Default cStandard is incorrectly c11 instead of gnu18 when the default compiler is gcc

[minecraft2048]

Type: LanguageService

Describe the bug

• OS and Version: Ubuntu 20.04 LTS
• VS Code Version:Version: 1.46.1
• C/C++ Extension Version: v0.29.0
• CRTSCTS from termios.h is squiggled with identifier "CRTSCTS" is undefined but it can compile on gcc without any problems

Steps to reproduce

1. Enter this source file:

#include <stdio.h>
#include <stdlib.h>
#include <termios.h>

struct termios tty;
int main(){
    tty.c_cflag &= ~CRTSCTS;
    printf("hello");
}

2. Try compiling the code with gcc -o test2 test2.c and observe that the code compiles and run just fine
3. CRTSCTS is squiggled with identifier "CRTSCTS" is undefined but that code can compile in gcc just fine

Expected behavior

CRTSCTS is not squiggled

Logs

Log Diagnostics: https://gist.github.com/minecraft2048/764f72423659df3c1c33c8b21c4136d0
Language server log: https://gist.github.com/minecraft2048/70006e0791459f875d40dc47a1876a6e

[sean-mcmanus]

Change your cStandard property to gnu11 to fix the issue

            "cStandard": "gnu11",

Let us know if you think there's a bug with the default cStandard not being set correctly (I think it should be gnu11 by default if we detect a gcc compiler by default).

[sean-mcmanus]

Yeah, I just reproed a bug where cStandard is being set to c11 by default instead of gnu11 (cppStandard is correctly gnu++14).

[sean-mcmanus]

The bug repros when the compiler reports __STDC_VERSION__ 201710L. Should be trivial to fix. The default of gnu18 should be used (we were only handling the case where the compiler reported a 2018 version).

[sean-mcmanus]

Fixed with https://github.com/microsoft/vscode-cpptools/releases/tag/0.30.0-insiders .