Auto-detect quarkus and default to dao with the proper session type

Unless there's a different session getter defined

tooling/metamodel-generator/src/main/java/org/hibernate/jpamodelgen/Context.java

@@ -95,6 +95,9 @@ public final class Context {
 	// keep track of which named queries have been checked
 	private final Set<String> checkedNamedQueries = new HashSet<>();
 
+	private boolean usesQuarkusOrm = false;
+	private boolean usesQuarkusReactive = false;
+
 	public Context(ProcessingEnvironment processingEnvironment) {
 		this.processingEnvironment = processingEnvironment;
 
@@ -390,4 +393,20 @@ public final class Context {
 	public boolean checkNamedQuery(String name) {
 		return checkedNamedQueries.add(name);
 	}
+
+	public void setUsesQuarkusOrm(boolean b) {
+		usesQuarkusOrm = b;
+	}
+	
+	public boolean usesQuarkusOrm() {
+		return usesQuarkusOrm;
+	}
+
+	public void setUsesQuarkusReactive(boolean b) {
+		usesQuarkusReactive = b;
+	}
+	
+	public boolean usesQuarkusReactive() {
+		return usesQuarkusReactive;
+	}
 }

tooling/metamodel-generator/src/main/java/org/hibernate/jpamodelgen/JPAMetaModelEntityProcessor.java

@@ -174,12 +174,29 @@ public class JPAMetaModelEntityProcessor extends AbstractProcessor {
 				context.getProcessingEnvironment().getElementUtils()
 						.getPackageElement( "io.quarkus.hibernate.orm" );
 
+		PackageElement quarkusOrmPanachePackage =
+				context.getProcessingEnvironment().getElementUtils()
+						.getPackageElement( "io.quarkus.hibernate.orm.panache" );
+		PackageElement quarkusReactivePanachePackage =
+				context.getProcessingEnvironment().getElementUtils()
+						.getPackageElement( "io.quarkus.hibernate.reactive.panache" );
+		if ( quarkusReactivePanachePackage != null
+				&& quarkusOrmPanachePackage != null ) {
+			context.logMessage(
+					Diagnostic.Kind.WARNING,
+					"Both Quarkus Hibernate ORM and Hibernate Reactive with Panache detected: this is not supported, so will proceed as if none were there"
+			);
+			quarkusOrmPanachePackage = quarkusReactivePanachePackage = null;
+		}
+		
 		context.setAddInjectAnnotation( jakartaInjectPackage != null );
 		context.setAddNonnullAnnotation( jakartaAnnotationPackage != null );
 		context.setAddGeneratedAnnotation( jakartaAnnotationPackage != null );
 		context.setAddDependentAnnotation( jakartaContextPackage != null );
 		context.setAddTransactionScopedAnnotation( jakartaTransactionsPackage != null );
 		context.setQuarkusInjection( quarkusOrmPackage != null );
+		context.setUsesQuarkusOrm( quarkusOrmPanachePackage != null );
+		context.setUsesQuarkusReactive( quarkusReactivePanachePackage != null );
 
 		final Map<String, String> options = environment.getOptions();
 

tooling/metamodel-generator/src/main/java/org/hibernate/jpamodelgen/annotation/AnnotationMetaEntity.java

@@ -58,6 +58,8 @@ import java.util.Set;
 import java.util.StringTokenizer;
 import java.util.regex.Pattern;
 
+import jakarta.persistence.EntityManager;
+
 import static java.beans.Introspector.decapitalize;
 import static java.lang.Boolean.FALSE;
 import static java.util.Collections.emptyList;
@@ -407,6 +409,12 @@ public class AnnotationMetaEntity extends AnnotationMeta {
 				sessionType = getter.getReturnType().toString();
 			}
 		}
+		else if ( element.getKind() == ElementKind.INTERFACE
+				&& ( context.usesQuarkusOrm() || context.usesQuarkusReactive() ) ) {
+			// if we don't have a getter, but we're in Quarkus, we know how to find the default sessions
+			repository = true;
+			sessionType = setupQuarkusDaoConstructor();
+		}
 		if ( !repository && jakartaDataRepository ) {
 			repository = true;
 			sessionType = HIB_STATELESS_SESSION;
@@ -514,6 +522,41 @@ public class AnnotationMetaEntity extends AnnotationMeta {
 		return sessionType;
 	}
 
+	/**
+	 * For Quarkus, we generate a constructor with injection for EntityManager in ORM,
+	 * and in HR, we define the static session getter.
+	 */
+	private String setupQuarkusDaoConstructor() {
+		final String typeName = element.getSimpleName().toString() + '_';
+		final String sessionVariableName = getSessionVariableName( sessionType );
+
+		if ( context.usesQuarkusOrm() ) {
+			String name = "getEntityManager";
+			putMember( name,
+					new RepositoryConstructor(
+							this,
+							typeName,
+							name,
+							sessionType,
+							sessionVariableName,
+							dataStore(), 
+							context.addInjectAnnotation(),
+							context.addNonnullAnnotation(),
+							false,
+							false,
+							true
+							)
+					);
+			return Constants.ENTITY_MANAGER;
+		}
+		else {
+			importType( Constants.QUARKUS_SESSION_OPERATIONS );
+			// use this getter to get the method, do not generate an injection point for its type
+			sessionGetter = "SessionOperations.getSession()";
+			return Constants.UNI_MUTINY_SESSION;
+		}
+	}
+
 	/**
 	 * The session getter method doesn't have to be a JavaBeans-style
 	 * getter. It can be any method with no parameters and one of the

tooling/metamodel-generator/src/main/java/org/hibernate/jpamodelgen/util/Constants.java

@@ -94,6 +94,7 @@ public final class Constants {
 	public static final String HIB_SESSION_FACTORY = "org.hibernate.SessionFactory";
 	public static final String HIB_STATELESS_SESSION = "org.hibernate.StatelessSession";
 	public static final String MUTINY_SESSION = "org.hibernate.reactive.mutiny.Mutiny.Session";
+	public static final String QUARKUS_SESSION_OPERATIONS = "io.quarkus.hibernate.reactive.panache.common.runtime.SessionOperations";
 
 	public static final String TUPLE = "jakarta.persistence.Tuple";