Hi, rwxdfbb, thanks for the report.
The parser in our CodeCompletion plugin is not good at parsing template related code, so it failed on the issue your reported.
Two method:
1, make some effort to implement this feature in our parser.
2, use some modern parsers like Clang codecompletion, you can try the ClangCodeCompletion plugin(you need to search the forum to find it, download its source and build it).