From 7e2924a729a14cc2443767d402eafc67c2f90b14 Mon Sep 17 00:00:00 2001
From: Eliezer Graber <me@eygraber.com>
Date: Fri, 22 Nov 2024 01:48:25 -0500
Subject: [PATCH] Handle typealias to typealias

---
 .../me/tatarka/inject/test/TypeAliasTest.kt   | 29 +++++++++++++++++++
 .../me/tatarka/inject/test/TypeAlias.kt       | 28 ++++++++++++++++++
 .../inject/compiler/TypeResultResolver.kt     |  4 ++-
 .../kotlin/me/tatarka/inject/compiler/Util.kt | 12 +++++++-
 4 files changed, 71 insertions(+), 2 deletions(-)
 create mode 100644 integration-tests/common-test/src/test/kotlin/me/tatarka/inject/test/TypeAliasTest.kt
 create mode 100644 integration-tests/common/src/main/kotlin/me/tatarka/inject/test/TypeAlias.kt

diff --git a/integration-tests/common-test/src/test/kotlin/me/tatarka/inject/test/TypeAliasTest.kt b/integration-tests/common-test/src/test/kotlin/me/tatarka/inject/test/TypeAliasTest.kt
new file mode 100644
index 00000000..1bd3dd74
--- /dev/null
+++ b/integration-tests/common-test/src/test/kotlin/me/tatarka/inject/test/TypeAliasTest.kt
@@ -0,0 +1,29 @@
+package me.tatarka.inject.test
+
+import assertk.assertThat
+import assertk.assertions.isNotNull
+import kotlin.test.Test
+
+class TypeAliasTest {
+
+    @Test
+    fun can_generate_for_typealias_on_typealias_function() {
+        val component = TypeAliasesComponent::class.create()
+
+        assertThat(component.typeAliasFoo()).isNotNull()
+    }
+
+    @Test
+    fun can_generate_for_typealias_on_typealias_to_typealias_function() {
+        val component = TypeAliasesComponent::class.create()
+
+        assertThat(component.typeAliasToTypeAliasFoo()).isNotNull()
+    }
+
+    @Test
+    fun can_generate_for_typealias_on_typealias_to_typealias_to_typealias_function() {
+        val component = TypeAliasesComponent::class.create()
+
+        assertThat(component.typeAliasToTypeAliasToTypeAliasFoo()).isNotNull()
+    }
+}
diff --git a/integration-tests/common/src/main/kotlin/me/tatarka/inject/test/TypeAlias.kt b/integration-tests/common/src/main/kotlin/me/tatarka/inject/test/TypeAlias.kt
new file mode 100644
index 00000000..01fa71f9
--- /dev/null
+++ b/integration-tests/common/src/main/kotlin/me/tatarka/inject/test/TypeAlias.kt
@@ -0,0 +1,28 @@
+package me.tatarka.inject.test
+
+import me.tatarka.inject.annotations.Component
+import me.tatarka.inject.annotations.Inject
+
+@Inject
+class TypeAliasBar
+
+typealias TypeAliasToTypeAliasBar = TypeAliasBar
+typealias TypeAliasToTypeAliasToTypeAliasBar = TypeAliasToTypeAliasBar
+
+@Inject
+fun TypeAliasFoo(
+    bar: TypeAliasBar,
+    typeAliasToBar: TypeAliasToTypeAliasBar,
+    typeAliasToTypeAliasToBar: TypeAliasToTypeAliasToTypeAliasBar,
+) {}
+typealias TypeAliasFoo = () -> Unit
+
+typealias TypeAliasToTypeAliasFoo = TypeAliasFoo
+typealias TypeAliasToTypeAliasToTypeAliasFoo = TypeAliasToTypeAliasFoo
+
+@Component
+abstract class TypeAliasesComponent {
+    abstract fun typeAliasFoo(): TypeAliasFoo
+    abstract fun typeAliasToTypeAliasFoo(): TypeAliasToTypeAliasFoo
+    abstract fun typeAliasToTypeAliasToTypeAliasFoo(): TypeAliasToTypeAliasToTypeAliasFoo
+}
diff --git a/kotlin-inject-compiler/core/src/main/kotlin/me/tatarka/inject/compiler/TypeResultResolver.kt b/kotlin-inject-compiler/core/src/main/kotlin/me/tatarka/inject/compiler/TypeResultResolver.kt
index d9a9e80a..32ad1ccf 100644
--- a/kotlin-inject-compiler/core/src/main/kotlin/me/tatarka/inject/compiler/TypeResultResolver.kt
+++ b/kotlin-inject-compiler/core/src/main/kotlin/me/tatarka/inject/compiler/TypeResultResolver.kt
@@ -382,8 +382,10 @@ class TypeResultResolver(private val provider: AstProvider, private val options:
         val resolveType = key.type.resolvedType()
         val args = resolveType.arguments.dropLast(1)
         if (key.type.isTypeAlias()) {
+            val resolvedTypeAlias = key.type.resolveToHighestTypeAlias()
+
             // Check to see if we have a function matching the type alias
-            val functions = provider.findFunctions(key.type.packageName, key.type.simpleName)
+            val functions = provider.findFunctions(resolvedTypeAlias.packageName, resolvedTypeAlias.simpleName)
             val injectedFunction = functions.find { it.isInject() }
             if (injectedFunction != null) {
                 return NamedFunction(
diff --git a/kotlin-inject-compiler/core/src/main/kotlin/me/tatarka/inject/compiler/Util.kt b/kotlin-inject-compiler/core/src/main/kotlin/me/tatarka/inject/compiler/Util.kt
index 7fce2a3c..842e22b4 100644
--- a/kotlin-inject-compiler/core/src/main/kotlin/me/tatarka/inject/compiler/Util.kt
+++ b/kotlin-inject-compiler/core/src/main/kotlin/me/tatarka/inject/compiler/Util.kt
@@ -73,4 +73,14 @@ private fun <T> renderTree(node: T, visitor: TreeVisitor<T>, indent: String, isL
 fun AstType.isSet(): Boolean = packageName == "kotlin.collections" && simpleName == "Set"
 fun AstType.isMap(): Boolean = packageName == "kotlin.collections" && simpleName == "Map"
 fun AstType.isPair(): Boolean = packageName == "kotlin" && simpleName == "Pair"
-fun AstType.isFunctionOrTypeAliasOfFunction() = isFunction() || isTypeAlias() && resolvedType().isFunction()
+fun AstType.isFunctionOrTypeAliasOfFunction(): Boolean = isFunction() || isTypeAlias() &&
+    resolvedType().isFunctionOrTypeAliasOfFunction()
+
+tailrec fun AstType.resolveToHighestTypeAlias(): AstType {
+    check(isTypeAlias()) {
+        "resolveToHighestTypeAlias should only be called on a typealias AstType"
+    }
+
+    val resolvedType = resolvedType()
+    return if (resolvedType.isTypeAlias()) resolvedType.resolveToHighestTypeAlias() else this
+}