1C++FILT(1)                   GNU Development Tools                  C++FILT(1)
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NAME

6       c++filt - demangle C++ and Java symbols
7

SYNOPSIS

9       c++filt [-_|--strip-underscore]
10               [-n|--no-strip-underscore]
11               [-p|--no-params]
12               [-t|--types]
13               [-i|--no-verbose]
14               [-r|--no-recurse-limit]
15               [-R|--recurse-limit]
16               [-s format|--format=format]
17               [--help]  [--version]  [symbol...]
18

DESCRIPTION

20       The C++ and Java languages provide function overloading, which means
21       that you can write many functions with the same name, providing that
22       each function takes parameters of different types.  In order to be able
23       to distinguish these similarly named functions C++ and Java encode them
24       into a low-level assembler name which uniquely identifies each
25       different version.  This process is known as mangling. The c++filt [1]
26       program does the inverse mapping: it decodes (demangles) low-level
27       names into user-level names so that they can be read.
28
29       Every alphanumeric word (consisting of letters, digits, underscores,
30       dollars, or periods) seen in the input is a potential mangled name.  If
31       the name decodes into a C++ name, the C++ name replaces the low-level
32       name in the output, otherwise the original word is output.  In this way
33       you can pass an entire assembler source file, containing mangled names,
34       through c++filt and see the same source file containing demangled
35       names.
36
37       You can also use c++filt to decipher individual symbols by passing them
38       on the command line:
39
40               c++filt <symbol>
41
42       If no symbol arguments are given, c++filt reads symbol names from the
43       standard input instead.  All the results are printed on the standard
44       output.  The difference between reading names from the command line
45       versus reading names from the standard input is that command-line
46       arguments are expected to be just mangled names and no checking is
47       performed to separate them from surrounding text.  Thus for example:
48
49               c++filt -n _Z1fv
50
51       will work and demangle the name to "f()" whereas:
52
53               c++filt -n _Z1fv,
54
55       will not work.  (Note the extra comma at the end of the mangled name
56       which makes it invalid).  This command however will work:
57
58               echo _Z1fv, | c++filt -n
59
60       and will display "f(),", i.e., the demangled name followed by a
61       trailing comma.  This behaviour is because when the names are read from
62       the standard input it is expected that they might be part of an
63       assembler source file where there might be extra, extraneous characters
64       trailing after a mangled name.  For example:
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66                   .type   _Z1fv, @function
67

OPTIONS

69       -_
70       --strip-underscore
71           On some systems, both the C and C++ compilers put an underscore in
72           front of every name.  For example, the C name "foo" gets the low-
73           level name "_foo".  This option removes the initial underscore.
74           Whether c++filt removes the underscore by default is target
75           dependent.
76
77       -n
78       --no-strip-underscore
79           Do not remove the initial underscore.
80
81       -p
82       --no-params
83           When demangling the name of a function, do not display the types of
84           the function's parameters.
85
86       -t
87       --types
88           Attempt to demangle types as well as function names.  This is
89           disabled by default since mangled types are normally only used
90           internally in the compiler, and they can be confused with non-
91           mangled names.  For example, a function called "a" treated as a
92           mangled type name would be demangled to "signed char".
93
94       -i
95       --no-verbose
96           Do not include implementation details (if any) in the demangled
97           output.
98
99       -r
100       -R
101       --recurse-limit
102       --no-recurse-limit
103       --recursion-limit
104       --no-recursion-limit
105           Enables or disables a limit on the amount of recursion performed
106           whilst demangling strings.  Since the name mangling formats allow
107           for an infinite level of recursion it is possible to create strings
108           whose decoding will exhaust the amount of stack space available on
109           the host machine, triggering a memory fault.  The limit tries to
110           prevent this from happening by restricting recursion to 2048 levels
111           of nesting.
112
113           The default is for this limit to be enabled, but disabling it may
114           be necessary in order to demangle truly complicated names.  Note
115           however that if the recursion limit is disabled then stack
116           exhaustion is possible and any bug reports about such an event will
117           be rejected.
118
119           The -r option is a synonym for the --no-recurse-limit option.  The
120           -R option is a synonym for the --recurse-limit option.
121
122       -s format
123       --format=format
124           c++filt can decode various methods of mangling, used by different
125           compilers.  The argument to this option selects which method it
126           uses:
127
128           "auto"
129               Automatic selection based on executable (the default method)
130
131           "gnu"
132               the one used by the GNU C++ compiler (g++)
133
134           "lucid"
135               the one used by the Lucid compiler (lcc)
136
137           "arm"
138               the one specified by the C++ Annotated Reference Manual
139
140           "hp"
141               the one used by the HP compiler (aCC)
142
143           "edg"
144               the one used by the EDG compiler
145
146           "gnu-v3"
147               the one used by the GNU C++ compiler (g++) with the V3 ABI.
148
149           "java"
150               the one used by the GNU Java compiler (gcj)
151
152           "gnat"
153               the one used by the GNU Ada compiler (GNAT).
154
155       --help
156           Print a summary of the options to c++filt and exit.
157
158       --version
159           Print the version number of c++filt and exit.
160
161       @file
162           Read command-line options from file.  The options read are inserted
163           in place of the original @file option.  If file does not exist, or
164           cannot be read, then the option will be treated literally, and not
165           removed.
166
167           Options in file are separated by whitespace.  A whitespace
168           character may be included in an option by surrounding the entire
169           option in either single or double quotes.  Any character (including
170           a backslash) may be included by prefixing the character to be
171           included with a backslash.  The file may itself contain additional
172           @file options; any such options will be processed recursively.
173

FOOTNOTES

175       1.  MS-DOS does not allow "+" characters in file names, so on MS-DOS
176           this program is named CXXFILT.
177

SEE ALSO

179       the Info entries for binutils.
180
182       Copyright (c) 1991-2023 Free Software Foundation, Inc.
183
184       Permission is granted to copy, distribute and/or modify this document
185       under the terms of the GNU Free Documentation License, Version 1.3 or
186       any later version published by the Free Software Foundation; with no
187       Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
188       Texts.  A copy of the license is included in the section entitled "GNU
189       Free Documentation License".
190
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193binutils-2.41                     2023-08-16                        C++FILT(1)
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