fix(clangd[lsp]): Args aren't being passed correctly.

[Jint-lzxy]

There've been updates to clangd (llvm, 13 - 14) that modified the method to pass args to the lsp.

TL;DR: We need to use the cmd table to pass clangd's arguments and set command-line arguments of the compiler (e.g., clang++) via clangd's configuration file in the source tree or an OS-specific directory. For most cases, --query-driver MUST be set so that clangd can correctly parse system's includes (e.g., for using #include<type_traits>), especially when the user doesn't provide compile_commands.json or compile_flags.txt.

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Detailed Discussion about Configuration File (Maybe we need to add this to the wiki?)

Configuration is stored in YAML files. These are either:

• project configuration: a file named .clangd in the source tree. (clangd searches in all parent directories of the active file).
  • Generally this should be used for shared and checked-in settings.
  • (Existing directories named .clangd can be deleted. These were used for temporary storage by clangd before version 11.)
• user configuration: a config.yaml file in an OS-specific directory:
  • Windows: %LocalAppData%\clangd\config.yaml, typically C:\Users\Bob\AppData\Local\clangd\config.yaml.
  • macOS: ~/Library/Preferences/clangd/config.yaml.
  • Linux and others: $XDG_CONFIG_HOME/clangd/config.yaml, typically ~/.config/clangd/config.yaml.

Example (My) Configuration

CompileFlags:
  Add: [-Wall, -Wextra, -pedantic, -std=c++17]
  Remove: # Nothing.
  Compiler: clang++
Diagnostics:
  ClangTidy:
    Add: ["*"]
    Remove:
      [
        altera-*,
        bugprone-easily-swappable-parameters,
        cppcoreguidelines-avoid-c-arrays,
        cppcoreguidelines-avoid-non-const-global-variables,
        cppcoreguidelines-owning-memory,
        cppcoreguidelines-pro-bounds-constant-array-index,
        cppcoreguidelines-pro-bounds-pointer-arithmetic,
        cppcoreguidelines-pro-bounds-array-to-pointer-decay,
        cppcoreguidelines-pro-type-reinterpret-cast,
        cppcoreguidelines-pro-type-vararg,
        fuchsia-default-arguments-calls,
        fuchsia-default-arguments-declarations,
        fuchsia-overloaded-operator,
        fuchsia-statically-constructed-objects,
        google-build-using-namespace,
        google-objc-function-naming,
        google-readability-braces-around-statements,
        google-readability-casting,
        hicpp-avoid-c-arrays,
        hicpp-braces-around-statements,
        hicpp-no-array-decay,
        hicpp-signed-bitwise,
        hicpp-vararg,
        llvm-else-after-return,
        llvmlibc-callee-namespace,
        llvmlibc-implementation-in-namespace,
        llvmlibc-restrict-system-libc-headers,
        misc-no-recursion,
        modernize-avoid-c-arrays,
        modernize-use-nodiscard,
        modernize-use-trailing-return-type,
        readability-braces-around-statements,
        readability-else-after-return,
        readability-magic-numbers,
        readability-redundant-access-specifiers,
      ]
    CheckOptions:
      readability-identifier-naming.VariableCase: [CamelCase]
InlayHints:
  Enabled: No
  ParameterNames: Yes
  DeducedTypes: Yes
Hover:
  ShowAKA: Yes
Index:
  Background: Build

For more details visit: nvim-lspconfig's server setup document and LLVM clangd's website.