yacc: update NEWS and docs about yacc-generated headers extensions

* doc/automake.texi (Yacc and Lex): Document explicitly that
extensions of yacc-generated headers are modelled after the
extension of the corresponding sources.
* NEWS: Update.

1 files changed, 10 insertions, 6 deletions

diff --git a/doc/automake.texi b/doc/automake.texi
index dfd0019f1..701a88801 100644
--- a/doc/automake.texi
+++ b/doc/automake.texi
@@ -6048,12 +6048,16 @@ cause the intermediate file to be named @file{foo.c} (as opposed to
 @file{y.tab.c}, which is more traditional).
 
 The extension of a yacc source file is used to determine the extension
-of the resulting C or C++ file.  Files with the extension @file{.y}
-will be turned into @file{.c} files; likewise, @file{.yy} will become
-@file{.cc}; @file{.y++}, @file{c++}; @file{.yxx}, @file{.cxx}; and
-@file{.ypp}, @file{.cpp}.
-
-Likewise, lex source files can be used to generate C or C++; the
+of the resulting C or C++ source and header files.  Note that header
+files are generated only when the @option{-d} Yacc option is used; see
+below for more information about this flag, and how to specify it.
+Files with the extension @file{.y} will thus be turned into @file{.c}
+sources and @file{.h} headers; likewise, @file{.yy} will become
+@file{.cc} and @file{.hh}, @file{.y++} will become @file{c++} and
+@file{h++}, @file{.yxx} will become @file{.cxx} and @file{.hxx},
+and @file{.ypp} will become @file{.cpp} and @file{.hpp}.
+
+Similarly, lex source files can be used to generate C or C++; the
 extensions @file{.l}, @file{.ll}, @file{.l++}, @file{.lxx}, and
 @file{.lpp} are recognized.