LLVM-CXXFILT(1)

💅 llvm-cxxfilt — bestie's guide to un-mangling names

okay so. this is a page from the LLVM manual collection, section 1, and it's about a lil tool called llvm-cxxfilt. the symbol name demangler. yes queen, we're decoding the cursed glyph soup today. ✨

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🎀 NAME 🎀

llvm-cxxfilt — the LLVM symbol name demangler. it takes names that look like a cat walked across the keyboard and turns them back into human words. iykyk 💖

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🌸 SYNOPSIS 🌸

llvm-cxxfilt [options] [mangled names...]

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🦋 DESCRIPTION 🦋

so llvm-cxxfilt is a symbol demangler, and the whole point is that you can use it as a drop-in replacement for the GNU c++filt tool. it takes a series of symbol names and prints their demangled form on the standard output stream. that's it, that's the job. 💅

and if a name can't be demangled? it just prints it as-is. no drama, no error, no nothing. it simply vibes. 🫶

if you don't specify any names on the command-line, then names get read interactively from the standard input stream instead. and here's the tea when you're reading from stdin: every input line gets split on characters that are not part of valid Itanium name manglings — meaning characters that are not alphanumeric, not '.', not '$', and not '_'. and the separators between names? those get copied to the output exactly as-is. lowkey elegant. ✨

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🍓 EXAMPLE 🍓

like, look at her go:

$ llvm-cxxfilt _Z3foov _Z3bari not_mangled
foo()
bar(int)
not_mangled
$ cat input.txt
| _Z3foov *** _Z3bari *** not_mangled |
$ llvm-cxxfilt < input.txt
| foo() *** bar(int) *** not_mangled |

see how not_mangled just walked through untouched? and the *** separators stayed put? that's the vibe check passing. ✅

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✨ OPTIONS ✨

here's every single flag, no skips, no skimming, we do not gatekeep here:

• --format=<value>, -s — the mangling scheme to assume. valid values are auto (which is the default, and it auto-detects the style) and gnu (which assumes GNU/Itanium style). pick your fighter. 🥊
• --help, -h — prints a summary of the command line options. bestie behavior fr fr.
• --no-params, -p — do not demangle function parameters or return types. just the name, none of the extra. 💀
• --no-strip-underscore, -n — do not strip a leading underscore. and heads up: this is the default for all platforms except Mach-O based hosts. so it's the opposite of the next one.
• --quote — adds " " around demangled names. and it does not quote names that are already quoted, because that would be chaotic. 🙈
• --strip-underscore, -_ — strips a single leading underscore, if there is one, from each input name before demangling. and this one is on by default on Mach-O based platforms. ✂️
• --types, -t — attempts to demangle names as type names as well as symbol names. ambitious. we love her.
• --version — displays the version of the llvm-cxxfilt executable. the "who even am i" option. 👑
• @<FILE> — reads command-line options from response file <FILE>. yes, a file full of flags. iconic.

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🌈 EXIT STATUS 🌈

llvm-cxxfilt returns 0 unless it hits a usage error — and in that case, a non-zero exit code gets returned. so if the number is big, something went sideways. 👀

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🔥 SEE ALSO 🔥

• llvm-nm(1) — go read that one too, bestie. 💜

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👑 AUTHOR 👑

maintained by the LLVM Team (https://llvm.org/). they're the ones keeping this whole thing alive. 🫡

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🧚 COPYRIGHT 🧚

2003-2025, LLVM Project — yes, that's two decades plus of demangling. periodt.

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okay so that's the whole page!! this came out of the LLVM project, and this particular page is dated 2025-09-03. mwah, go demangle something cursed, bestie 💖✨🌸