Various issue with gcc-13 due to unchecked __is_convertible built-in in system headers (is_convertible_v)

[felix-leg]

Environment

• OS and Version: Linux 6.3.5-zen1-1-zen
• VS Code Version: April 2023 (version 1.78)
• C/C++ Extension Version: v1.16.0

Bug Summary and Steps to Reproduce

Bug Summary:
Intellisense marks a correct C++20 code with the error no != operator matches these operands .

Steps to reproduce:

1. Enter the below code:

#include <iostream>
#include <string>

int main (int argc, char **argv)
{
    std::string str = "Hello";
    for(auto c : str) {}
    return 0;
}

2. Wait for Intellisense to catch up
3. Intellisense highlights the for loop with error:

[{
	"owner": "C/C++: IntelliSense",
	"code": "349",
	"severity": 8,
	"message": "no \"!=\" operator matches these operands",
	"source": "C/C++",
	"relatedInformation": [
		{
			"message": "operand types: __gnu_cxx::__normal_iterator<const char *, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>> != __gnu_cxx::__normal_iterator<const char *, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>>"
		}
	]
}]

Expected behavior:

Intellisense shouldn't highlight the code

Configuration and Logs

c_cpp_properties.json:

{
    "configurations": [
        {
            "name": "Linux",
            "includePath": [
                "${workspaceFolder}/src"
            ],
            "defines": [
            ],
            "compilerPath": "/usr/bin/gcc",
            "cStandard": "gnu11",
            "cppStandard": "c++20",
            "intelliSenseMode": "gcc-x64",
            "configurationProvider": "ms-vscode.cmake-tools",
            "compileCommands": "${workspaceFolder}/build/compile_commands.json"
        }
    ],
    "version": 4
}

Diagnostics:

-------- Diagnostics - 1.06.2023, 14:04:23
Version: 1.16.0
Current Configuration:
{
    "name": "Linux",
    "includePath": [
        ".../src"
    ],
    "defines": [
    ],
    "compilerPath": "/usr/bin/gcc",
    "cStandard": "gnu11",
    "cppStandard": "c++20",
    "intelliSenseMode": "gcc-x64",
    "configurationProvider": "ms-vscode.cmake-tools",
    "compileCommands": ".../build/compile_commands.json",
    "compilerPathIsExplicit": true,
    "cStandardIsExplicit": true,
    "cppStandardIsExplicit": true,
    "intelliSenseModeIsExplicit": true,
    "compilerPathInCppPropertiesJson": "/usr/bin/gcc",
    "compileCommandsInCppPropertiesJson": "${workspaceFolder}/build/compile_commands.json",
    "configurationProviderInCppPropertiesJson": "ms-vscode.cmake-tools",
    "mergeConfigurations": false,
    "browse": {
        "path": [
            "${workspaceFolder}/src",
            "${workspaceFolder}"
        ],
        "limitSymbolsToIncludedHeaders": true
    }
}
Custom browse configuration: 
{
    "browsePath": [
        ".../src/file_types/json",
        ".../src/utility",
        ".../src",
        ".../src/system/sdl_low",
        ".../system/gl"
    ],
    "compilerPath": "/usr/bin/c++",
    "compilerArgs": [],
    "compilerFragments": [
        "-g -std=c++20"
    ]
}
Custom configurations:
[ .../src/file_types/json/lexer.cpp ]
{
    "includePath": [],
    "defines": [],
    "compilerPath": "/usr/bin/c++",
    "compilerArgs": [],
    "compilerFragments": [
        "-g -std=c++20"
    ]
}
Translation Unit Mappings:
[ .../src/file_types/json/lexer.cpp ]:
    .../src/file_types/json/lexer.cpp
Translation Unit Configurations:
[ .../src/file_types/json/lexer.cpp ]:
    Process ID: 24337
    Memory Usage: 299 MB
    Compiler Path: /usr/bin/c++
    Includes:
        /usr/include/c++/13.1.1
        /usr/include/c++/13.1.1/x86_64-pc-linux-gnu
        /usr/include/c++/13.1.1/backward
        /usr/lib/gcc/x86_64-pc-linux-gnu/13.1.1/include
        /usr/local/include
        /usr/lib/gcc/x86_64-pc-linux-gnu/13.1.1/include-fixed
        /usr/include
    Standard Version: c++20
    IntelliSense Mode: linux-gcc-x64
    Other Flags:
        --g++
        --gnu_version=130101
Total Memory Usage: 299 MB
Browse Paths from compile_commands.json, from workspace folder: ...
    .../src
    .../src/file_types/json
    .../src/system/gl
    .../src/system/sdl_low
    .../src/utility

------- Workspace parsing diagnostics -------
Number of files discovered (not excluded): 55664
Number of files parsed: 6369

Other Extensions

No response

Additional context

No response

[Colengms]

Hi @felix-leg . Thanks for reporting this. It looks like some recent changes in gcc (13) headers have exposed some IntelliSense issues.

[Colengms]

It looks like this can be narrowed down to the following repro:

static_assert(std::is_convertible_v<int, int>);

This may be a gcc-13 header bug. In most places, the gcc 13 system headers are using __has_builtin to ensure certain compiler built-ins are supported before relying on them. But, for is_convertible_v, it's leveraging their new built-in without that check.

Though, it may also be possible for us to address in the C/C++ Extension by adding support for new gcc 13 built-ins.

[michelleangela]

Fix available in pre-release https://github.com/microsoft/vscode-cpptools/releases/tag/v1.17.0.

[michelleangela]

Fixed in release version https://github.com/microsoft/vscode-cpptools/releases/tag/v1.17.2.