fix(java): Fix union type name conflict resolution (#5637)

* fix(java): Fix union type name conflict resolution

* Add version yamls

* fix typo

* chore: update changelog

---------

Co-authored-by: Alberto <[email protected]>

generators/java/generator-utils/src/main/java/com/fern/java/generators/AbstractTypeGenerator.java

@@ -65,7 +65,6 @@ protected List<TypeSpec> getInlineTypeSpecs() {
                             false,
                             ImmutableSet.<String>builder()
                                     .addAll(reservedTypeNames)
-                                    .add(className.simpleName())
                                     .add(name)
                                     .build(),
                             false));

generators/java/generator-utils/src/main/java/com/fern/java/generators/UndiscriminatedUnionGenerator.java

@@ -23,6 +23,8 @@
 import com.fasterxml.jackson.databind.DeserializationContext;
 import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
 import com.fasterxml.jackson.databind.deser.std.StdDeserializer;
+import com.fern.ir.model.commons.Name;
+import com.fern.ir.model.commons.SafeAndUnsafeString;
 import com.fern.ir.model.commons.TypeId;
 import com.fern.ir.model.types.DeclaredTypeName;
 import com.fern.ir.model.types.TypeDeclaration;
@@ -37,6 +39,7 @@
 import com.fern.java.utils.TypeReferenceUtils;
 import com.fern.java.utils.TypeReferenceUtils.ContainerTypeEnum;
 import com.fern.java.utils.TypeReferenceUtils.TypeReferenceToName;
+import com.google.common.collect.ImmutableSet;
 import com.squareup.javapoet.AnnotationSpec;
 import com.squareup.javapoet.ClassName;
 import com.squareup.javapoet.FieldSpec;
@@ -48,6 +51,7 @@
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.HashMap;
+import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
@@ -57,6 +61,8 @@
 import javax.lang.model.element.Modifier;
 
 public final class UndiscriminatedUnionGenerator extends AbstractTypeGenerator {
+    private static final String VISITOR_CLASS_NAME = "Visitor";
+    private static final String VISITOR_CLASS_NAME_UNDERSCORE = "Visitor_";
 
     private static final String TYPE_COMMENT = "If %d, value is of type %s";
     private static final String TYPE_FIELD_NAME = "type";
@@ -79,6 +85,7 @@ public final class UndiscriminatedUnionGenerator extends AbstractTypeGenerator {
     private final ClassName visitorClassName;
     private final ClassName deserializerClassName;
     private final String undiscriminatedUnionPrefix;
+    private final String visitorName;
 
     public UndiscriminatedUnionGenerator(
             ClassName className,
@@ -95,11 +102,33 @@ public UndiscriminatedUnionGenerator(
                         member -> generatorContext.getPoetTypeNameMapper().convertToTypeName(true, member.getType()))));
         if (generatorContext.getCustomConfig().enableInlineTypes()) {
             typeNames.putAll(overrideMemberTypeNames(
-                    className, generatorContext, undiscriminatedUnion, undiscriminatedUnionPrefix));
+                    className, generatorContext, undiscriminatedUnion, reservedTypeNames, undiscriminatedUnionPrefix));
         }
         this.memberTypeNames = typeNames;
         this.duplicatedOuterContainerTypes = getDuplicatedOuterContainerTypes(undiscriminatedUnion);
-        this.visitorClassName = className.nestedClass("Visitor");
+        this.visitorName = visitorName(
+                // We need to take into consideration all ancestor types as well as all sibling types so that
+                // to prevent naming the visitor "Visitor" if we already have a variant or property called that.
+                ImmutableSet.<String>builder()
+                        .addAll(reservedTypeNames)
+                        .addAll(
+                                generatorContext.getCustomConfig().enableInlineTypes()
+                                        ? overriddenTypeDeclarations(
+                                                        className,
+                                                        generatorContext,
+                                                        undiscriminatedUnion,
+                                                        reservedTypeNames,
+                                                        undiscriminatedUnionPrefix)
+                                                .values()
+                                                .stream()
+                                                .map(TypeDeclaration::getName)
+                                                .map(DeclaredTypeName::getName)
+                                                .map(Name::getPascalCase)
+                                                .map(SafeAndUnsafeString::getSafeName)
+                                                .collect(Collectors.toList())
+                                        : List.of())
+                        .build());
+        this.visitorClassName = className.nestedClass(visitorName);
         this.deserializerClassName = className.nestedClass("Deserializer");
         this.undiscriminatedUnionPrefix = undiscriminatedUnionPrefix;
     }
@@ -120,14 +149,19 @@ public static Set<ContainerTypeEnum> getDuplicatedOuterContainerTypes(
     @Override
     public List<TypeDeclaration> getInlineTypeDeclarations() {
         return new ArrayList<>(overriddenTypeDeclarations(
-                        className, generatorContext, undiscriminatedUnion, undiscriminatedUnionPrefix)
+                        className,
+                        generatorContext,
+                        undiscriminatedUnion,
+                        reservedTypeNames,
+                        undiscriminatedUnionPrefix)
                 .values());
     }
 
     private static Map<TypeId, TypeDeclaration> overriddenTypeDeclarations(
             ClassName className,
             AbstractGeneratorContext<?, ?> generatorContext,
             UndiscriminatedUnionTypeDeclaration undiscriminatedUnion,
+            Set<String> reservedTypeNames,
             String undiscriminatedUnionPrefix) {
         Map<TypeId, TypeDeclaration> overriddenTypeDeclarations = new HashMap<>();
 
@@ -149,6 +183,8 @@ private static Map<TypeId, TypeDeclaration> overriddenTypeDeclarations(
                     continue;
                 }
 
+                Set<String> allReservedTypeNames = new HashSet<>(reservedTypeNames);
+
                 String name =
                         rawTypeDeclaration.getName().getName().getPascalCase().getSafeName();
 
@@ -157,6 +193,17 @@ private static Map<TypeId, TypeDeclaration> overriddenTypeDeclarations(
                     name = name.substring(undiscriminatedUnionPrefix.length());
                 }
 
+                boolean valid;
+                do {
+                    valid = !allReservedTypeNames.contains(name);
+
+                    if (!valid) {
+                        name += "_";
+                    }
+                } while (!valid);
+
+                allReservedTypeNames.add(name);
+
                 TypeDeclaration overriddenTypeDeclaration = overrideTypeDeclarationName(rawTypeDeclaration, name);
                 overriddenTypeDeclarations.put(resolvedId.typeId(), overriddenTypeDeclaration);
             }
@@ -169,9 +216,10 @@ private static Map<UndiscriminatedUnionMember, TypeName> overrideMemberTypeNames
             ClassName className,
             AbstractGeneratorContext<?, ?> generatorContext,
             UndiscriminatedUnionTypeDeclaration undiscriminatedUnion,
+            Set<String> reservedTypeNames,
             String undiscriminatedUnionPrefix) {
         Map<TypeId, TypeDeclaration> overriddenDeclarations = overriddenTypeDeclarations(
-                className, generatorContext, undiscriminatedUnion, undiscriminatedUnionPrefix);
+                className, generatorContext, undiscriminatedUnion, reservedTypeNames, undiscriminatedUnionPrefix);
         Map<DeclaredTypeName, ClassName> mapperEnclosingClasses = new HashMap<>();
 
         for (TypeDeclaration override : overriddenDeclarations.values()) {
@@ -403,4 +451,8 @@ private boolean shouldDeserializeWithTypeReference(UndiscriminatedUnionMember me
         }
         return false;
     }
+
+    private static String visitorName(Set<String> reservedTypeNames) {
+        return reservedTypeNames.contains(VISITOR_CLASS_NAME) ? VISITOR_CLASS_NAME_UNDERSCORE : VISITOR_CLASS_NAME;
+    }
 }

generators/java/generator-utils/src/main/java/com/fern/java/generators/UnionGenerator.java

@@ -3,7 +3,9 @@
 import com.fasterxml.jackson.annotation.JsonProperty;
 import com.fasterxml.jackson.annotation.JsonUnwrapped;
 import com.fasterxml.jackson.annotation.JsonValue;
+import com.fern.ir.model.commons.Name;
 import com.fern.ir.model.commons.NameAndWireValue;
+import com.fern.ir.model.commons.SafeAndUnsafeString;
 import com.fern.ir.model.commons.TypeId;
 import com.fern.ir.model.constants.Constants;
 import com.fern.ir.model.types.*;
@@ -14,6 +16,7 @@
 import com.fern.java.generators.union.UnionTypeSpecGenerator;
 import com.fern.java.utils.InlineTypeIdResolver;
 import com.fern.java.utils.NamedTypeId;
+import com.google.common.collect.ImmutableSet;
 import com.squareup.javapoet.AnnotationSpec;
 import com.squareup.javapoet.ClassName;
 import com.squareup.javapoet.FieldSpec;
@@ -46,13 +49,14 @@ public UnionGenerator(
         super(className, generatorContext, reservedTypeNames, isTopLevelClass);
         this.unionTypeDeclaration = unionTypeDeclaration;
         this.overriddenTypeDeclarations =
-                overriddenTypeDeclarations(generatorContext, unionTypeDeclaration, reservedTypeNames);
+                overriddenTypeDeclarations(className, generatorContext, unionTypeDeclaration, reservedTypeNames);
     }
 
     @Override
     public List<TypeDeclaration> getInlineTypeDeclarations() {
-        return new ArrayList<>(overriddenTypeDeclarations(generatorContext, unionTypeDeclaration, reservedTypeNames)
-                .values());
+        return new ArrayList<>(
+                overriddenTypeDeclarations(className, generatorContext, unionTypeDeclaration, reservedTypeNames)
+                        .values());
     }
 
     @Override
@@ -96,6 +100,7 @@ private static PoetTypeNameMapper overriddenTypeNameMapper(
     }
 
     private static Map<TypeId, TypeDeclaration> overriddenTypeDeclarations(
+            ClassName className,
             AbstractGeneratorContext<?, ?> generatorContext,
             UnionTypeDeclaration unionTypeDeclaration,
             Set<String> reservedTypeNames) {
@@ -186,7 +191,21 @@ private ModelUnionTypeSpecGenerator(
                     unionSubType,
                     fernConstants,
                     true,
-                    unionTypeDeclaration.getDiscriminant().getWireValue());
+                    unionTypeDeclaration.getDiscriminant().getWireValue(),
+                    // We need to take into consideration all ancestor types as well as all sibling types so that
+                    // to prevent naming the visitor "Visitor" if we already have a variant or property called that.
+                    ImmutableSet.<String>builder()
+                            .addAll(reservedTypeNames)
+                            .addAll(
+                                    generatorContext.getCustomConfig().enableInlineTypes()
+                                            ? overriddenTypeDeclarations.values().stream()
+                                                    .map(TypeDeclaration::getName)
+                                                    .map(DeclaredTypeName::getName)
+                                                    .map(Name::getPascalCase)
+                                                    .map(SafeAndUnsafeString::getSafeName)
+                                                    .collect(Collectors.toList())
+                                            : List.of())
+                            .build());
         }
 
         @Override

generators/java/generator-utils/src/main/java/com/fern/java/generators/union/UnionTypeSpecGenerator.java

@@ -17,20 +17,23 @@
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Optional;
+import java.util.Set;
 import java.util.stream.Collectors;
 import javax.lang.model.element.Modifier;
 import org.apache.commons.lang3.StringUtils;
 
 public abstract class UnionTypeSpecGenerator {
 
     private static final String VISITOR_CLASS_NAME = "Visitor";
+    private static final String VISITOR_CLASS_NAME_UNDERSCORE = "Visitor_";
     private static final TypeVariableName VISITOR_RETURN_TYPE = TypeVariableName.get("T");
 
     private final ClassName unionClassName;
     private final ClassName valueInterfaceClassName;
     private final List<? extends UnionSubType> subTypes;
     private final UnionSubType unknownSubType;
     private final Constants fernConstants;
+    private final String visitorName;
     private final ParameterizedTypeName visitorInterfaceClassName;
     private final boolean deserializable;
     private final String discriminantProperty;
@@ -41,14 +44,16 @@ public UnionTypeSpecGenerator(
             UnionSubType unknownSubType,
             Constants fernConstants,
             boolean deserializable,
-            String discriminantProperty) {
+            String discriminantProperty,
+            Set<String> reservedTypeNames) {
         this.unionClassName = unionClassName;
         this.subTypes = subTypes;
         this.unknownSubType = unknownSubType;
         this.fernConstants = fernConstants;
         this.valueInterfaceClassName = unionClassName.nestedClass("Value");
+        this.visitorName = visitorName(reservedTypeNames);
         this.visitorInterfaceClassName =
-                ParameterizedTypeName.get(unionClassName.nestedClass(VISITOR_CLASS_NAME), VISITOR_RETURN_TYPE);
+                ParameterizedTypeName.get(unionClassName.nestedClass(visitorName), VISITOR_RETURN_TYPE);
         this.deserializable = deserializable;
         this.discriminantProperty = discriminantProperty;
     }
@@ -170,7 +175,7 @@ private Optional<MethodSpec> getSubTypeMethodSpec(UnionSubType subType) {
     }
 
     public final TypeSpec generateVisitorInterface() {
-        return TypeSpec.interfaceBuilder(VISITOR_CLASS_NAME)
+        return TypeSpec.interfaceBuilder(visitorName)
                 .addModifiers(Modifier.PUBLIC)
                 .addTypeVariable(VISITOR_RETURN_TYPE)
                 .addMethods(subTypes.stream()
@@ -220,4 +225,8 @@ public final ClassName getUnionClassName() {
     public final ClassName getValueInterfaceClassName() {
         return valueInterfaceClassName;
     }
+
+    private static String visitorName(Set<String> reservedTypeNames) {
+        return reservedTypeNames.contains(VISITOR_CLASS_NAME) ? VISITOR_CLASS_NAME_UNDERSCORE : VISITOR_CLASS_NAME;
+    }
 }

generators/java/model/versions.yml

@@ -1,3 +1,10 @@
+- changelogEntry:
+    - summary: |
+        Fix union inline type name conflict resolution.
+      type: fix
+  createdAt: '2025-01-16'
+  irVersion: 53
+  version: 1.4.1
 - changelogEntry:
     - summary: |
         Support inline types in the Java generator.

generators/java/sdk/versions.yml

@@ -1,3 +1,10 @@
+- changelogEntry:
+    - summary: |
+        Fix union inline type name conflict resolution.
+      type: fix
+  createdAt: '2025-01-16'
+  irVersion: 53
+  version: 2.10.1
 - changelogEntry:
     - summary: |
         Support inline types in the Java generator.

generators/java/spring/versions.yml

@@ -1,3 +1,10 @@
+- changelogEntry:
+    - summary: |
+        Fix union inline type name conflict resolution.
+      type: fix
+  createdAt: '2025-01-16'
+  irVersion: 53
+  version: 1.4.1
 - changelogEntry:
     - summary: |
         Support inline types in the Java generator.