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   1 @c -*-texinfo-*-
   2 @c This is part of the GNU Emacs Lisp Reference Manual.
   3 @c Copyright (C) 1990-1993, 1999, 2001-2016 Free Software Foundation,
   4 @c Inc.
   5 @c See the file elisp.texi for copying conditions.
   6 @node Standard Errors
   7 @appendix Standard Errors
   8 @cindex standard errors
   9
  10   Here is a list of the more important error symbols in standard Emacs, grouped
  11 by concept.  The list includes each symbol's message and a cross reference
  12 to a description of how the error can occur.
  13
  14   Each error symbol has an set of parent error conditions that is a
  15 list of symbols.  Normally this list includes the error symbol itself
  16 and the symbol @code{error}.  Occasionally it includes additional
  17 symbols, which are intermediate classifications, narrower than
  18 @code{error} but broader than a single error symbol.  For example, all
  19 the errors in accessing files have the condition @code{file-error}.  If
  20 we do not say here that a certain error symbol has additional error
  21 conditions, that means it has none.
  22
  23   As a special exception, the error symbol @code{quit} does not have the
  24 condition @code{error}, because quitting is not considered an error.
  25
  26   Most of these error symbols are defined in C (mainly @file{data.c}),
  27 but some are defined in Lisp.  For example, the file @file{userlock.el}
  28 defines the @code{file-locked} and @code{file-supersession} errors.
  29 Several of the specialized Lisp libraries distributed with Emacs
  30 define their own error symbols.  We do not attempt to list of all
  31 those here.
  32
  33   @xref{Errors}, for an explanation of how errors are generated and
  34 handled.
  35
  36 @table @code
  37 @item error
  38 The message is @samp{error}.  @xref{Errors}.
  39
  40 @item quit
  41 The message is @samp{Quit}.  @xref{Quitting}.
  42
  43 @item args-out-of-range
  44 The message is @samp{Args out of range}.  This happens when trying to
  45 access an element beyond the range of a sequence, buffer, or other
  46 container-like object.  @xref{Sequences Arrays Vectors}, and
  47 @xref{Text}.
  48
  49 @item arith-error
  50 The message is @samp{Arithmetic error}.  This occurs when trying to
  51 perform integer division by zero.  @xref{Numeric Conversions}, and
  52 @xref{Arithmetic Operations}.
  53
  54 @item beginning-of-buffer
  55 The message is @samp{Beginning of buffer}.  @xref{Character Motion}.
  56
  57 @item buffer-read-only
  58 The message is @samp{Buffer is read-only}.  @xref{Read Only Buffers}.
  59
  60 @item circular-list
  61 The message is @samp{List contains a loop}.  This happens when a
  62 circular structure is encountered.  @xref{Circular Objects}.
  63
  64 @item cl-assertion-failed
  65 The message is @samp{Assertion failed}.  This happens when the
  66 @code{cl-assert} macro fails a test.  @xref{Assertions,,, cl, Common Lisp
  67 Extensions}.
  68
  69 @item coding-system-error
  70 The message is @samp{Invalid coding system}.  @xref{Lisp and Coding
  71 Systems}.
  72
  73 @item cyclic-function-indirection
  74 The message is @samp{Symbol's chain of function indirections contains
  75 a loop}.  @xref{Function Indirection}.
  76
  77 @item cyclic-variable-indirection
  78 The message is @samp{Symbol's chain of variable indirections contains
  79 a loop}.  @xref{Variable Aliases}.
  80
  81 @item dbus-error
  82 The message is @samp{D-Bus error}.  This is only defined if Emacs was
  83 compiled with D-Bus support.  @xref{Errors and Events,,, dbus, D-Bus
  84 integration in Emacs}.
  85
  86 @item end-of-buffer
  87 The message is @samp{End of buffer}.  @xref{Character Motion}.
  88
  89 @item end-of-file
  90 The message is @samp{End of file during parsing}.  Note that this is
  91 not a subcategory of @code{file-error}, because it pertains to the
  92 Lisp reader, not to file I/O@.  @xref{Input Functions}.
  93
  94 @item file-already-exists
  95 This is a subcategory of @code{file-error}.  @xref{Writing to Files}.
  96
  97 @item file-date-error
  98 This is a subcategory of @code{file-error}.  It occurs when
  99 @code{copy-file} tries and fails to set the last-modification time of
 100 the output file.  @xref{Changing Files}.
 101
 102 @item file-error
 103 We do not list the error-strings of this error and its subcategories,
 104 because the error message is normally constructed from the data items
 105 alone when the error condition @code{file-error} is present.  Thus,
 106 the error-strings are not very relevant.  However, these error symbols
 107 do have @code{error-message} properties, and if no data is provided,
 108 the @code{error-message} property @emph{is} used.  @xref{Files}.
 109
 110 @c jka-compr.el
 111 @item compression-error
 112 This is a subcategory of @code{file-error}, which results from
 113 problems handling a compressed file.  @xref{How Programs Do Loading}.
 114
 115 @c userlock.el
 116 @item file-locked
 117 This is a subcategory of @code{file-error}.  @xref{File Locks}.
 118
 119 @c userlock.el
 120 @item file-supersession
 121 This is a subcategory of @code{file-error}.  @xref{Modification Time}.
 122
 123 @c filenotify.el
 124 @item file-notify-error
 125 This is a subcategory of @code{file-error}.  It happens, when a file
 126 could not be watched for changes.  @xref{File Notifications}.
 127
 128 @c net/ange-ftp.el
 129 @item ftp-error
 130 This is a subcategory of @code{file-error}, which results from
 131 problems in accessing a remote file using ftp.  @xref{Remote Files,,,
 132 emacs, The GNU Emacs Manual}.
 133
 134 @item invalid-function
 135 The message is @samp{Invalid function}.  @xref{Function Indirection}.
 136
 137 @item invalid-read-syntax
 138 The message is @samp{Invalid read syntax}.  @xref{Printed
 139 Representation}.
 140
 141 @item invalid-regexp
 142 The message is @samp{Invalid regexp}.  @xref{Regular Expressions}.
 143
 144 @c simple.el
 145 @item mark-inactive
 146 The message is @samp{The mark is not active now}.  @xref{The Mark}.
 147
 148 @item no-catch
 149 The message is @samp{No catch for tag}.  @xref{Catch and Throw}.
 150
 151 @ignore
 152 @c Not actually used for anything?  Probably definition should be removed.
 153 @item protected-field
 154 The message is @samp{Attempt to modify a protected file}.
 155 @end ignore
 156
 157 @item scan-error
 158 The message is @samp{Scan error}.  This happens when certain
 159 syntax-parsing functions find invalid syntax or mismatched
 160 parentheses.  Conventionally raised with three argument: a
 161 human-readable error message, the start of the obstacle that cannot be
 162 moved over, and the end of the obstacle.  @xref{List Motion}, and
 163 @xref{Parsing Expressions}.
 164
 165 @item search-failed
 166 The message is @samp{Search failed}.  @xref{Searching and Matching}.
 167
 168 @item setting-constant
 169 The message is @samp{Attempt to set a constant symbol}.  This happens
 170 when attempting to assign values to @code{nil}, @code{t}, and keyword
 171 symbols.  @xref{Constant Variables}.
 172
 173 @c simple.el
 174 @item text-read-only
 175 The message is @samp{Text is read-only}.  This is a subcategory of
 176 @code{buffer-read-only}.  @xref{Special Properties}.
 177
 178 @item undefined-color
 179 The message is @samp{Undefined color}.  @xref{Color Names}.
 180
 181 @item user-error
 182 The message is the empty string.  @xref{Signaling Errors}.
 183
 184 @item void-function
 185 The message is @samp{Symbol's function definition is void}.
 186 @xref{Function Cells}.
 187
 188 @item void-variable
 189 The message is @samp{Symbol's value as variable is void}.
 190 @xref{Accessing Variables}.
 191
 192 @item wrong-number-of-arguments
 193 The message is @samp{Wrong number of arguments}.  @xref{Classifying
 194 Lists}.
 195
 196 @item wrong-type-argument
 197 The message is @samp{Wrong type argument}.  @xref{Type Predicates}.
 198 @end table
 199
 200 @ignore    The following seem to be unused now.
 201   The following kinds of error, which are classified as special cases of
 202 @code{arith-error}, can occur on certain systems for invalid use of
 203 mathematical functions.  @xref{Math Functions}.
 204
 205 @table @code
 206 @item domain-error
 207 The message is @samp{Arithmetic domain error}.
 208
 209 @item overflow-error
 210 The message is @samp{Arithmetic overflow error}.  This is a subcategory
 211 of @code{domain-error}.
 212
 213 @item range-error
 214 The message is @code{Arithmetic range error}.
 215
 216 @item singularity-error
 217 The message is @samp{Arithmetic singularity error}.  This is a
 218 subcategory of @code{domain-error}.
 219
 220 @item underflow-error
 221 The message is @samp{Arithmetic underflow error}.  This is a
 222 subcategory of @code{domain-error}.
 223 @end table
 224 @end ignore