# Extra Clang Tools 22.1.2 documentation

## clang-tidy - misc-unused-using-decls

# misc-unused-using-decls

Finds unused `using` declarations.

Unused `using` declarations in header files will not be diagnosed since these using declarations are part of the header’s public API. Allowed header file extensions can be configured via the global option HeaderFileExtensions.

Example:

    // main.cpp
    namespace n { class C; }
    using n::C;  // Never actually used.