etags honours #line directives.

etc/NEWS

@@ -214,7 +214,7 @@ C-h c, C-h k, C-h w, and C-h f now handle remapped interactive commands.
   that command.
 
 For example, if C-k is bound to kill-line, and kill-line is remapped
-to new-kill-line, these commands now report: 
+to new-kill-line, these commands now report:
 
 - C-h c and C-h k C-k reports:
   C-k runs the command new-kill-line
@@ -366,6 +366,11 @@ additionally by looking for package::sub.
 *** New language PHP: tags are functions, classes and defines.  If
 the --members option is specified to etags, tags are vars also.
 
+*** Honour #line directives.  This is useful when dealing with C code
+created from Yacc sources, or with any file created from Cweb source
+files.  When etags tags the generated file, it writes tags pointing to
+the source file.
+
 +++
 ** The command line option --no-windows has been changed to
 --no-window-system.  The old one still works, but is deprecated.

etc/etags.1

@@ -59,7 +59,9 @@ table (defaults: \fBTAGS\fP for \fBetags\fP, \fBtags\fP for
 Files specified with relative file names will be recorded in the tag
 table with file names relative to the directory where the tag table
 resides.  Files specified with absolute file names will be recorded
-with absolute file names.
+with absolute file names.  Files generated from a source file\-\-like a C
+file created by a source Yacc file\-\-will be recorded with the name of the
+source file.
 The programs recognize the language used in an input file based on its
 file name and contents.  The \fB\-\-language\fP switch can be used to force
 parsing of the file names following the switch according to the given

man/maintaining.texi

@@ -179,8 +179,11 @@ definition of a function by looking up which of the files it is in.
 conventional name for a tags table file is @file{TAGS}.
 
   Each entry in the tags table records the name of one tag, the name of the
-file that the tag is defined in (implicitly), and the position in that file
-of the tag's definition.
+file that the tag is defined in (implicitly), and the position in that
+file of the tag's definition.  When a file parsed by @code{etags} is
+created from a different source file, like a C file created by
+@code{bison} from a source Yacc file, the tags of the parsed file
+reference the source file.
 
   Just what names from the described files are recorded in the tags table
 depends on the programming language of the described file.  They