Fix #1729. Properly handle type resolving for type parameters.

Author: bennyhuo

moshi-kotlin-codegen/src/main/java/com/squareup/moshi/kotlin/codegen/apt/metadata.kt

@@ -332,7 +332,11 @@ private fun resolveTypeArgs(
 ): TypeName {
   val unwrappedType = propertyType.unwrapTypeAlias()
 
-  if (unwrappedType !is TypeVariableName) {
+  if (unwrappedType is ParameterizedTypeName) {
+    return unwrappedType.copy(typeArguments = unwrappedType.typeArguments.map {
+      resolveTypeArgs(targetClass, it, resolvedTypes, allowedTypeVars, entryStartIndex)
+    })
+  } else if (unwrappedType !is TypeVariableName) {
     return unwrappedType
   } else if (entryStartIndex == -1) {
     return unwrappedType

moshi-kotlin-codegen/src/main/java/com/squareup/moshi/kotlin/codegen/ksp/TargetTypes.kt

@@ -228,7 +228,9 @@ private fun declaredProperties(
   val result = mutableMapOf<String, TargetProperty>()
   for (property in classDecl.getDeclaredProperties()) {
     val initialType = property.type.resolve()
-    val resolvedType = if (initialType.declaration is KSTypeParameter) {
+    val resolvedType = if (initialType.declaration is KSTypeParameter ||
+      initialType.arguments.any { it.type?.resolve()?.declaration is KSTypeParameter }
+    ) {
       property.asMemberOf(originalType.asType())
     } else {
       initialType

moshi-kotlin-codegen/src/test/java/com/squareup/moshi/kotlin/codegen/apt/JsonClassCodegenProcessorTest.kt

@@ -510,6 +510,28 @@ class JsonClassCodegenProcessorTest {
     assertThat(result.messages).contains("JsonQualifier @UpperCase must have RUNTIME retention")
   }
 
+  @Test
+  fun genericSuperClassPropertyTypeSubstitution() {
+    val result = compile(
+      kotlin(
+        "source.kt",
+        """
+          package test
+          import com.squareup.moshi.JsonClass
+
+          open class GenericSuperClass<T> {
+            var t: T? = null
+            var list: List<T>? = null
+          }
+
+          @JsonClass(generateAdapter = true)
+          class SubClassOfGeneric : GenericSuperClass<String>()
+          """,
+      ),
+    )
+    assertThat(result.exitCode).isEqualTo(KotlinCompilation.ExitCode.OK)
+  }
+
   @Test
   fun `TypeAliases with the same backing type should share the same adapter`() {
     val result = compile(

moshi-kotlin-codegen/src/test/java/com/squareup/moshi/kotlin/codegen/ksp/JsonClassSymbolProcessorTest.kt

@@ -557,6 +557,28 @@ class JsonClassSymbolProcessorTest {
     assertThat(result.messages).contains("Error preparing ElementEnvelope")
   }
 
+  @Test
+  fun genericSuperClassPropertyTypeSubstitution() {
+    val result = compile(
+      kotlin(
+        "source.kt",
+        """
+          package test
+          import com.squareup.moshi.JsonClass
+
+          open class GenericSuperClass<T> {
+            var t: T? = null
+            var list: List<T>? = null
+          }
+
+          @JsonClass(generateAdapter = true)
+          class SubClassOfGeneric : GenericSuperClass<String>()
+          """,
+      ),
+    )
+    assertThat(result.exitCode).isEqualTo(KotlinCompilation.ExitCode.OK)
+  }
+
   @Test
   fun `TypeAliases with the same backing type should share the same adapter`() {
     val result = compile(