Documenting AC_LANG_CASE

[Pavel Roskin]

ChangeLog:
        * doc/autoconf.texi (Fortran 77 Compiler Characteristics):
        Don't suggest obsolete AC_LANG_FORTRAN77.
        (Language Choice): Partly rewritten. Documented AC_LANG_CASE.

Regards,
Pavel Roskin

_____________________
Index: doc/autoconf.texi
--- doc/autoconf.texi   Fri Nov 17 12:27:15 2000
+++ doc/autoconf.texi   Thu Nov 23 17:04:06 2000
@@ -4409,7 +4409,7 @@
 check for characteristics not listed here, use @code{AC_TRY_COMPILE}
 (@pxref{Examining Syntax}) or @code{AC_TRY_RUN} (@pxref{Run Time}),
 making sure to first set the current language to Fortran 77
address@hidden (@pxref{Language Choice}).
address@hidden(Fortran 77)} (@pxref{Language Choice}).

 @defmac AC_F77_LIBRARY_LDFLAGS
 @maindex F77_LIBRARY_LDFLAGS
@@ -6038,10 +6038,12 @@
 @section Language Choice
 @cindex Language

-Packages that use both C and C++ need to test features of both
-compilers.  Autoconf-generated @code{configure} scripts check for C
-features by default.  The following macros determine which language's
-compiler is used in tests that follow in @file{configure.in}.
+Autoconf-generated @code{configure} scripts check for the C compiler and
+its features by default.  Packages that use other programming languages
+(maybe more than one, e.g. C and C++) need to test features of the
+compilers for the respective languages.  The following macros determine
+which programming language is used in the subsequent tests in
address@hidden

 @defmac AC_LANG (@var{language})
 Do compilation tests using the compiler, preprocessor and file
@@ -6075,6 +6077,15 @@
 @maindex LANG_POP
 Select the language that is saved on the top of the stack, as set by
 @code{AC_LANG_PUSH}, and remove it from the stack.
address@hidden defmac
+
+Following macros make it possible to write tests for many languages:
+
address@hidden AC_LANG_CASE (@var{language1}, @var{if-language1}, 
@ovar{language2}, @ovar{if-language2}, @dots{})
address@hidden LANG_CASE
+If @var{language1} is currently used, expand to @var{if-language1},
+otherwise if @var{language2} is currently used, expand to
address@hidden and so on.
 @end defmac

 @defmac AC_REQUIRE_CPP
_____________________