improve doc index

With recent doc improvements, the index grew to be just large enough to tickle 
a current texinfo limitation, rather than cleanly splitting over two pages in a 
pdf or dvi manual:

http://www.nabble.com/overfull-%5Cvbox-in-%40printindex-tf3328666.html#a9255712

The solution was to add even more index entries (a rather useful task in and of 
itself), so that the index no longer runs off the bottom of a printed page.

2007-03-01  Eric Blake  <[email protected]>

	Avoid overfull \vbox warning from texinfo, due to indices that
	weren't quite big enough to split across page boundaries.
	* doc/m4.texinfo: Add lots of concept index entries.
	(Concept Index): Move to be last, as recommended by texinfo
	manual.
	(Define, Arguments, Pseudo Arguments): Add more function entries.


Index: doc/m4.texinfo
===================================================================
RCS file: /sources/m4/m4/doc/m4.texinfo,v
retrieving revision 1.1.1.1.2.118
diff -u -r1.1.1.1.2.118 m4.texinfo
--- doc/m4.texinfo	28 Feb 2007 21:51:36 -0000	1.1.1.1.2.118
+++ doc/m4.texinfo	1 Mar 2007 21:37:57 -0000
@@ -275,8 +275,8 @@
 
 Indices of concepts and macros
 
-* Concept index::               Index for many concepts
 * Macro index::                 Index for all @code{m4} macros
+* Concept index::               Index for many concepts
 
 @end detailmenu
 @end menu
@@ -302,6 +302,7 @@
 @node Intro
 @section Introduction to @code{m4}
 
+@cindex overview of @code{m4}
 @code{m4} is a macro processor, in the sense that it copies its
 input to the output, expanding macros as it goes.  Macros are either
 builtin or user-defined, and can take any number of arguments.
@@ -333,6 +334,8 @@
 @node History
 @section Historical references
 
+@cindex history of @code{m4}
+@cindex @acronym{GNU} M4, history of
 @code{GPM} was an important ancestor of @code{m4}.  See
 C. Stratchey: ``A General Purpose Macro generator'', Computer Journal
 8,3 (1965), pp. 225 ff.  @code{GPM} is also succinctly described into
@@ -391,6 +394,9 @@
 @node Bugs
 @section Problems and bugs
 
+@cindex reporting bugs
+@cindex bug reports
+@cindex suggestions, reporting
 If you have problems with @acronym{GNU} M4 or think you've found a bug,
 please report it.  Before reporting a bug, make sure you've actually
 found a real bug.  Carefully reread the documentation and see if it
@@ -417,6 +423,7 @@
 @node Manual
 @section Using this manual
 
+@cindex examples, understanding
 This manual contains a number of examples of @code{m4} input and output,
 and a simple notation is used to distinguish input, output and error
 messages from @code{m4}.  Examples are set out from the normal text, and
@@ -486,6 +493,8 @@
 @node Invoking m4
 @chapter Invoking @code{m4}
 
+@cindex command line
+@cindex invoking @code{m4}
 The format of the @code{m4} command is:
 
 @comment ignore
@@ -552,6 +561,8 @@
 
 @item -E
 @itemx --fatal-warnings
+@cindex errors, fatal
+@cindex fatal errors
 Controls the effect of warnings.  If unspecified, then execution
 continues and exit status is unaffected when a warning is printed.  If
 specified exactly once, warnings become fatal; when one is issued,
@@ -610,6 +621,7 @@
 
 @cindex macro definitions, on the command line
 @cindex command line, macro definitions on the
+@cindex preprocessor features
 Several options allow @code{m4} to behave more like a preprocessor.
 Macro definitions and deletions can be made on the command line, the
 search path can be altered, and the output file can track where the
@@ -633,6 +645,9 @@
 
 @item -s
 @itemx --synclines
+@cindex syncronization lines
+@cindex location, input
+@cindex input location
 Generate synchronization lines, for use by the C preprocessor or other
 similar tools.  Order is significant with respect to file names.  This
 option is useful, for example, when @code{m4} is used as a
@@ -682,6 +697,8 @@
 
 @item -L @var{NUM}
 @itemx --nesting-limit=@var{NUM}
+@cindex nesting limit
+@cindex limit, nesting
 Artificially limit the nesting of macro calls to @var{NUM} levels,
 stopping program execution if this limit is ever exceeded.  When not
 specified, nesting is limited to 1024 levels.  A value of zero means
@@ -694,6 +711,7 @@
 Most users would never need this option.  If shown to be obtrusive,
 this option (which is still experimental) might well disappear.
 
+@cindex rescanning
 This option does @emph{not} have the ability to break endless
 rescanning loops, since these do not necessarily consume much memory
 or stack space.  Through clever usage of rescanning loops, one can
@@ -844,6 +862,7 @@
 @section Macro names
 
 @cindex names
+@cindex words
 A name is any sequence of letters, digits, and the character @samp{_}
 (underscore), where the first character is not a digit.  @code{m4} will
 use the longest such sequence found in the input.  If a name has a
@@ -856,6 +875,7 @@
 @section Quoting input to @code{m4}
 
 @cindex quoted string
+@cindex string, quoted
 A quoted string is a sequence of characters surrounded by quote
 strings, defaulting to
 @samp{`} and @samp{'}, where the nested begin and end quotes within the
@@ -907,6 +927,7 @@
 @node Other tokens
 @section Other kinds of input tokens
 
+@cindex tokens, special
 Any character, that is neither a part of a name, nor of a quoted string,
 nor a comment, is a token by itself.  When not in the context of macro
 expansion, all of these tokens are just copied to output.  However,
@@ -1114,6 +1135,7 @@
 @section Macro invocation
 
 @cindex macro invocation
+@cindex invoking macros
 Macro invocations has one of the forms
 
 @comment ignore
@@ -1235,6 +1257,7 @@
 the @code{divert} builtin macro will be called, which expands to the
 empty string.
 
+@cindex rescanning
 The output of macro evaluations is always rescanned.  The following
 example would yield the string @samp{de}, exactly as if @code{m4}
 has been given @w{@samp{substr(`abcde', `3', `2')}} as input:
@@ -1316,6 +1339,8 @@
 @result{}
 @end example
 
+@cindex warnings, suppressing
+@cindex suppressing warnings
 Normally @code{m4} will issue warnings if a builtin macro is called
 with an inappropriate number of arguments, but it can be suppressed with
 the @option{--quiet} command line option (or @option{--silent}, or
@@ -1392,6 +1417,8 @@
 foo(`() (() (')
 @end example
 
+@cindex quoting rule of thumb
+@cindex rule of thumb, quoting
 It is, however, in certain cases necessary (because nested expansion
 must occur to create the arguments for the outer macro) or convenient
 (because it uses fewer characters) to leave out quotes for some
@@ -1526,7 +1553,15 @@
 (@pxref{Indir}) and @code{defn} (@pxref{Defn}).
 
 @cindex arrays
-Arrays and associative arrays can be simulated by using this trick.
+Arrays and associative arrays can be simulated by using non-standard
+macro names.
+
+@deffn Composite array (@var{index})
+@deffnx Composite array_set (@var{index}, @ovar{value})
+Provide access to entries within an array.  @code{array} reads the entry
+at location @var{index}, and @code{array_set} assigns @var{value} to
+location @var{index}.
+@end deffn
 
 @example
 define(`array', `defn(format(``array[%d]'', `$1'))')
@@ -1549,13 +1584,18 @@
 @section Arguments to macros
 
 @cindex macros, arguments to
-@cindex Arguments to macros
+@cindex arguments to macros
 Macros can have arguments.  The @var{n}th argument is denoted by
 @code{$n} in the expansion text, and is replaced by the @var{n}th actual
 argument, when the macro is expanded.  Replacement of arguments happens
 before rescanning, regardless of how many nesting levels of quoting
 appear in the expansion.  Here is an example of a macro with
-two arguments.  It simply exchanges the order of the two arguments.
+two arguments.
+
+@deffn Composite exch (@var{arg1}, @var{arg2})
+Expands to @var{arg2} followed by @var{arg1}, effectively exchanging
+their order.
+@end deffn
 
 @example
 define(`exch', `$2, $1')
@@ -1670,8 +1710,11 @@
 and for all the actual arguments.
 
 The number of actual arguments in a macro call is denoted by @code{$#}
-in the expansion text.  Thus, a macro to display the number of arguments
-given can be
+in the expansion text.
+
+@deffn Composite nargs (@dots{})
+Expands to a count of the number of arguments supplied.
+@end deffn
 
 @example
 define(`nargs', `$#')
@@ -1779,6 +1822,9 @@
 @result{}$$$ hello $$$
 @end example
 
+@cindex rescanning
+@cindex literal output
+@cindex output, literal
 If you want a macro to expand to something like @samp{$12}, the
 judicious use of nested quoting can put a safe character between the
 @code{$} and the next character, relying on the rescanning to remove the
@@ -1861,6 +1907,8 @@
 
 @cindex macros, how to rename
 @cindex renaming macros
+@cindex macros, displaying definitions
+@cindex definitions, displaying macro
 It is possible to rename an already defined macro.  To do this, you need
 the builtin @code{defn}:
 
@@ -1921,6 +1969,7 @@
 @result{}
 @end example
 
+@cindex rescanning
 However, it is important to remember that @code{m4} rescanning is purely
 textual.  If an unbalanced end-quote string occurs in a macro
 definition, the rescan will see that embedded quote as the termination
@@ -1943,6 +1992,8 @@
 @result{}AA'
 @end example
 
+@cindex builtins, special tokens
+@cindex tokens, builtin macro
 Using @code{defn} to generate special tokens for builtin macros outside
 of expected contexts can sometimes trigger warnings.  But most of the
 time, such tokens are silently converted to the empty string.
@@ -1963,6 +2014,8 @@
 @cindex macros, temporary redefinition of
 @cindex temporary redefinition of macros
 @cindex redefinition of macros, temporary
+@cindex definition stack
+@cindex stack, macro definition
 It is possible to redefine a macro temporarily, reverting to the
 previous definition at a later time.  This is done with the builtins
 @code{pushdef} and @code{popdef}:
@@ -2245,6 +2298,8 @@
 @section If-else construct, or multibranch
 
 @cindex comparing strings
+@cindex discarding input
+@cindex input, discarding
 The other conditional, @code{ifelse}, is much more powerful.  It can be
 used as a way to introduce a long comment, as an if-else construct, or
 as a multibranch, depending on the number of arguments supplied:
@@ -2317,6 +2372,8 @@
 @end example
 
 @cindex multibranches
+@cindex switch statement
+@cindex case statement
 However, @code{ifelse} can take more than four arguments.  If given more
 than four arguments, @code{ifelse} works like a @code{case} or @code{switch}
 statement in traditional programming languages.  If @var{string-1} and
@@ -2710,6 +2767,8 @@
 @node Debugging
 @chapter How to debug macros and input
 
+@cindex debugging macros
+@cindex macros, debugging
 When writing macros for @code{m4}, they often do not work as intended on
 the first try (as is the case with most programming languages).
 Fortunately, there is support for macro debugging in @code{m4}.
@@ -3044,6 +3103,8 @@
 @section Deleting whitespace in input
 
 @cindex deleting whitespace in input
+@cindex discarding input
+@cindex input, discarding
 The builtin @code{dnl} stands for ``Discard to Next Line'':
 
 @deffn Builtin dnl
@@ -3100,8 +3161,9 @@
 @node Changequote
 @section Changing the quote characters
 
-@cindex changing the quote delimiters
-@cindex quote delimiters, changing the
+@cindex changing quote delimiters
+@cindex quote delimiters, changing
+@cindex delimiters, changing
 The default quote delimiters can be changed with the builtin
 @code{changequote}:
 
@@ -3303,6 +3365,7 @@
 
 @cindex changing comment delimiters
 @cindex comment delimiters, changing
+@cindex delimiters, changing
 The default comment delimiters can be changed with the builtin
 macro @code{changecom}:
 
@@ -3447,6 +3510,9 @@
 
 @cindex lexical structure of words
 @cindex words, lexical structure of
+@cindex syntax, changing
+@cindex changing syntax
+@cindex regular expressions
 @quotation
 The macro @code{changeword} and all associated functionality is
 experimental.  It is only available if the @option{--enable-changeword}
@@ -3667,6 +3733,8 @@
 
 @cindex saving input
 @cindex input, saving
+@cindex deferring expansion
+@cindex expansion, deferring
 It is possible to `save' some text until the end of the normal input has
 been seen.  Text can be saved, to be read again by @code{m4} when the
 normal input has been exhausted.  This feature is normally used to
@@ -3877,6 +3945,7 @@
 @node Diversions
 @chapter Diverting and undiverting output
 
+@cindex deferring output
 Diversions are a way of temporarily saving output.  The output of
 @code{m4} can at any time be diverted to a temporary file, and be
 reinserted into the output stream, @dfn{undiverted}, again at a later
@@ -4024,6 +4093,8 @@
 @result{}Wrapped TEXT precedes diverted text.
 @end example
 
+@cindex discarding input
+@cindex input, discarding
 If output is diverted to a negative diversion, it is simply discarded.
 This can be used to suppress unwanted output.  A common example of
 unwanted output is the trailing newlines after macro definitions.  Here
@@ -4082,6 +4153,8 @@
 order given.  If no arguments are supplied, all diversions are
 undiverted, in numerical order.
 
+@cindex file inclusion
+@cindex inclusion, of files
 As a @acronym{GNU} extension, @var{diversions} may contain non-numeric
 strings, which are treated as the names of files to copy into the output
 without expansion.  A warning is issued if a file could not be opened.
@@ -4287,6 +4360,7 @@
 @node Index macro
 @section Searching for substrings
 
+@cindex substrings, locating
 Searching for substrings is done with @code{index}:
 
 @deffn Builtin index (@var{string}, @var{substring})
@@ -4316,14 +4390,17 @@
 @node Regexp
 @section Searching for regular expressions
 
+@cindex basic regular expressions
 @cindex regular expressions
+@cindex expressions, regular
 @cindex @acronym{GNU} extensions
 Searching for regular expressions is done with the builtin
 @code{regexp}:
 
 @deffn Builtin regexp (@var{string}, @var{regexp}, @ovar{replacement})
 Searches for @var{regexp} in @var{string}.  The syntax for regular
-expressions is the same as in @acronym{GNU} Emacs.
+expressions is the same as in @acronym{GNU} Emacs, which is similar to
+Basic Regular Expressions (@sc{BRE}) in @acronym{POSIX}.
 @ifnothtml
 @xref{Regexps, , Syntax of Regular Expressions, emacs, The GNU Emacs
 Manual}.
@@ -4333,6 +4410,8 @@
 @uref{http://www.gnu.org/@/software/@/emacs/@/manual/@/emacs.html#Regexps,
 Syntax of Regular Expressions} in the @acronym{GNU} Emacs Manual.
 @end ifhtml
+Support for Extended Regular Expressions (@sc{ERE}) is not available,
+but will be added in @acronym{GNU} M4 2.0.
 
 If @var{replacement} is omitted, @code{regexp} expands to the index of
 the first match of @var{regexp} in @var{string}.  If @var{regexp} does
@@ -4502,7 +4581,9 @@
 @node Patsubst
 @section Substituting text by regular expression
 
+@cindex basic regular expressions
 @cindex regular expressions
+@cindex expressions, regular
 @cindex pattern substitution
 @cindex substitution by regular expression
 @cindex @acronym{GNU} extensions
@@ -4973,10 +5054,7 @@
 @node Shell commands
 @chapter Macros for running shell commands
 
-@cindex executing UNIX commands
-@cindex running UNIX commands
 @cindex UNIX commands, running
-@cindex commands, running UNIX
 @cindex executing shell commands
 @cindex running shell commands
 @cindex shell commands, running
@@ -5032,7 +5110,6 @@
 @result{}Extensions are active
 @end example
 
-@cindex platform macro
 On UNIX systems, @acronym{GNU} @code{m4} will define @code{@w{__unix__}}
 by default, or @code{unix} when the @option{-G} option is specified.
 
@@ -5371,6 +5448,8 @@
 @node Location
 @section Printing current location
 
+@cindex location, input
+@cindex input location
 To make it possible to specify the location of an error, three
 utility builtins exist:
 
@@ -5785,7 +5864,7 @@
 is modeled after the C library function @code{printf} (@pxref{Format}).
 
 @item
-Searches and text substitution through regular expressions are
+Searches and text substitution through basic regular expressions are
 supported by the @code{regexp} (@pxref{Regexp}) and @code{patsubst}
 (@pxref{Patsubst}) builtins.
 
@@ -6035,7 +6114,6 @@
 @acronym{GNU} @code{m4} makes no attempt at prohibiting self-referential
 definitions like:
 
-@comment ignore
 @example
 define(`x', `x')
 @result{}
@@ -6043,8 +6121,10 @@
 @result{}
 @end example
 
+@cindex rescanning
 There is nothing inherently wrong with defining @samp{x} to
-return @samp{x}.  The wrong thing is to expand @samp{x} unquoted.
+return @samp{x}.  The wrong thing is to expand @samp{x} unquoted,
+because that would cause an infinite rescan loop.
 In @code{m4}, one might use macros to hold strings, as we do for
 variables in other programming languages, further checking them with:
 
@@ -6054,11 +6134,11 @@
 @end example
 
 @noindent
-In cases like this one, an interdiction for a macro to hold its own
-name would be a useless limitation.  Of course, this leaves more rope
-for the @acronym{GNU} @code{m4} user to hang himself!  Rescanning hangs may be
-avoided through careful programming, a little like for endless loops
-in traditional programming languages.
+In cases like this one, an interdiction for a macro to hold its own name
+would be a useless limitation.  Of course, this leaves more rope for the
+@acronym{GNU} @code{m4} user to hang himself!  Rescanning hangs may be
+avoided through careful programming, a little like for endless loops in
+traditional programming languages.
 @end itemize
 
 @node Answers
@@ -6173,6 +6253,8 @@
 @error{}m4trace: -3- shift(`4')
 @end example
 
+@cindex quadratic behavior, avoiding
+@cindex avoiding quadratic behavior
 Each successive iteration was adding more quoted @code{shift}
 invocations, and the entire list contents were passing through every
 iteration.  In general, when recursing, it is a good idea to make the
@@ -6413,27 +6495,24 @@
 @appendix Indices of concepts and macros
 
 @menu
-* Concept index::               Index for many concepts
 * Macro index::                 Index for all @code{m4} macros
+* Concept index::               Index for many concepts
 @end menu
 
-@node Concept index
-@appendixsec Index for many concepts
-
-@printindex cp
-
 @node Macro index
 @appendixsec Index for all @code{m4} macros
 
-References are exclusively to the places where a builtin is introduced
-the first time.
-
-@iftex
-@sp 1
-@end iftex
+This index covers all @code{m4} builtins, as well as several useful
+composite macros.  References are exclusively to the places where a
+macro is introduced the first time.
 
 @printindex fn
 
+@node Concept index
+@appendixsec Index for many concepts
+
+@printindex cp
+
 @bye
 
 @c Local Variables: