Visual Studio Code Intellisense Mode

Because Artemy Vysotsky did not post his answer as an answer:

The documentation states that "msvc-x64" and "clang-x64" are the only possible values.

When editing the .json configuration file, just type "intelliSenseMode": "" and let intelliSense itself help.

Actually you may use the option "intelliSenseMode": "${default}" to allow self selection.

As of today, the defaults are: clang-x64 for Mac; msvc-x64 for Windows; and gcc-x64 for Linux.