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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | FOOTNOTES | SEE ALSO | COPYRIGHT | COLOPHON |
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C++FILT(1) GNU Development Tools C++FILT(1)
c++filt - demangle C++ and Java symbols
c++filt [-_|--strip-underscore]
[-n|--no-strip-underscore]
[-p|--no-params]
[-t|--types]
[-i|--no-verbose]
[-r|--no-recurse-limit]
[-R|--recurse-limit]
[-s format|--format=format]
[--help] [--version] [symbol...]
The C++ and Java languages provide function overloading, which
means that you can write many functions with the same name,
providing that each function takes parameters of different types.
In order to be able to distinguish these similarly named
functions C++ and Java encode them into a low-level assembler
name which uniquely identifies each different version. This
process is known as mangling. The c++filt [1] program does the
inverse mapping: it decodes (demangles) low-level names into
user-level names so that they can be read.
Every alphanumeric word (consisting of letters, digits,
underscores, dollars, or periods) seen in the input is a
potential mangled name. If the name decodes into a C++ name, the
C++ name replaces the low-level name in the output, otherwise the
original word is output. In this way you can pass an entire
assembler source file, containing mangled names, through c++filt
and see the same source file containing demangled names.
You can also use c++filt to decipher individual symbols by
passing them on the command line:
c++filt <symbol>
If no symbol arguments are given, c++filt reads symbol names from
the standard input instead. All the results are printed on the
standard output. The difference between reading names from the
command line versus reading names from the standard input is that
command-line arguments are expected to be just mangled names and
no checking is performed to separate them from surrounding text.
Thus for example:
c++filt -n _Z1fv
will work and demangle the name to "f()" whereas:
c++filt -n _Z1fv,
will not work. (Note the extra comma at the end of the mangled
name which makes it invalid). This command however will work:
echo _Z1fv, | c++filt -n
and will display "f(),", i.e., the demangled name followed by a
trailing comma. This behaviour is because when the names are
read from the standard input it is expected that they might be
part of an assembler source file where there might be extra,
extraneous characters trailing after a mangled name. For
example:
.type _Z1fv, @function
-_
--strip-underscore
On some systems, both the C and C++ compilers put an
underscore in front of every name. For example, the C name
"foo" gets the low-level name "_foo". This option removes
the initial underscore. Whether c++filt removes the
underscore by default is target dependent.
-n
--no-strip-underscore
Do not remove the initial underscore.
-p
--no-params
When demangling the name of a function, do not display the
types of the function's parameters.
-t
--types
Attempt to demangle types as well as function names. This is
disabled by default since mangled types are normally only
used internally in the compiler, and they can be confused
with non-mangled names. For example, a function called "a"
treated as a mangled type name would be demangled to "signed
char".
-i
--no-verbose
Do not include implementation details (if any) in the
demangled output.
-r
-R
--recurse-limit
--no-recurse-limit
--recursion-limit
--no-recursion-limit
Enables or disables a limit on the amount of recursion
performed whilst demangling strings. Since the name mangling
formats allow for an infinite level of recursion it is
possible to create strings whose decoding will exhaust the
amount of stack space available on the host machine,
triggering a memory fault. The limit tries to prevent this
from happening by restricting recursion to 2048 levels of
nesting.
The default is for this limit to be enabled, but disabling it
may be necessary in order to demangle truly complicated
names. Note however that if the recursion limit is disabled
then stack exhaustion is possible and any bug reports about
such an event will be rejected.
The -r option is a synonym for the --no-recurse-limit option.
The -R option is a synonym for the --recurse-limit option.
-s format
--format=format
c++filt can decode various methods of mangling, used by
different compilers. The argument to this option selects
which method it uses:
"auto"
Automatic selection based on executable (the default
method)
"gnu"
the one used by the GNU C++ compiler (g++)
"lucid"
the one used by the Lucid compiler (lcc)
"arm"
the one specified by the C++ Annotated Reference Manual
"hp"
the one used by the HP compiler (aCC)
"edg"
the one used by the EDG compiler
"gnu-v3"
the one used by the GNU C++ compiler (g++) with the V3
ABI.
"java"
the one used by the GNU Java compiler (gcj)
"gnat"
the one used by the GNU Ada compiler (GNAT).
--help
Print a summary of the options to c++filt and exit.
--version
Print the version number of c++filt and exit.
@file
Read command-line options from file. The options read are
inserted in place of the original @file option. If file does
not exist, or cannot be read, then the option will be treated
literally, and not removed.
Options in file are separated by whitespace. A whitespace
character may be included in an option by surrounding the
entire option in either single or double quotes. Any
character (including a backslash) may be included by
prefixing the character to be included with a backslash. The
file may itself contain additional @file options; any such
options will be processed recursively.
1. MS-DOS does not allow "+" characters in file names, so on MS-
DOS this program is named CXXFILT.
the Info entries for binutils.
Copyright (c) 1991-2024 Free Software Foundation, Inc.
Permission is granted to copy, distribute and/or modify this
document under the terms of the GNU Free Documentation License,
Version 1.3 or any later version published by the Free Software
Foundation; with no Invariant Sections, with no Front-Cover
Texts, and with no Back-Cover Texts. A copy of the license is
included in the section entitled "GNU Free Documentation
License".
This page is part of the binutils (a collection of tools for
working with executable binaries) project. Information about the
project can be found at ⟨http://www.gnu.org/software/binutils/⟩.
If you have a bug report for this manual page, see
⟨http://sourceware.org/bugzilla/enter_bug.cgi?product=binutils⟩.
This page was obtained from the tarball binutils-2.42.tar.gz
fetched from ⟨https://ftp.gnu.org/gnu/binutils/⟩ on 2024-06-14.
If you discover any rendering problems in this HTML version of
the page, or you believe there is a better or more up-to-date
source for the page, or you have corrections or improvements to
the information in this COLOPHON (which is not part of the
original manual page), send a mail to [email protected]
binutils-2.42 2024-06-14 C++FILT(1)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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