An enum is initialized as zero if it doesn't have default value

In C++, NDK backend, an enum value hasn't been initialized if it doesn't
have default value. In that case, initialize an enum with zero for the
backends.

Bug: 198346478
Test: check golden output and m
Ignore-AOSP-First: security patch
Change-Id: I6cb67258cc4aacc41ae80c46ccee10a3cfe723f6
Merged-In: I6cb67258cc4aacc41ae80c46ccee10a3cfe723f6
(cherry picked from commit f39b16442ad832f2921ad0eec298b7c333936dc1)

2 files changed, 14 insertions, 0 deletions

diff --git a/generate_cpp.cpp b/generate_cpp.cpp
index cc256573..bbee9b3a 100644
--- a/generate_cpp.cpp
+++ b/generate_cpp.cpp
@@ -1111,6 +1111,13 @@ std::unique_ptr<Document> BuildParcelHeader(const AidlTypenames& typenames,
     if (variable->GetDefaultValue()) {
       out << " = " << cppType.c_str() << "(" << variable->ValueString(ConstantValueDecorator)
           << ")";
+    } else if (auto type = typenames.TryGetDefinedType(variable->GetType().GetName()); type) {
+      if (auto enum_type = type->AsEnumDeclaration(); enum_type) {
+        if (!variable->GetType().IsArray()) {
+          // if an enum doesn't have explicit default value, do zero-initialization
+          out << " = " << cppType << "(0)";
+        }
+      }
     }
     out << ";\n";
 
diff --git a/generate_ndk.cpp b/generate_ndk.cpp
index 274d283f..0efd7eb7 100644
--- a/generate_ndk.cpp
+++ b/generate_ndk.cpp
@@ -879,6 +879,13 @@ void GenerateParcelHeader(CodeWriter& out, const AidlTypenames& types,
     out << NdkNameOf(types, variable->GetType(), StorageMode::STACK) << " " << variable->GetName();
     if (variable->GetDefaultValue()) {
       out << " = " << variable->ValueString(ConstantValueDecorator);
+    } else if (auto type = types.TryGetDefinedType(variable->GetType().GetName()); type) {
+      if (auto enum_type = type->AsEnumDeclaration(); enum_type) {
+        if (!variable->GetType().IsArray()) {
+          // if an enum doesn't have explicit default value, do zero-initialization
+          out << " = " << NdkNameOf(types, variable->GetType(), StorageMode::STACK) << "(0)";
+        }
+      }
     }
     out << ";\n";
   }