Support annotations for 'const'

It was not supported and people use type-level annotations as a
workaround even when the annotations are meant to annotate constants.

  const @Annotation... int foo = 0;

Now we can annotate constants like following.

  @Annotation... const int foo = 0;

Bug: 174436374
Test: aidl_unittests
Change-Id: I5481de6ac48711765fcd7e1726003267360ba9e6

2 files changed, 27 insertions, 4 deletions

diff --git a/aidl_language_y.yy b/aidl_language_y.yy
index 8273815d..64d9f437 100644
--- a/aidl_language_y.yy
+++ b/aidl_language_y.yy
@@ -519,11 +519,18 @@ constant_value_non_empty_list
  ;
 
 constant_decl
- : CONST type identifier '=' const_expr ';' {
-    $2->SetComments($1->GetComments());
-    $$ = new AidlConstantDeclaration(loc(@3), $2, $3->GetText(), $5);
+ : annotation_list CONST type identifier '=' const_expr ';' {
+    if ($1->size() > 0) {
+      $3->SetComments($1->begin()->GetComments());
+    } else {
+      $3->SetComments($2->GetComments());
+    }
+    // TODO(b/151102494) do not merge annotations.
+    $3->Annotate(std::move(*$1));
+    $$ = new AidlConstantDeclaration(loc(@4), $3, $4->GetText(), $6);
     delete $1;
-    delete $3;
+    delete $2;
+    delete $4;
    }
  ;
 
diff --git a/aidl_unittest.cpp b/aidl_unittest.cpp
index 3880f798..4d77f846 100644
--- a/aidl_unittest.cpp
+++ b/aidl_unittest.cpp
@@ -1542,6 +1542,22 @@ TEST_P(AidlTest, UnionWithConstants) {
   EXPECT_EQ("", GetCapturedStderr());
 }
 
+TEST_F(AidlTest, ConstantsWithAnnotations) {
+  io_delegate_.SetFileContents("IFoo.aidl",
+                               "interface IFoo {\n"
+                               " @JavaPassthrough(annotation=\"@Foo\")\n"
+                               " const @JavaPassthrough(annotation=\"@Bar\") int FOO = 0;\n"
+                               "}");
+  Options options = Options::From("aidl IFoo.aidl --lang=java -o out");
+  CaptureStderr();
+  EXPECT_EQ(0, ::android::aidl::compile_aidl(options, io_delegate_));
+  EXPECT_EQ("", GetCapturedStderr());
+  string code;
+  EXPECT_TRUE(io_delegate_.GetWrittenContents("out/IFoo.java", &code));
+  EXPECT_THAT(code, HasSubstr("@Foo\n"));
+  EXPECT_THAT(code, HasSubstr("@Bar\n"));
+}
+
 TEST_F(AidlTest, ApiDump) {
   io_delegate_.SetFileContents(
       "foo/bar/IFoo.aidl",