Improve indexing in the ELisp manual

* doc/lispref/control.texi (Control Structures, Sequencing)
(Conditionals, Iteration, Catch and Throw, Handling Errors)
(Cleanups):
* doc/lispref/eval.texi (Self-Evaluating Forms)
(Symbol Forms, Function Forms, Macro Forms, Special Forms)
(Quoting, Backquote): Add index entries that begin with
"forms".  (Bug#33440)

2 files changed, 16 insertions, 0 deletions

diff --git a/doc/lispref/control.texi b/doc/lispref/control.texi
index 8989b7de91b..4e5422aaa70 100644
--- a/doc/lispref/control.texi
+++ b/doc/lispref/control.texi
@@ -6,6 +6,7 @@
 @node Control Structures
 @chapter Control Structures
 @cindex special forms for control structures
+@cindex forms for control structures
 @cindex control structures
 
   A Lisp program consists of a set of @dfn{expressions}, or
@@ -48,6 +49,7 @@ structure constructs (@pxref{Macros}).
 @section Sequencing
 @cindex sequencing
 @cindex sequential execution
+@cindex forms for sequential execution
 
   Evaluating forms in the order they appear is the most common way
 control passes from one form to another.  In some contexts, such as in a
@@ -146,6 +148,7 @@ following @var{forms}, in textual order, returning the result of
 @node Conditionals
 @section Conditionals
 @cindex conditional evaluation
+@cindex forms, conditional
 
   Conditional control structures choose among alternatives.  Emacs Lisp
 has five conditional forms: @code{if}, which is much the same as in
@@ -1273,6 +1276,7 @@ up being equivalent to @code{dolist} (@pxref{Iteration}).
 @section Iteration
 @cindex iteration
 @cindex recursion
+@cindex forms, iteration
 
   Iteration means executing part of a program repetitively.  For
 example, you might want to repeat some computation once for each element
@@ -1496,6 +1500,7 @@ exited.
 
 @node Catch and Throw
 @subsection Explicit Nonlocal Exits: @code{catch} and @code{throw}
+@cindex forms for nonlocal exits
 
   Most control constructs affect only the flow of control within the
 construct itself.  The function @code{throw} is the exception to this
@@ -1867,6 +1872,7 @@ variables precisely as they were at the time of the error.
 @subsubsection Writing Code to Handle Errors
 @cindex error handler
 @cindex handling errors
+@cindex forms for handling errors
 
   The usual effect of signaling an error is to terminate the command
 that is running and return immediately to the Emacs editor command loop.
@@ -2235,6 +2241,7 @@ and their conditions.
 @node Cleanups
 @subsection Cleaning Up from Nonlocal Exits
 @cindex nonlocal exits, cleaning up
+@cindex forms for cleanup
 
   The @code{unwind-protect} construct is essential whenever you
 temporarily put a data structure in an inconsistent state; it permits
diff --git a/doc/lispref/eval.texi b/doc/lispref/eval.texi
index 373b12e79d5..416815e1900 100644
--- a/doc/lispref/eval.texi
+++ b/doc/lispref/eval.texi
@@ -127,6 +127,7 @@ with the other types, which are self-evaluating forms.
 @cindex vector evaluation
 @cindex literal evaluation
 @cindex self-evaluating form
+@cindex form, self-evaluating
 
   A @dfn{self-evaluating form} is any form that is not a list or
 symbol.  Self-evaluating forms evaluate to themselves: the result of
@@ -179,6 +180,8 @@ program.  Here is an example:
 @node Symbol Forms
 @subsection Symbol Forms
 @cindex symbol evaluation
+@cindex symbol forms
+@cindex forms, symbol
 
   When a symbol is evaluated, it is treated as a variable.  The result
 is the variable's value, if it has one.  If the symbol has no value as
@@ -215,6 +218,7 @@ its value ordinarily cannot be changed.  @xref{Constant Variables}.
 @node Classifying Lists
 @subsection Classification of List Forms
 @cindex list form evaluation
+@cindex forms, list
 
   A form that is a nonempty list is either a function call, a macro
 call, or a special form, according to its first element.  These three
@@ -349,6 +353,7 @@ Here is how you could define @code{indirect-function} in Lisp:
 @subsection Evaluation of Function Forms
 @cindex function form evaluation
 @cindex function call
+@cindex forms, function call
 
   If the first element of a list being evaluated is a Lisp function
 object, byte-code object or primitive function object, then that list is
@@ -372,6 +377,7 @@ body form becomes the value of the function call.
 @node Macro Forms
 @subsection Lisp Macro Evaluation
 @cindex macro call evaluation
+@cindex forms, macro call
 
   If the first element of a list being evaluated is a macro object, then
 the list is a @dfn{macro call}.  When a macro call is evaluated, the
@@ -418,6 +424,7 @@ expansion.
 @node Special Forms
 @subsection Special Forms
 @cindex special forms
+@cindex forms, special
 @cindex evaluation of special forms
 
   A @dfn{special form} is a primitive function specially marked so that
@@ -539,6 +546,7 @@ described in @ref{Autoload}.
 
 @node Quoting
 @section Quoting
+@cindex forms, quote
 
   The special form @code{quote} returns its single argument, as written,
 without evaluating it.  This provides a way to include constant symbols
@@ -598,6 +606,7 @@ only part of a list, while computing and substituting other parts.
 @cindex backquote (list substitution)
 @cindex ` (list substitution)
 @findex `
+@cindex forms, backquote
 
   @dfn{Backquote constructs} allow you to quote a list, but
 selectively evaluate elements of that list.  In the simplest case, it