Fix complex alias handling in KsTypes (#1929)

docs/changelog.md

@@ -5,6 +5,7 @@ Change Log
 
 * **Fix**: Don't expand typealiases of function types to `LambdaTypeName`s in `KSTypeReference.toTypeName()`.
 * **Fix**: Small double and float values were set to 0.0 in %L translation (#1919)
+* **Fix**: Fix typealias type argument resolution in KSP2.
 * **Enhancement**: Make enum entry references in `KSAnnotation.toAnnotationSpec()` and `KSClassDeclaration.toClassName()` more robust.
 * Migrate `kotlinpoet-metadata` to stable `org.jetbrains.kotlin:kotlin-metadata-jvm` artifact for Metadata parsing.
 * Promote `kotlinpoet-metadata` out of preview to stable.

interop/ksp/src/main/kotlin/com/squareup/kotlinpoet/ksp/KsTypes.kt

@@ -199,6 +199,6 @@ public fun KSTypeReference.toTypeName(
       returnType = elem.returnType.toTypeName(typeParamResolver),
     ).copy(nullable = type.isMarkedNullable, suspending = type.isSuspendFunctionType)
   } else {
-    type.toTypeName(typeParamResolver, element?.typeArguments.orEmpty())
+    type.toTypeName(typeParamResolver, type.arguments)
   }
 }

interop/ksp/test-processor/src/test/kotlin/com/squareup/kotlinpoet/ksp/test/processor/TestProcessorTest.kt

@@ -911,6 +911,49 @@ class TestProcessorTest(private val useKsp2: Boolean) {
     )
   }
 
+  @Test
+  fun complexAliasing() {
+    val compilation = prepareCompilation(
+      kotlin(
+        "Example.kt",
+        """
+           package test
+
+           import javax.inject.Provider
+           import com.squareup.kotlinpoet.ksp.test.processor.ExampleAnnotation
+
+           typealias DaggerProvider<T> = @JvmSuppressWildcards Provider<T>
+           interface SelectOptions
+           interface SelectHandler<T>
+
+           @ExampleAnnotation
+           class Example(
+             private val handlers: Map<Class<out SelectOptions>, DaggerProvider<SelectHandler<*>>>,
+           )
+           """,
+      ),
+    )
+
+    val result = compilation.compile()
+    assertThat(result.exitCode).isEqualTo(KotlinCompilation.ExitCode.OK)
+    val generatedFileText = File(compilation.kspSourcesDir, "kotlin/test/TestExample.kt")
+      .readText()
+
+    assertThat(generatedFileText).isEqualTo(
+      """
+        package test
+
+        import java.lang.Class
+        import kotlin.collections.Map
+
+        public class TestExample {
+          private val handlers: Map<Class<out SelectOptions>, DaggerProvider<SelectHandler<*>>> = TODO()
+        }
+
+      """.trimIndent(),
+    )
+  }
+
   private fun prepareCompilation(vararg sourceFiles: SourceFile): KotlinCompilation {
     return KotlinCompilation()
       .apply {