cpptools insiders (0.29.0) Segmentation fault (With simple reproduction code) - std::rotate, C++20, Linux, Clang

[olekolek1000]

Type: LanguageService

• OS and Version: Linux x64
• VS Code Version: 1.47.0-insiders
• C/C++ Extension Version: 0.29.0-insiders

cpptools-srv crashes instantly after typing C++ code below (C++20 mode):

#include <vector>
#include <iostream>
#include <algorithm>
 
int main()
{
    std::vector<int> v{2, 4, 2, 0, 5, 10, 7, 3, 7, 1}; 
 
    std::cout << "before sort:      ";
    for (int n: v)
        std::cout << n << ' ';
    std::cout << '\n';
 
    // insertion sort
    for (auto i = v.begin(); i != v.end(); ++i) {
        std::rotate(std::upper_bound(v.begin(), i, *i), i, i+1);
    }
 
    std::cout << "after sort:       ";
    for (int n: v)
        std::cout << n << ' ';
    std::cout << '\n';
 
    // simple rotation to the left
    std::rotate(v.begin(), v.begin() + 1, v.end());
 
    std::cout << "simple rotate left  : ";
    for (int n: v)
        std::cout << n << ' ';
    std::cout << '\n';
 
    // simple rotation to the right
    std::rotate(v.rbegin(), v.rbegin() + 1, v.rend());
 
    std::cout << "simple rotate right : ";
    for (int n: v)
        std::cout << n << ' ';
    std::cout << '\n';
 
}

(example code from cppreference.com):
https://en.cppreference.com/w/cpp/algorithm/rotate

Steps to reproduce

1. Copy example code from https://en.cppreference.com/w/cpp/algorithm/rotate at the bottom
2. Run intellisense (Enable C++20 in .vscode/c_cpp_properties.json)
3. Segmentation fault.

Logs from the command `C/C++: Log Diagnostics

-------- Diagnostics - 06/07/2020, 14:24:20
Version: 0.29.0-insiders
Current Configuration:
{
    "name": "Linux",
    "includePath": [],
    "cppStandard": "c++20",
    "compilerArgs": [],
    "cStandard": "c11",
    "intelliSenseMode": "gcc-x64",
    "browse": {
        "path": [
            "${workspaceFolder}"
        ],
        "limitSymbolsToIncludedHeaders": true
    }
}
Translation Unit Mappings:
[ /home/XXXXXX/Desktop/repro/main.cpp ]:
    /home/XXXXXX/Desktop/repro/main.cpp
Translation Unit Configurations:
[ /home/XXXXXX/Desktop/repro/main.cpp ]: not ready
    Process ID: 33716
    Memory Usage: 0 MB
    Compiler Path: /usr/bin/clang
    Includes:
        /usr/include/c++/10.1.0
        /usr/include/c++/10.1.0/x86_64-pc-linux-gnu
        /usr/include/c++/10.1.0/backward
        /usr/local/include
        /usr/lib/clang/10.0.0/include
        /include
        /usr/include
    Standard Version: c++20
    IntelliSense Mode: clang-x64
    Other Flags:
        --clang
        --clang_version=100000
Total Memory Usage: 0 MB

Logs from the language server:

sending compilation args for /home/XXXXX/Desktop/repro/main.cpp
  include: /usr/include/c++/10.1.0
  include: /usr/include/c++/10.1.0/x86_64-pc-linux-gnu
  include: /usr/include/c++/10.1.0/backward
  include: /usr/local/include
  include: /usr/lib/clang/10.0.0/include
  include: /include
  include: /usr/include
  define: __llvm__=1
  define: __clang__=1
.........a lot of defines..........
other: --clang
  other: --clang_version=100000
  stdver: c++20
  intelliSenseMode: clang-x64
Checking for syntax errors: file:///home/XXXXXX/Desktop/repro/main.cpp
Queueing IntelliSense update for files in translation unit of: /home/XXXXXX/Desktop/repro/main.cpp
cpptools/getDocumentSymbols: file:///home/XXXXXX/Desktop/repro/main.cpp (id: 4)
  Processing folder (recursive): /usr/local/include/
  Processing folder (recursive): /usr/lib/clang/10.0.0/include/
  Processing folder (recursive): /include/
  Processing folder (recursive): /usr/include/
cpptools/getFoldingRanges: file:///home/XXXXXX/Desktop/repro/main.cpp (id: 5)
cpptools/getDocumentSymbols: file:///home/XXXXXX/Desktop/repro/main.cpp (id: 6)
cpptools/abortRequest
cpptools/getDocumentSymbols
cpptools/getDocumentSymbols
cpptools/getFoldingRanges: file:///home/XXXXXX/Desktop/repro/main.cpp (id: 7)
cpptools/fileCreated: file:///home/XXXXXX/.config/Code%20-%20Insiders/logs/20200706T142658/sharedprocess.log
cpptools/fileCreated: file:///home/XXXXXX/.config/Code%20-%20Insiders/logs/20200706T142658/telemetry.log
cpptools/fileCreated: file:///home/XXXXXX/.config/Code%20-%20Insiders/logs/20200706T142658/userDataSync.log
Failed to read response from server: 22
(crash)

[sean-mcmanus]

A workaround appears to be to set C_Cpp.intelliSenseCacheSize to 0. Let me know if that doesn't work for you.

Simplified repro is

#include <algorithm>

int main()
{
    int v[3] = { 0, 1, 2 }; 
    std::rotate(std::begin(v), std::begin(v) + 1, std::end(v)); 
}

[olekolek1000]

Works perfectly without PCH/cache :)

[sean-mcmanus]

I mistakenly thought the bug didn't repro with VS, but Colen discovered that it did. I've filed bug https://developercommunity.visualstudio.com/content/problem/1109849/cc-intellisense-process-crashes-when-stdrotate-is.html .

[sean-mcmanus]

Should be fixed with https://github.com/microsoft/vscode-cpptools/releases/tag/0.30.0-insiders