How do I get CMake Tools to compile programs in Visual Studio Code with C++11 (or higher) features?

I'm new to CMake in general so hopefully there is something simple I'm doing wrong but I'm pulling my hair out trying to find the solution. I can't get CMake tools to compile even a trivial program with c++11 (or higher features). Ideally I'd like to enable c++17.

For example, if my entire main() function is

int main(int, char**) 
{
    auto number{9};

    return 0;
}

I get the following 2 errors and 1 warning when attempting a build:

error: declaration of variable 'number' with deduced type 'auto' requires an initializer

error: expected ';' at end of declaration

warning: 'auto' type specifier is a C++11 extension [-Wc++11-extensions]

My VSCode C++ settings are set to the C++17 standard, and I don't get any Intellisense errors or warnings when writing the code, just when I try to build using the CMake Tools extension.

I've also tried adding the following to my CMakeLists.txt file:

set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED ON)
set(CMAKE_CXX_EXTENSIONS OFF)

What am I missing? Thanks very much!

Platform and Versions

Operating System: macOS High Sierra 10.13.6

CMake Version: 3.16.2

VSCode Version: 1.41.1

CMake Tools Extension Version: 1.2.3

Compiler/Toolchain: Clang 10.0.0