Make package parsing code consume annotations am: 2863e4535e

Original change: https://android-review.googlesource.com/c/platform/build/soong/+/2760406

Change-Id: I6441efbe49bd65f72d952bc8d65519dd2a286952
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>

jar/jar.go

@@ -166,10 +166,23 @@ func JavaPackage(r io.Reader, src string) (string, error) {
 	}
 	s.IsIdentRune = javaIdentRune
 
-	tok := s.Scan()
+	var tok rune
+	for {
+		tok = s.Scan()
 		if sErr != nil {
 			return "", sErr
 		}
+		// If the first token is an annotation, it could be annotating a package declaration, so consume them.
+		// Note that this does not support "complex" annotations with attributes, e.g. @Foo(x=y).
+		if tok != '@' {
+			break
+		}
+		tok = s.Scan()
+		if tok != scanner.Ident || sErr != nil {
+			return "", fmt.Errorf("expected annotation identifier, got @%v", tok)
+		}
+	}
+
 	if tok == scanner.Ident {
 		switch s.TokenText() {
 		case "package":
@@ -189,9 +202,6 @@ func JavaPackage(r io.Reader, src string) (string, error) {
 		default:
 			return "", fmt.Errorf(`expected first token of java file to be "package", got %q`, s.TokenText())
 		}
-	} else if tok == '@' {
-		// File has no package statement, first token is an annotation
-		return "", nil
 	} else if tok == scanner.EOF {
 		// File no package statement, it has no non-whitespace non-comment tokens
 		return "", nil

jar/jar_test.go

@@ -61,6 +61,16 @@ func TestGetJavaPackage(t *testing.T) {
 			in:      "package 0foo.bar;",
 			wantErr: true,
 		},
+		{
+			name: "annotations",
+			in:   "@NonNullApi\n@X\npackage foo.bar;",
+			want: "foo.bar",
+		},
+		{
+			name:    "complex annotation",
+			in:      "@Foo(x=y)\n@package foo.bar;",
+			wantErr: true, // Complex annotation not supported yet.
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {