How to use vscode-clangd with c++11?

Question

How to conf vscode-clangd to use c++11 for lint?

I added both complie_commands.json and complie_flags.txt in workshop.

workshop
|-complie_commands.json
|-complie_flags.txt
|-list.cpp

---

complie_commands.json

[
   { "directory": "pathto/workshop/",
     "command": "/opt/rh/llvm-toolset-7/root/usr/bin/clang++ -o file *cpp -std=c++11"}
]

compile_flags.txt

-std=c++11

---

It couldn't recognize auto with error:

'auto' type specifier is a C++11 extension

Answer 1

Set cppStandard in c_cpp_properties.json to c++11. e.g.:

{
  "env": {
    "myDefaultIncludePath": ["${workspaceFolder}", "${workspaceFolder}/include"],
    "myCompilerPath": "/usr/local/bin/gcc-7"
  },
  "configurations": [
    {
      "name": "Linux",
      "intelliSenseMode": "clang-x64",
      "includePath": ["${myDefaultIncludePath}", "/another/path"],
      "macFrameworkPath": ["/System/Library/Frameworks"],
      "defines": ["FOO", "BAR=100"],
      "forcedInclude": ["${workspaceFolder}/include/config.h"],
      "compilerPath": "/usr/bin/clang",
      "cStandard": "c11",
      "cppStandard": "c++11",
      "compileCommands": "/path/to/compile_commands.json",
      "browse": {
        "path": ["${workspaceFolder}"],
        "limitSymbolsToIncludedHeaders": true,
        "databaseFilename": ""
      }
    }
  ],
  "version": 4
}

Answer 2

Note: I've Q&A this kind of question with more details in here

Intro

clangd first check for a compilation database in the directory containing the source file, and then walk up into parent directories until we find one.

compilation database can be:

1. complie_commands.json: which usually generated by a build system like CMake:

# add the following line to your `CMakeLists.txt` script:
set(CMAKE_EXPORT_COMPILE_COMMANDS ON)

• Every "{...}" in .json file corresponds to a single file(tedious and error-prone to write by hand)
• See: Generating a JSON compilation database

2. compile_flags.txt: for simple projects like yours(for all files).

Solution:

As for you, just delete your complie_commands.json keep your compile_flags.txt.

If you really want to try, see format and example and try.

---

Not Recommended way

You can fix this by adding these config file. (if no compilation database is found)

1. cmd/ctrl + shift + p: Preferences: Open User Settings （JSON）
2. Add a single line into your settings.json file:

"clangd.fallbackFlags": [
    "-std=c++11",
    "-std=c99"  // in case you need to write C
  ],

3. cmd/ctrl + shift + p: clangd: Restart language server

Boom, it worked now!

It will cause .h file error... So not recommended for now.