Allow trailing comma in lenient mode

build.gradle.kts

@@ -9,10 +9,8 @@ import java.net.URL
 
 buildscript {
   dependencies {
-    val kotlinVersion = System.getenv("MOSHI_KOTLIN_VERSION")
-      ?: libs.versions.kotlin.get()
-    val kspVersion = System.getenv("MOSHI_KSP_VERSION")
-      ?: libs.versions.ksp.get()
+    val kotlinVersion = System.getenv("MOSHI_KOTLIN_VERSION") ?: libs.versions.kotlin.get()
+    val kspVersion = System.getenv("MOSHI_KSP_VERSION") ?: libs.versions.ksp.get()
     classpath(kotlin("gradle-plugin", version = kotlinVersion))
     classpath("com.google.devtools.ksp:symbol-processing-gradle-plugin:$kspVersion")
     // https://github.com/melix/japicmp-gradle-plugin/issues/36

moshi/src/main/java/com/squareup/moshi/ClassJsonAdapter.kt

@@ -55,15 +55,7 @@ internal class ClassJsonAdapter<T>(
   private val options = JsonReader.Options.of(*fieldsMap.keys.toTypedArray())
 
   override fun fromJson(reader: JsonReader): T {
-    val result: T = try {
-      classFactory.newInstance()
-    } catch (e: InstantiationException) {
-      throw RuntimeException(e)
-    } catch (e: InvocationTargetException) {
-      throw e.rethrowCause()
-    } catch (e: IllegalAccessException) {
-      throw AssertionError()
-    }
+    val instance: T = instanciateTargetClass()
 
     try {
       reader.beginObject()
@@ -74,10 +66,22 @@ internal class ClassJsonAdapter<T>(
           reader.skipValue()
           continue
         }
-        fieldsArray[index].read(reader, result)
+        fieldsArray[index].read(reader, instance)
       }
       reader.endObject()
-      return result
+      return instance
+    } catch (e: IllegalAccessException) {
+      throw AssertionError()
+    }
+  }
+
+  private fun instanciateTargetClass(): T {
+    return try {
+      classFactory.newInstance()
+    } catch (e: InstantiationException) {
+      throw RuntimeException(e)
+    } catch (e: InvocationTargetException) {
+      throw e.rethrowCause()
     } catch (e: IllegalAccessException) {
       throw AssertionError()
     }
@@ -96,7 +100,7 @@ internal class ClassJsonAdapter<T>(
     }
   }
 
-  override fun toString() = "JsonAdapter($classFactory)"
+  override fun toString() = "ClassJsonAdapter($classFactory)"
 
   internal class FieldBinding<T>(val name: String, val field: Field, val adapter: JsonAdapter<T>) {
     fun read(reader: JsonReader, value: Any?) {

moshi/src/main/java/com/squareup/moshi/JsonUtf8Reader.kt

@@ -189,7 +189,8 @@ internal class JsonUtf8Reader : JsonReader {
             buffer.readByte() // consume the '}'.
             PEEKED_END_OBJECT
           } else {
-            throw syntaxError("Expected name")
+            checkLenient()
+            PEEKED_END_OBJECT
           }
           else -> {
             checkLenient()

moshi/src/test/java/com/squareup/moshi/JsonAdapterTest.java

@@ -16,6 +16,7 @@
 package com.squareup.moshi;
 
 import static com.google.common.truth.Truth.assertThat;
+import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.fail;
 import static org.junit.Assume.assumeTrue;
 
@@ -26,6 +27,7 @@
 import java.util.Locale;
 import java.util.Map;
 import javax.annotation.Nullable;
+import org.intellij.lang.annotations.Language;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.junit.runners.Parameterized;
@@ -338,4 +340,47 @@ public void nonNullDoesntDuplicate() {
     JsonAdapter<Boolean> adapter = new Moshi.Builder().build().adapter(Boolean.class).nonNull();
     assertThat(adapter.nonNull()).isSameInstanceAs(adapter);
   }
+
+  @Test
+  public void givenJsonWithTrailingComma_whenDeserializeInLenientMode_thenDeserializeSuccessfully()
+      throws IOException {
+    JsonAdapter<Ticket> adapter = new Moshi.Builder().build().adapter(Ticket.class).lenient();
+    @Language("JSON")
+    String json = "{ \"number\" : \"912392\", \"seat\": 1234, \"type\" : \"COMMON\", }";
+    Ticket ticket = adapter.fromJson(json);
+    assertNotNull(ticket);
+    assertThat(ticket.getNumber()).isEqualTo("912392");
+    assertThat(ticket.getSeat()).isEqualTo(1234);
+    assertThat(ticket.getType()).isEqualTo("COMMON");
+  }
+
+  static class Ticket {
+    private String number;
+    private Integer seat;
+    private String type;
+
+    public String getNumber() {
+      return number;
+    }
+
+    public void setNumber(String number) {
+      this.number = number;
+    }
+
+    public Integer getSeat() {
+      return seat;
+    }
+
+    public void setSeat(Integer seat) {
+      this.seat = seat;
+    }
+
+    public String getType() {
+      return type;
+    }
+
+    public void setType(String type) {
+      this.type = type;
+    }
+  }
 }

moshi/src/test/java/com/squareup/moshi/JsonUtf8ReaderTest.java

@@ -39,6 +39,7 @@
 import okio.ForwardingSource;
 import okio.Okio;
 import okio.Source;
+import org.junit.Assert;
 import org.junit.Ignore;
 import org.junit.Test;
 
@@ -1268,9 +1269,10 @@ public void lenientExtraCommasInMaps() throws IOException {
     assertThat(reader.nextName()).isEqualTo("a");
     assertThat(reader.nextString()).isEqualTo("b");
     try {
-      reader.peek();
+      JsonReader.Token peek = reader.peek();
+      Assert.assertEquals(JsonReader.Token.END_OBJECT, peek);
+    } catch (JsonEncodingException unexpected) {
       fail();
-    } catch (JsonEncodingException expected) {
     }
   }