Raw string with curly braces

[alexr00]

Checklist

• [x ] This problem exists even with the setting "C_Cpp.enhancedColorization": "Disabled"

If Disabling that^ makes the problem go away, then follow this to make an issue on the C++ extension:
https://github.com/microsoft/vscode-cpptools/issues/new/choose

The code with a problem is:

enum class ID_STRINGS_EXT : int {
    SERVER_LISTENING = ID_UNUSED_STRING(
        R"(Server is listening :\n\t{})"
        "hello world"),
    INVALID_ARGUMENT = ID_UNUSED_STRING("Invalid Argument"),
    NOT_FOUND        = ID_UNUSED_STRING("Not Found")
};

It looks like:

It should look like:

Removing the curly braces in the raw string resolves the issue.

Originally from @guoiaoang in microsoft/vscode#299789