Fix type inference issues with generated assisted factory in Java 7.

To test this, I've updated our gradle use sourceCompatibility = VERSION_1_7.

Fixes #2309

RELNOTES=Fixes #2309: Fixes type inference issues with generated assisted factory in Java 7.
PiperOrigin-RevId: 354533035

java/dagger/internal/codegen/AssistedFactoryProcessingStep.java

@@ -305,8 +305,9 @@ public Element originatingElement(ProvisionBinding binding) {
     public Optional<TypeSpec.Builder> write(ProvisionBinding binding) {
       TypeElement factory = asType(binding.bindingElement().get());
 
+      ClassName name = nameGeneratedType(binding);
       TypeSpec.Builder builder =
-          TypeSpec.classBuilder(nameGeneratedType(binding))
+          TypeSpec.classBuilder(name)
               .addModifiers(PUBLIC, FINAL)
               .addTypeVariables(
                   factory.getTypeParameters().stream()
@@ -357,9 +358,13 @@ public Optional<TypeSpec.Builder> write(ProvisionBinding binding) {
                           .collect(toImmutableList()))
                   .returns(providerOf(TypeName.get(factory.asType())))
                   .addStatement(
-                      "return $T.create(new $T($N))",
+                      "return $T.$Lcreate(new $T($N))",
                       INSTANCE_FACTORY,
-                      nameGeneratedType(binding),
+                      // Java 7 type inference requires the method call provide the exact type here.
+                      sourceVersion.compareTo(SourceVersion.RELEASE_7) <= 0
+                          ? CodeBlock.of("<$T>", types.accessibleType(factoryType, name))
+                          : CodeBlock.of(""),
+                      name,
                       delegateFactoryParam)
                   .build());
       return Optional.of(builder);

javatests/artifacts/dagger/simple/build.gradle

@@ -24,17 +24,14 @@ repositories {
   mavenLocal()
 }
 
-sourceSets {
-  main {
-    java {
-      srcDir '.'
-    }
-  }
+java {
+    // Make sure the generated source is compatible with Java 7.
+    sourceCompatibility = JavaVersion.VERSION_1_7
 }
 
 dependencies {
   implementation 'com.google.dagger:dagger:LOCAL-SNAPSHOT'
   annotationProcessor 'com.google.dagger:dagger-compiler:LOCAL-SNAPSHOT'
 }
 
-mainClassName = 'dagger.example.gradle.simple.SimpleApplication'
+mainClassName = 'dagger.simple.SimpleApplication'

javatests/artifacts/dagger/simple/src/main/java/dagger/simple/AssistedInjects.java

@@ -0,0 +1,66 @@
+/*
+ * Copyright (C) 2021 The Dagger Authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package dagger.simple;
+
+import dagger.Component;
+import dagger.assisted.Assisted;
+import dagger.assisted.AssistedFactory;
+import dagger.assisted.AssistedInject;
+import javax.inject.Inject;
+
+// This is a regression test for https://github.com/google/dagger/issues/2309
+/** A simple, skeletal application that defines an assisted inject binding. */
+public class AssistedInjects {
+  @Component
+  interface MyComponent {
+    FooFactory fooFactory();
+
+    ParameterizedFooFactory<Bar, String> parameterizedFooFactory();
+  }
+
+  static final class Bar {
+    @Inject
+    Bar() {}
+  }
+
+  static class Foo {
+    @AssistedInject
+    Foo(Bar bar, @Assisted String str) {}
+  }
+
+  @AssistedFactory
+  interface FooFactory {
+    Foo create(String str);
+  }
+
+  static class ParameterizedFoo<T1, T2> {
+    @AssistedInject
+    ParameterizedFoo(T1 t1, @Assisted T2 t2) {}
+  }
+
+  @AssistedFactory
+  interface ParameterizedFooFactory<T1, T2> {
+    ParameterizedFoo<T1, T2> create(T2 t2);
+  }
+
+  public static void main(String[] args) {
+    Foo foo = DaggerAssistedInjects_MyComponent.create().fooFactory().create("");
+
+    ParameterizedFoo<Bar, String> parameterizedFoo =
+        DaggerAssistedInjects_MyComponent.create().parameterizedFooFactory().create("");
+  }
+}

javatests/artifacts/dagger/simple/SimpleApplication.java → javatests/artifacts/dagger/simple/src/main/java/dagger/simple/SimpleApplication.java

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package dagger.example.gradle.simple;
+package dagger.simple;
 
 import dagger.Component;
 import dagger.Module;