In @autovalue class Foo<@bar T>, copy @bar to the implementing subclass.

RELNOTES=In @autovalue class Foo<@bar T>, copy @bar to the implementing subclass.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=193530939

Author: eamonnmcmanus

value/src/it/functional/src/test/java/com/google/auto/value/AutoValueJava8Test.java

@@ -34,6 +34,7 @@
 import java.lang.reflect.AnnotatedType;
 import java.lang.reflect.Constructor;
 import java.lang.reflect.Method;
+import java.lang.reflect.TypeVariable;
 import java.util.Arrays;
 import java.util.List;
 import java.util.Set;
@@ -546,4 +547,63 @@ public void testEqualsNullable() throws ReflectiveOperationException {
     assertThat(parameterTypes[0].isAnnotationPresent(EqualsNullable.Nullable.class))
         .isTrue();
   }
+
+  @AutoValue
+  abstract static class AnnotatedTypeParameter<@Nullable T> {
+    abstract @Nullable T thing();
+
+    static <@Nullable T> AnnotatedTypeParameter<T> create(T thing) {
+      return new AutoValue_AutoValueJava8Test_AnnotatedTypeParameter<T>(thing);
+    }
+  }
+
+  /**
+   * Tests that an annotation on a type parameter of an {@code @AutoValue} class is copied to
+   * the implementation class.
+   */
+  @Test
+  public void testTypeAnnotationCopiedToImplementation() throws ReflectiveOperationException {
+    @Nullable String nullableString = "blibby";
+    AnnotatedTypeParameter<@Nullable String> x = AnnotatedTypeParameter.create(nullableString);
+    Class<?> c = x.getClass();
+    assertThat(c.getTypeParameters()).hasLength(1);
+    TypeVariable<?> typeParameter = c.getTypeParameters()[0];
+    assertThat(typeParameter.getAnnotations())
+        .named(typeParameter.toString())
+        .asList()
+        .contains(nullable());
+  }
+
+  @AutoValue
+  abstract static class AnnotatedTypeParameterWithBuilder<@Nullable T> {
+    abstract @Nullable T thing();
+
+    static <@Nullable T> Builder<T> builder() {
+      return new AutoValue_AutoValueJava8Test_AnnotatedTypeParameterWithBuilder.Builder<T>();
+    }
+
+    @AutoValue.Builder
+    abstract static class Builder<@Nullable T> {
+      abstract Builder<T> setThing(T thing);
+      abstract AnnotatedTypeParameterWithBuilder<T> build();
+    }
+  }
+
+  /**
+   * Tests that an annotation on a type parameter of an {@code @AutoValue} builder is copied to
+   * the implementation class.
+   */
+  @Test
+  public void testTypeAnnotationOnBuilderCopiedToImplementation()
+      throws ReflectiveOperationException {
+    AnnotatedTypeParameterWithBuilder.Builder<@Nullable String> builder =
+        AnnotatedTypeParameterWithBuilder.builder();
+    Class<?> c = builder.getClass();
+    assertThat(c.getTypeParameters()).hasLength(1);
+    TypeVariable<?> typeParameter = c.getTypeParameters()[0];
+    assertThat(typeParameter.getAnnotations())
+        .named(typeParameter.toString())
+        .asList()
+        .contains(nullable());
+  }
 }

value/src/main/java/com/google/auto/value/processor/TypeEncoder.java

@@ -162,14 +162,15 @@ static String formalTypeParametersString(TypeElement type) {
       for (TypeParameterElement typeParameter : typeParameters) {
         sb.append(sep);
         sep = ", ";
-        appendTypeParameterWithBounds(sb, typeParameter);
+        appendTypeParameterWithBounds(typeParameter, sb);
       }
       return sb.append(">").toString();
     }
   }
 
   private static void appendTypeParameterWithBounds(
-      StringBuilder sb, TypeParameterElement typeParameter) {
+      TypeParameterElement typeParameter, StringBuilder sb) {
+    appendAnnotations(typeParameter.getAnnotationMirrors(), sb);
     sb.append(typeParameter.getSimpleName());
     String sep = " extends ";
     for (TypeMirror bound : typeParameter.getBounds()) {
@@ -181,6 +182,13 @@ private static void appendTypeParameterWithBounds(
     }
   }
 
+  private static void appendAnnotations(
+      List<? extends AnnotationMirror> annotationMirrors, StringBuilder sb) {
+    for (AnnotationMirror annotationMirror : annotationMirrors) {
+      sb.append(AnnotationOutput.sourceFormForAnnotation(annotationMirror)).append(" ");
+    }
+  }
+
   /**
    * Converts a type into a string, using standard Java syntax, except that every class name
    * is wrapped in backquotes, like {@code `java.util.List`}.
@@ -308,13 +316,6 @@ private static class AnnotatedEncodingTypeVisitor extends EncodingTypeVisitor {
       appendTypeArguments(type, sb);
       return sb;
     }
-
-    private void appendAnnotations(
-        List<? extends AnnotationMirror> annotationMirrors, StringBuilder sb) {
-      for (AnnotationMirror annotationMirror : annotationMirrors) {
-        sb.append(AnnotationOutput.sourceFormForAnnotation(annotationMirror)).append(" ");
-      }
-    }
   }
 
   private static class TypeRewriter {