Ignore comments at the beginning of the declarations section.

doc/gperf.texi

@@ -122,6 +122,7 @@ Input Format to @code{gperf}
 * Declarations::                Declarations.
 * Keywords::                    Format for Keyword Entries.
 * Functions::                   Including Additional C Functions.
+* Controls for GNU indent::     Where to place directives for GNU @code{indent}.
 
 Declarations
 
@@ -330,6 +331,7 @@ input format for each section.
 * Declarations::                Declarations.
 * Keywords::                    Format for Keyword Entries.
 * Functions::                   Including Additional C Functions.
+* Controls for GNU indent::     Where to place directives for GNU @code{indent}.
 @end menu
 
 It is possible to omit the declaration section entirely, if the @samp{-t}
@@ -685,7 +687,7 @@ declaration section.  If the @samp{-t} option (or, equivalently, the
 these fields are simply ignored.  All previous examples except the last
 one contain keyword attributes.
 
-@node Functions,  , Keywords, Input Format
+@node Functions, Controls for GNU indent, Keywords, Input Format
 @subsection Including Additional C Functions
 
 The optional third section also corresponds closely with conventions
@@ -695,6 +697,52 @@ file, is included verbatim into the generated output file.  Naturally,
 it is your responsibility to ensure that the code contained in this
 section is valid C.
 
+@node Controls for GNU indent,  , Functions, Input Format
+@subsection Where to place directives for GNU @code{indent}.
+
+If you want to invoke GNU @code{indent} on a @code{gperf} input file,
+you will see that GNU @code{indent} doesn't understand the @samp{%%},
+@samp{%@{} and @samp{%@}} directives that control @code{gperf}'s
+interpretation of the input file.  Therefore you have to insert some
+directives for GNU @code{indent}.  More precisely, assuming the most
+general input file structure
+
+@example
+@group
+declarations part 1
+%@{
+verbatim code
+%@}
+declarations part 2
+%%
+keywords
+%%
+functions
+@end group
+@end example
+
+@noindent
+you would insert @samp{*INDENT-OFF*} and @samp{*INDENT-ON*} comments
+as follows:
+
+@example
+@group
+/* *INDENT-OFF* */
+declarations part 1
+%@{
+/* *INDENT-ON* */
+verbatim code
+/* *INDENT-OFF* */
+%@}
+declarations part 2
+%%
+keywords
+%%
+/* *INDENT-ON* */
+functions
+@end group
+@end example
+
 @node Output Format, Binary Strings, Input Format, Description
 @section Output Format for Generated C Code with @code{gperf}
 @cindex hash table