Version 1.22.1 (1.22.1)
I erased all paths to headers from c_cpp_properties.json. Even then IntelliSense gives me a completion suggestions. You can note that I didn't also write any #include.

When I write #include<iostream> then it gives me suggestion from headers I never included.

Os: MacOS High Sierra
c_cpp_properties.json: https://paste.ofcode.org/kbzSrbhAbrdrwiAJp3hbkV
clang: Apple LLVM version 9.1.0 (clang-902.0.39.1)
Version 1.22.1 (1.22.1)
I erased all paths to headers from c_cpp_properties.json. Even then IntelliSense gives me a completion suggestions. You can note that I didn't also write any
#include.When I write
#include<iostream>then it gives me suggestion from headers I never included.Os: MacOS High Sierra
c_cpp_properties.json: https://paste.ofcode.org/kbzSrbhAbrdrwiAJp3hbkV
clang: Apple LLVM version 9.1.0 (clang-902.0.39.1)