demangling

Demangling is the process of converting a mangled symbol name produced by a compiler into a human-readable form. Name mangling encodes information such as namespaces, classes, overloads, and function signatures into a single symbol in the object file. This enables languages with features like overloading or templates to generate unique linker symbols, but makes raw symbols difficult to read. Demangling is used in error messages, stack traces, debuggers, and profiling tools to present comprehensible identifiers.

Most C++ implementations use an ABI-specific mangling scheme, such as the Itanium C++ ABI. For example, the mangled symbol _ZN3foo3barEv corresponds to the function foo::bar(). Demangling is performed by language- or ABI-specific utilities that implement the same encoding rules the compiler uses. Common tools include c++filt (from GNU binutils) and the C++ ABI demangler abi::__cxa_demangle in libstdc++, or clang’s demangling facilities. Other languages have their own schemes and dedicated demanglers, such as rustfilt for Rust and various Swift demanglers, often available as part of debugging toolchains.

Limitations of demangling include its language- and ABI-specific nature; a demangled name is accurate only within the context of the same encoding rules. Demangled output usually conveys the high-level signature but may not restore full debugging information such as parameter names or template parameter details beyond what the symbol encodes. In stripped or heavily optimized binaries, information may be incomplete, but demangling remains a standard aid for interpreting linker symbols and runtime traces.