Generate a trivial dep file for parcelables

It turns out that the SDK tools request this.

This is a cherry-pick of b1bbdf80cb9fcd8181aa2cb326317929cfac890c.

Bug: 28091660
Change-Id: Iba08f116086953d01c0383f4e26049b2ddfe9b29
Test: unittests pass, added another

3 files changed, 32 insertions, 3 deletions

diff --git a/aidl.cpp b/aidl.cpp
index dfe9382e..6f542bfb 100644
--- a/aidl.cpp
+++ b/aidl.cpp
@@ -684,7 +684,9 @@ int compile_aidl_to_java(const JavaOptions& options,
   if (aidl_err == AidlError::FOUND_PARCELABLE && !options.fail_on_parcelable_) {
     // We aborted code generation because this file contains parcelables.
     // However, we were not told to complain if we find parcelables.
-    // Just exit quietly.
+    // Just generate a dep file and exit quietly.  The dep file is for a legacy
+    // use case by the SDK.
+    write_java_dep_file(options, imports, io_delegate, "");
     return 0;
   }
   if (aidl_err != AidlError::OK) {
diff --git a/aidl_unittest.cpp b/aidl_unittest.cpp
index 01a16e17..3375ed97 100644
--- a/aidl_unittest.cpp
+++ b/aidl_unittest.cpp
@@ -48,6 +48,13 @@ R"(place/for/output/p/IFoo.java : \
 p/IFoo.aidl :
 )";
 
+const char kExpectedParcelableDepFileContents[] =
+R"( : \
+  p/Foo.aidl
+
+p/Foo.aidl :
+)";
+
 }  // namespace
 
 class AidlTest : public ::testing::Test {
@@ -300,5 +307,24 @@ TEST_F(AidlTest, WritesCorrectDependencyFile) {
   EXPECT_EQ(actual_dep_file_contents, kExpectedDepFileContents);
 }
 
+TEST_F(AidlTest, WritesTrivialDependencyFileForParcelable) {
+  // The SDK uses aidl to decide whether a .aidl file is a parcelable.  It does
+  // this by calling aidl with every .aidl file it finds, then parsing the
+  // generated dependency files.  Those that reference .java output files are
+  // for interfaces and those that do not are parcelables.  However, for both
+  // parcelables and interfaces, we *must* generate a non-empty dependency file.
+  JavaOptions options;
+  options.input_file_name_ = "p/Foo.aidl";
+  options.output_base_folder_ = "place/for/output";
+  options.dep_file_name_ = "dep/file/path";
+  io_delegate_.SetFileContents(options.input_file_name_,
+                               "package p; parcelable Foo;");
+  EXPECT_EQ(0, ::android::aidl::compile_aidl_to_java(options, io_delegate_));
+  string actual_dep_file_contents;
+  EXPECT_TRUE(io_delegate_.GetWrittenContents(options.dep_file_name_,
+                                              &actual_dep_file_contents));
+  EXPECT_EQ(actual_dep_file_contents, kExpectedParcelableDepFileContents);
+}
+
 }  // namespace aidl
 }  // namespace android
diff --git a/options.h b/options.h
index dd64f7e3..6f32c62a 100644
--- a/options.h
+++ b/options.h
@@ -1,6 +1,5 @@
 /*
- * Copyright (C) 2015, The Android Open Source Project
- *
+ * Copyright (C) 2015, The Android Open Source Project *
  * 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
@@ -62,6 +61,8 @@ class JavaOptions final {
   FRIEND_TEST(AidlTest, FailOnParcelable);
   FRIEND_TEST(AidlTest, WritePreprocessedFile);
   FRIEND_TEST(AidlTest, WritesCorrectDependencyFile);
+  FRIEND_TEST(AidlTest, WritesTrivialDependencyFileForParcelable);
+
   DISALLOW_COPY_AND_ASSIGN(JavaOptions);
 };