Ban @Inject protected field.

RELNOTES=Ban @Inject protected field.
PiperOrigin-RevId: 595746282

java/dagger/internal/codegen/validation/InjectValidator.java

@@ -64,6 +64,7 @@
  */
 @Singleton
 public final class InjectValidator implements ClearableCache {
+
   private final XProcessingEnv processingEnv;
   private final CompilerOptions compilerOptions;
   private final DependencyRequestValidator dependencyRequestValidator;
@@ -298,6 +299,15 @@ private ValidationReport validateField(XFieldElement fieldElement) {
           fieldElement);
     }
 
+    if (fieldElement.isProtected()
+        && fieldElement.getEnclosingElement().isFromKotlin()
+        ) {
+      builder.addItem(
+          "Dagger injector does not have access to kotlin protected fields",
+          staticMemberDiagnosticKind(),
+          fieldElement);
+    }
+
     validateDependencyRequest(builder, fieldElement);
 
     return builder.build();

javatests/dagger/internal/codegen/MembersInjectionTest.java

@@ -45,6 +45,88 @@ public MembersInjectionTest(CompilerMode compilerMode) {
     this.compilerMode = compilerMode;
   }
 
+  @Test
+  public void injectKotlinProtectField_fails() {
+    Source injectFieldSrc =
+        CompilerTests.kotlinSource(
+            "MyClass.kt",
+            "package test",
+            "",
+            "import javax.inject.Inject",
+            "",
+            "class MyClass @Inject constructor() {",
+            "  @Inject protected lateinit var protectedField: String",
+            "}");
+    Source moduleSrc =
+        CompilerTests.kotlinSource(
+            "MyModule.kt",
+            "package test",
+            "",
+            "import dagger.Module",
+            "import dagger.Provides",
+            "",
+            "@Module",
+            "object MyModule {",
+            "  @Provides",
+            "  fun providesString() = \"hello\"",
+            "}");
+    Source componentSrc =
+        CompilerTests.kotlinSource(
+            "MyComponent.kt",
+            "package test",
+            "",
+            "import dagger.Component",
+            "@Component(modules = [MyModule::class])",
+            "interface MyComponent {}");
+    CompilerTests.daggerCompiler(injectFieldSrc, moduleSrc, componentSrc)
+        .withProcessingOptions(compilerMode.processorOptions())
+        .compile(
+            subject -> {
+              subject.hasErrorCount(1);
+              subject.hasErrorContaining(
+                  "Dagger injector does not have access to kotlin protected fields");
+            });
+  }
+
+  @Test
+  public void injectJavaProtectField_succeeds() {
+    Source injectFieldSrc =
+        CompilerTests.javaSource(
+            "test.MyClass",
+            "package test;",
+            "",
+            "import javax.inject.Inject;",
+            "",
+            "public final class MyClass {",
+            "  @Inject MyClass() {}",
+            "  @Inject protected String protectedField;",
+            "}");
+    Source moduleSrc =
+        CompilerTests.kotlinSource(
+            "MyModule.kt",
+            "package test",
+            "",
+            "import dagger.Module",
+            "import dagger.Provides",
+            "",
+            "@Module",
+            "object MyModule {",
+            "  @Provides",
+            "  fun providesString() = \"hello\"",
+            "}");
+    Source componentSrc =
+        CompilerTests.kotlinSource(
+            "MyComponent.kt",
+            "package test",
+            "",
+            "import dagger.Component",
+            "@Component(modules = [MyModule::class])",
+            "interface MyComponent {}");
+    CompilerTests.daggerCompiler(injectFieldSrc, moduleSrc, componentSrc)
+        .withProcessingOptions(compilerMode.processorOptions())
+        .compile(subject -> subject.hasErrorCount(0));
+  }
+
   @Test
   public void parentClass_noInjectedMembers() throws Exception {
     Source childFile =
@@ -159,7 +241,8 @@ public void parentClass_injectedMembersInSupertype() throws Exception {
         .compile(
             subject -> {
               subject.hasErrorCount(0);
-              subject.generatedSource(goldenFileRule.goldenSource("test/GenericClass_MembersInjector"));
+              subject.generatedSource(
+                  goldenFileRule.goldenSource("test/GenericClass_MembersInjector"));
             });
   }