reflection to avoid referencing the Kotlin metadata API directly.
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AutoBuilder clients that don't use Kotlin shouldn't have to have the Kotlin runtime on their classpath, even if it is only the annotation-processing classpath. Additionally, the metadata API was recently moved from `kotlinx.*` to `kotlin.*`, and using reflection means we can function with either version.

Fixes #1440.

PiperOrigin-RevId: 637886287
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@eamonnmcmanus
eamonnmcmanus authored and Google Java Core Libraries committed May 28, 2024
1 parent 76be89a commit 260b61e
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Showing 5 changed files with 349 additions and 131 deletions.
28 changes: 0 additions & 28 deletions value/processor/pom.xml
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Expand Up @@ -78,11 +78,6 @@
<groupId>com.squareup</groupId>
<artifactId>javapoet</artifactId>
</dependency>
<dependency>
<groupId>org.jetbrains.kotlinx</groupId>
<artifactId>kotlinx-metadata-jvm</artifactId>
<version>0.9.0</version>
</dependency>
<dependency>
<groupId>org.ow2.asm</groupId>
<artifactId>asm</artifactId>
Expand Down Expand Up @@ -230,21 +225,6 @@
<exclude>com.google.code.findbugs:jsr305</exclude>
</excludes>
</artifactSet>
<filters>
<filter>
<artifact>*:*</artifact>
<excludes>
<!-- Don't include kotlinx-metadata.kotlin_module, etc. We're shading those
libaries and they're only used from Java. Leaving them in the jar creates
"incompatible version" errors from the Kotlin compiler. -->
<exclude>META-INF/*.kotlin_module</exclude>
</excludes>
</filter>
</filters>
<transformers>
<!-- Needed to avoid "No MetadataExtensions instances found in the classpath" from Kotlin reflection. -->
<transformer implementation="org.apache.maven.plugins.shade.resource.ServicesResourceTransformer"/>
</transformers>
<relocations>
<relocation>
<pattern>com.google</pattern>
Expand All @@ -257,14 +237,6 @@
<pattern>com.squareup.javapoet</pattern>
<shadedPattern>autovalue.shaded.com.squareup.javapoet</shadedPattern>
</relocation>
<relocation>
<pattern>kotlin</pattern>
<shadedPattern>autovalue.shaded.kotlin</shadedPattern>
</relocation>
<relocation>
<pattern>kotlinx</pattern>
<shadedPattern>autovalue.shaded.kotlinx</shadedPattern>
</relocation>
<relocation>
<pattern>net.ltgt.gradle.incap</pattern>
<shadedPattern>autovalue.shaded.net.ltgt.gradle.incap</shadedPattern>
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31 changes: 25 additions & 6 deletions value/src/it/functional/pom.xml
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Expand Up @@ -40,11 +40,6 @@
<artifactId>auto-value-annotations</artifactId>
<version>${project.version}</version>
</dependency>
<dependency>
<groupId>com.google.auto.value</groupId>
<artifactId>auto-value</artifactId>
<version>${project.version}</version>
</dependency>
<dependency>
<groupId>com.google.auto.service</groupId>
<artifactId>auto-service</artifactId>
Expand Down Expand Up @@ -158,6 +153,18 @@
</dependency>
</dependencies>
<configuration>
<annotationProcessorPaths>
<path>
<groupId>com.google.auto.value</groupId>
<artifactId>auto-value</artifactId>
<version>${project.version}</version>
</path>
<path>
<groupId>org.jetbrains.kotlin</groupId>
<artifactId>kotlin-metadata-jvm</artifactId>
<version>2.0.0</version>
</path>
</annotationProcessorPaths>
<source>${java.specification.version}</source>
<target>${java.specification.version}</target>
<compilerArgs>
Expand Down Expand Up @@ -202,7 +209,7 @@
</goals>
</execution>
</executions>
</plugin>
</plugin>
</plugins>
</build>

Expand All @@ -223,6 +230,18 @@
</dependency>
</dependencies>
<configuration>
<annotationProcessorPaths>
<path>
<groupId>com.google.auto.value</groupId>
<artifactId>auto-value</artifactId>
<version>${project.version}</version>
</path>
<path>
<groupId>org.jetbrains.kotlin</groupId>
<artifactId>kotlin-metadata-jvm</artifactId>
<version>2.0.0</version>
</path>
</annotationProcessorPaths>
<source>${java.specification.version}</source>
<target>${java.specification.version}</target>
<compilerArgs>
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103 changes: 6 additions & 97 deletions value/src/main/java/com/google/auto/value/processor/AutoBuilderProcessor.java
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Expand Up @@ -21,11 +21,9 @@
import static com.google.auto.common.MoreStreams.toImmutableList;
import static com.google.auto.common.MoreStreams.toImmutableMap;
import static com.google.auto.common.MoreStreams.toImmutableSet;
import static com.google.auto.common.MoreTypes.asTypeElement;
import static com.google.auto.value.processor.AutoValueProcessor.OMIT_IDENTIFIERS_OPTION;
import static com.google.auto.value.processor.ClassNames.AUTO_ANNOTATION_NAME;
import static com.google.auto.value.processor.ClassNames.AUTO_BUILDER_NAME;
import static com.google.auto.value.processor.ClassNames.KOTLIN_METADATA_NAME;
import static java.util.stream.Collectors.joining;
import static java.util.stream.Collectors.toMap;
import static javax.lang.model.util.ElementFilter.constructorsIn;
Expand All @@ -48,7 +46,6 @@
import java.lang.reflect.Field;
import java.util.AbstractMap.SimpleEntry;
import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.NavigableSet;
Expand All @@ -72,12 +69,6 @@
import javax.lang.model.type.TypeKind;
import javax.lang.model.type.TypeMirror;
import javax.tools.JavaFileObject;
import kotlinx.metadata.Attributes;
import kotlinx.metadata.KmClass;
import kotlinx.metadata.KmConstructor;
import kotlinx.metadata.KmValueParameter;
import kotlinx.metadata.jvm.KotlinClassHeader;
import kotlinx.metadata.jvm.KotlinClassMetadata;
import net.ltgt.gradle.incap.IncrementalAnnotationProcessor;
import net.ltgt.gradle.incap.IncrementalAnnotationProcessorType;

Expand All @@ -104,11 +95,13 @@ public Set<String> getSupportedOptions() {
}

private TypeMirror javaLangVoid;
private KotlinMetadata kotlinMetadata;

@Override
public synchronized void init(ProcessingEnvironment processingEnv) {
super.init(processingEnv);
javaLangVoid = elementUtils().getTypeElement("java.lang.Void").asType();
kotlinMetadata = new KotlinMetadata(errorReporter());
}

// The handling of @AutoBuilder to generate annotation implementations needs some explanation.
Expand Down Expand Up @@ -464,12 +457,13 @@ private Executable findExecutable(

private ImmutableList<Executable> findRelevantExecutables(
TypeElement ofClass, String callMethod, TypeElement autoBuilderType) {
Optional<AnnotationMirror> kotlinMetadata = kotlinMetadataAnnotation(ofClass);
Optional<AnnotationMirror> kotlinMetadataAnnotation =
kotlinMetadata.kotlinMetadataAnnotation(ofClass);
List<? extends Element> elements = ofClass.getEnclosedElements();
Stream<Executable> relevantExecutables =
callMethod.isEmpty()
? kotlinMetadata
.map(a -> kotlinConstructorsIn(a, ofClass).stream())
? kotlinMetadataAnnotation
.map(a -> kotlinMetadata.kotlinConstructorsIn(a, ofClass).stream())
.orElseGet(() -> constructorsIn(elements).stream().map(Executable::of))
: methodsIn(elements).stream()
.filter(m -> m.getSimpleName().contentEquals(callMethod))
Expand Down Expand Up @@ -582,91 +576,6 @@ private boolean visibleFrom(Element element, PackageElement fromPackage) {
}
}

private Optional<AnnotationMirror> kotlinMetadataAnnotation(Element element) {
// It would be MUCH simpler if we could just use ofClass.getAnnotation(Metadata.class).
// However that would be unsound. We want to shade the Kotlin runtime, including
// kotlin.Metadata, so as not to interfere with other things on the annotation classpath that
// might have a different version of the runtime. That means that if we referenced
// kotlin.Metadata.class here we would actually be referencing
// autovalue.shaded.kotlin.Metadata.class. Obviously the Kotlin class doesn't have that
// annotation.
return element.getAnnotationMirrors().stream()
.filter(
a ->
asTypeElement(a.getAnnotationType())
.getQualifiedName()
.contentEquals(KOTLIN_METADATA_NAME))
.<AnnotationMirror>map(a -> a) // get rid of that stupid wildcard
.findFirst();
}

/**
* Use Kotlin reflection to build {@link Executable} instances for the constructors in {@code
* ofClass} that include information about which parameters have default values.
*/
private ImmutableList<Executable> kotlinConstructorsIn(
AnnotationMirror metadata, TypeElement ofClass) {
ImmutableMap<String, AnnotationValue> annotationValues =
AnnotationMirrors.getAnnotationValuesWithDefaults(metadata).entrySet().stream()
.collect(toImmutableMap(e -> e.getKey().getSimpleName().toString(), e -> e.getValue()));
// We match the KmConstructor instances with the ExecutableElement instances based on the
// parameter names. We could possibly just assume that the constructors are in the same order.
Map<ImmutableSet<String>, ExecutableElement> map =
constructorsIn(ofClass.getEnclosedElements()).stream()
.collect(toMap(c -> parameterNames(c), c -> c, (a, b) -> a, LinkedHashMap::new));
ImmutableMap<ImmutableSet<String>, ExecutableElement> paramNamesToConstructor =
ImmutableMap.copyOf(map);
KotlinClassHeader header =
new KotlinClassHeader(
(Integer) annotationValues.get("k").getValue(),
intArrayValue(annotationValues.get("mv")),
stringArrayValue(annotationValues.get("d1")),
stringArrayValue(annotationValues.get("d2")),
(String) annotationValues.get("xs").getValue(),
(String) annotationValues.get("pn").getValue(),
(Integer) annotationValues.get("xi").getValue());
KotlinClassMetadata.Class classMetadata =
(KotlinClassMetadata.Class) KotlinClassMetadata.readStrict(header);
KmClass kmClass = classMetadata.getKmClass();
ImmutableList.Builder<Executable> kotlinConstructorsBuilder = ImmutableList.builder();
for (KmConstructor constructor : kmClass.getConstructors()) {
ImmutableSet.Builder<String> allBuilder = ImmutableSet.builder();
ImmutableSet.Builder<String> optionalBuilder = ImmutableSet.builder();
for (KmValueParameter param : constructor.getValueParameters()) {
String name = param.getName();
allBuilder.add(name);
if (Attributes.getDeclaresDefaultValue(param)) {
optionalBuilder.add(name);
}
}
ImmutableSet<String> optional = optionalBuilder.build();
ImmutableSet<String> all = allBuilder.build();
ExecutableElement javaConstructor = paramNamesToConstructor.get(all);
if (javaConstructor != null) {
kotlinConstructorsBuilder.add(Executable.of(javaConstructor, optional));
}
}
return kotlinConstructorsBuilder.build();
}

private static int[] intArrayValue(AnnotationValue value) {
@SuppressWarnings("unchecked")
List<AnnotationValue> list = (List<AnnotationValue>) value.getValue();
return list.stream().mapToInt(v -> (int) v.getValue()).toArray();
}

private static String[] stringArrayValue(AnnotationValue value) {
@SuppressWarnings("unchecked")
List<AnnotationValue> list = (List<AnnotationValue>) value.getValue();
return list.stream().map(AnnotationValue::getValue).toArray(String[]::new);
}

private static ImmutableSet<String> parameterNames(ExecutableElement executableElement) {
return executableElement.getParameters().stream()
.map(v -> v.getSimpleName().toString())
.collect(toImmutableSet());
}

private static final ElementKind ELEMENT_KIND_RECORD = elementKindRecord();

private static ElementKind elementKindRecord() {
Expand Down
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