minor Autoconf manual cleanups

[Paul Eggert]

I installed this:

2006-02-14  Paul Eggert  <address@hidden>

        * doc/autoconf.texi: Minor style cleanup.
        Be consistent about spaces after commas.
        Insert [] where empty args look a bit funny.
        Fix some "i.e." and "e.g." usages.
        Try to avoid "X/Y" usages.
        Don't be pedantic about "ISO C99"; just say C99.
        Prefer GNU style for spaces in front of parens.
        (Function Portability): Comment about C89 versus C99
        signed integer division.
        (Particular Headers): Use current gnulib style for dirent
        includes.

--- doc/autoconf.texi   14 Feb 2006 23:18:51 -0000      1.947
+++ doc/autoconf.texi   15 Feb 2006 06:42:16 -0000      1.948
@@ -799,7 +799,7 @@ The home pages for
 
 @item Automake Manual
 
address@hidden,,Automake,automake,@acronym{GNU} Automake}, for more
address@hidden, , Automake, automake, @acronym{GNU} Automake}, for more
 information on Automake.
 
 @item Books
@@ -1080,7 +1080,7 @@ has been continually address@hidden
 i.e., expect one level of quotes to be lost.  For instance:
 
 @example
-AC_COMPILE_IFELSE([char b[10];],, [AC_MSG_ERROR([you lose])])
+AC_COMPILE_IFELSE([char b[10];], [], [AC_MSG_ERROR([you lose])])
 @end example
 
 @noindent
@@ -1092,7 +1092,7 @@ use it!)  Let's take a closer look: the 
 to be understood as a literal, and therefore it must be quoted twice:
 
 @example
-AC_COMPILE_IFELSE([[char b[10];]],, [AC_MSG_ERROR([you lose])])
+AC_COMPILE_IFELSE([[char b[10];]], [], [AC_MSG_ERROR([you lose])])
 @end example
 
 @noindent
@@ -1478,7 +1478,7 @@ Gettext supplies the @command{autopoint}
 infrastructure to a source package.  If you use @command{autopoint},
 your @file{configure.ac} should invoke both @code{AM_GNU_GETTEXT} and
 @code{AM_GNU_GETTEXT_VERSION(@var{gettext-version})}.  @xref{autopoint
-Invocation,, Invoking the @code{autopoint} Program, gettext, GNU
+Invocation, , Invoking the @code{autopoint} Program, gettext, GNU
 @code{gettext} utilities}, for further details.
 
 @noindent
@@ -2103,7 +2103,7 @@ distributed with a file @file{Makefile.i
 way, the user has to properly configure the package for the local system
 before compiling it.
 
address@hidden Conventions,, Makefile Conventions, standards, The
address@hidden Conventions, , Makefile Conventions, standards, The
 @acronym{GNU} Coding Standards}, for more information on what to put in
 @file{Makefile}s.
 
@@ -2295,7 +2295,7 @@ Absolute name of @code{top_srcdir}.
 @cindex Directories, installation
 
 The following variables specify the directories where the package will
-be installed, see @ref{Directory Variables,, Variables for
+be installed, see @ref{Directory Variables, , Variables for
 Installation Directories, standards, The @acronym{GNU} Coding
 Standards}, for more information.  See the end of this section for
 details on when and how to use these variables.
@@ -2663,7 +2663,7 @@ example, if it redefines @code{const}).
 To provide for VPATH builds, remember to pass the C compiler a @option{-I.}
 option (or @option{-I..}; whichever directory contains @file{config.h}).
 Even if you use @samp{#include "config.h"}, the preprocessor searches only
-the directory of the currently read file, address@hidden the source directory, 
not
+the directory of the currently read file, i.e., the source directory, not
 the build directory.
 
 With the appropriate @option{-I} option, you can use
@@ -3793,7 +3793,7 @@ tradition of it returning @code{int}.
 @item @code{free}
 @c @fuindex free
 @prindex @code{free}
-The ISO C99 standard says a call @code{free(NULL)} does nothing, but
+The C standard says a call @code{free (NULL)} does nothing, but
 some old systems don't support this (e.g., NextStep).
 
 @item @code{isinf}
@@ -3802,7 +3802,7 @@ some old systems don't support this (e.g
 @c @fuindex isnan
 @prindex @code{isinf}
 @prindex @code{isnan}
-The ISO C99 standard specifies that @code{isinf} and @code{isnan} are
+The C99 standard says that @code{isinf} and @code{isnan} are
 macros.  On some systems just macros are available (e.g., HP-UX), on
 some systems both macros and functions (e.g., glibc 2.3.2), and on some
 systems only functions (e.g., IRIX 6 and Solaris 9).  In some cases
@@ -3851,8 +3851,8 @@ probably not worth worrying about.
 @item @code{malloc}
 @c @fuindex malloc
 @prindex @code{malloc}
-The ISO C99 standard says a call @code{malloc(0)} is implementation
-dependent, it may either return @code{NULL} (e.g., OSF 4) or
+The C standard says a call @code{malloc (0)} is implementation
+dependent.  It may either return @code{NULL} (e.g., OSF 4) or
 address@hidden (e.g., @acronym{GNU} C Library).  @code{AC_FUNC_MALLOC}
 can be used to insist on address@hidden (@pxref{Particular Functions}).
 
@@ -3868,18 +3868,18 @@ Posix specifies that @code{putenv} puts 
 glibc 2.0, or BSD).  And when a copy is made, @code{unsetenv} might
 not free it, causing a memory leak (e.g., FreeBSD 4).
 
-On some systems @code{putenv("FOO")} removes @samp{FOO} from the
+On some systems @code{putenv ("FOO")} removes @samp{FOO} from the
 environment, but this is not standard usage and it dumps core
 on some systems (e.g., AIX).
 
-On MINGW, a call @code{putenv("FOO=")} removes @samp{FOO} from the
+On MINGW, a call @code{putenv ("FOO=")} removes @samp{FOO} from the
 environment, rather than inserting it with an empty value.
 
 @item @code{realloc}
 @c @fuindex realloc
 @prindex @code{realloc}
-The ISO C99 standard says a call @code{realloc(NULL,size)} is equivalent
-to a @code{malloc(size)}, but some old systems don't support this (e.g.,
+The C standard says a call @code{realloc (NULL, size)} is equivalent
+to @code{malloc (size)}, but some old systems don't support this (e.g.,
 NextStep).
 
 @item @code{signal} handler
@@ -3900,7 +3900,7 @@ used to establish the correct type in al
 @prindex @code{snprintf}
 @c @fuindex vsnprintf
 @prindex @code{vsnprintf}
-The ISO C99 standard says that if the output array isn't big enough
+The C99 standard says that if the output array isn't big enough
 and if no other errors occur, @code{snprintf} and @code{vsnprintf}
 truncate the output and return the number of bytes that ought to have
 been produced.  Some older systems return the truncated length (e.g.,
@@ -3915,7 +3915,7 @@ Solaris 7).
 @prindex @code{sprintf}
 @c @fuindex vsprintf
 @prindex @code{vsprintf}
-The ISO C standard says @code{sprintf} and @code{vsprintf} return the
+The C standard says @code{sprintf} and @code{vsprintf} return the
 number of bytes written, but on some ancient systems (SunOS 4 for
 instance) they return the buffer pointer instead.
 
@@ -3926,7 +3926,7 @@ On various old systems, e.g., HP-UX 9, @
 input string be writable (though it doesn't actually change it).  This
 can be a problem when using @command{gcc} since it normally puts
 constant strings in read-only memory
-(@pxref{Incompatibilities,Incompatibilities of GCC,,gcc,Using and
+(@pxref{Incompatibilities, Incompatibilities of GCC, , gcc, Using and
 Porting the @acronym{GNU} Compiler Collection}).  Apparently in some cases even
 having format strings read-only can be a problem.
 
@@ -3976,17 +3976,17 @@ and some @acronym{DOS} variants even cor
 @c @fuindex unsetenv
 @prindex @code{unsetenv}
 On MINGW, @code{unsetenv} is not available, but a variable @samp{FOO}
-can be removed with a call @code{putenv("FOO=")}, as described under
+can be removed with a call @code{putenv ("FOO=")}, as described under
 @code{putenv} above.
 
 @item @code{va_copy}
 @c @fuindex va_copy
 @prindex @code{va_copy}
-The ISO C99 standard provides @code{va_copy} for copying
+The C99 standard provides @code{va_copy} for copying
 @code{va_list} variables.  It may be available in older environments
 too, though possibly as @code{__va_copy} (e.g., @command{gcc} in strict
-C89 mode).  These can be tested with @code{#ifdef}.  A fallback to
address@hidden (&dst, &src, sizeof(va_list))} will give maximum
+pre-C99 mode).  These can be tested with @code{#ifdef}.  A fallback to
address@hidden (&dst, &src, sizeof (va_list))} will give maximum
 portability.
 
 @item @code{va_list}
@@ -4003,10 +4003,18 @@ value back in the caller (e.g., @code{vs
 @item Signed @code{>>}
 Normally the C @code{>>} right shift of a signed type replicates the
 high bit, giving a so-called ``arithmetic'' shift.  But care should be
-taken since the ISO C standard doesn't require that behavior.  On those
+taken since Standard C doesn't require that behavior.  On those
 few processors without a native arithmetic shift (for instance Cray
 vector systems) zero bits may be shifted in, the same as a shift of an
 unsigned type.
+
address@hidden Integer @code{/}
+C divides signed integers by truncating their quotient toward zero,
+yielding the same result as Fortran.  However, before C99 the standard
+allowed C implementations to take the floor or ceiling of the quotient
+in some cases.  Hardly any implementations took advantage of this
+freedom, though, and it's probably not worth worrying about this issue
+nowadays.
 @end table
 
 
@@ -4034,7 +4042,7 @@ If those attempts fail, it looks for the
 library.  If any of those methods succeed, it defines
 @code{HAVE_ALLOCA}.  Otherwise, it sets the output variable
 @code{ALLOCA} to @address@hidden@}alloca.o} and defines
address@hidden (so programs can periodically call @samp{alloca(0)} to
address@hidden (so programs can periodically call @samp{alloca (0)} to
 garbage collect).  This variable is separate from @code{LIBOBJS} so
 multiple programs can share the value of @code{ALLOCA} without needing
 to create an actual library, in case only some of them use the code in
@@ -4397,7 +4405,7 @@ If the obstacks are found, define @code{
 @c @fuindex realloc
 @prindex @code{realloc}
 If the @code{realloc} function is compatible with the @acronym{GNU} C
-library @code{realloc} (i.e., @samp{realloc (0, 0)} returns a
+library @code{realloc} (i.e., @samp{realloc (NULL, 0)} returns a
 valid pointer), define @code{HAVE_REALLOC} to 1.  Otherwise define
 @code{HAVE_REALLOC} to 0, ask for an @code{AC_LIBOBJ} replacement for
 @samp{realloc}, and define @code{realloc} to @code{rpl_realloc} so that
@@ -4524,7 +4532,7 @@ from @acronym{AIX} 4.3), require an @cod
 @cvindex HAVE_UTIME_NULL
 @c @fuindex utime
 @prindex @code{utime}
-If @samp{utime(@var{file}, NULL)} sets @var{file}'s timestamp to
+If @samp{utime (@var{file}, NULL)} sets @var{file}'s timestamp to
 the present, define @code{HAVE_UTIME_NULL}.
 @end defmac
 
@@ -4719,9 +4727,9 @@ additions.  Please help us keeping it as
 @item @file{inttypes.h} vs.@: @file{stdint.h}
 @hdrindex{inttypes.h}
 @hdrindex{stdint.h}
-Paul Eggert notes that: ISO C 1999 says that @file{inttypes.h} includes
+The C99 standard says that @file{inttypes.h} includes
 @file{stdint.h}, so there's no need to include @file{stdint.h}
-separately in a standard environment.  Many implementations have
+separately in a standard environment.  Some implementations have
 @file{inttypes.h} but not @file{stdint.h} (e.g., Solaris 7), but we don't
 know of any implementation that has @file{stdint.h} but not
 @file{inttypes.h}.
@@ -4848,12 +4856,13 @@ something like the following:
 
 @example
 @group
-#if HAVE_DIRENT_H
+#include <sys/types.h>
+#ifdef HAVE_DIRENT_H
 # include <dirent.h>
-# define NAMLEN(dirent) strlen((dirent)->d_name)
+# define NAMLEN(dirent) strlen ((dirent)->d_name)
 #else
 # define dirent direct
-# define NAMLEN(dirent) (dirent)->d_namlen
+# define NAMLEN(dirent) ((dirent)->d_namlen)
 # if HAVE_SYS_NDIR_H
 #  include <sys/ndir.h>
 # endif
@@ -5811,19 +5820,19 @@ features.  To check for characteristics 
 
 @defmac AC_PROG_CC_STDC
 @acindex{PROG_CC_STDC}
-If the C compiler is not able to compile ISO Standard C (currently ISO
-C99), try to add an option to output variable @code{CC} to make it so.
-If the compiler does not support ISO C99, fall back to supporting
address@hidden C89 (ISO C90).
+If the C compiler cannot compile @acronym{ISO} Standard C (currently
+C99), try to add an option to output variable @code{CC} to make it work.
+If the compiler does not support C99, fall back to supporting
address@hidden C89 (@acronym{ISO} C90).
 
 After calling this macro you can check whether the C compiler has been
-set to accept ISO Standard C; if not, the shell variable
+set to accept Standard C; if not, the shell variable
 @code{ac_cv_prog_cc_stdc} is set to @samp{no}.
 @end defmac
 
 @defmac AC_PROG_CC_C89
 @acindex{PROG_CC_C89}
-If the C compiler is not in @acronym{ANSI} C89 (ISO C90) mode by
+If the C compiler is not in @acronym{ANSI} C89 (@acronym{ISO} C90) mode by
 default, try to add an option to output variable @code{CC} to make it
 so.  This macro tries various options that select @acronym{ANSI} C89 on
 some system or another.  It considers the compiler to be in
@@ -5838,17 +5847,17 @@ This macro is called automatically by @c
 
 @defmac AC_PROG_CC_C99
 @acindex{PROG_CC_C99}
-If the C compiler is not in ISO C99 mode by default, try to add an
+If the C compiler is not in C99 mode by default, try to add an
 option to output variable @code{CC} to make it so.  This macro tries
-various options that select ISO C99 on some system or another.  It
-considers the compiler to be in ISO C99 mode if it handles @code{_Bool},
-flexible arrays, @code{inline}, @code{long long}, mixed code and
+various options that select C99 on some system or another.  It
+considers the compiler to be in C99 mode if it handles @code{_Bool},
+flexible arrays, @code{inline}, @code{long long int}, mixed code and
 declarations, named initialization of structs, @code{restrict}, varargs
 macros, variable declarations in @code{for} loops and variable length
 arrays.
 
 After calling this macro you can check whether the C compiler has been
-set to accept ISO C99; if not, the shell variable
+set to accept C99; if not, the shell variable
 @code{ac_cv_prog_cc_c99} is set to @samp{no}.
 @end defmac
 
@@ -6199,7 +6208,7 @@ should be include after @code{LIBS} when
 
 This macro is intended to be used in those situations when it is
 necessary to mix, e.g., C++ and Fortran source code in a single
-program or shared library (@pxref{Mixing Fortran 77 With C and C++,,,
+program or shared library (@pxref{Mixing Fortran 77 With C and C++, , ,
 automake, @acronym{GNU} Automake}).
 
 For example, if object files from a C++ and Fortran compiler must be
@@ -6213,8 +6222,8 @@ as well, but the C++ compiler/linker doe
 these Fortran 77 libraries.  Hence, this macro was created to determine
 these Fortran libraries.
 
-The macros @code{AC_F77_DUMMY_MAIN}/@code{AC_FC_DUMMY_MAIN} or
address@hidden/@code{AC_FC_MAIN} will probably also be necessary to
+The macros @code{AC_F77_DUMMY_MAIN} and @code{AC_FC_DUMMY_MAIN} or
address@hidden and @code{AC_FC_MAIN} will probably also be necessary to
 link C/C++ with Fortran; see below.
 @end defmac
 
@@ -6227,8 +6236,8 @@ With many compilers, the Fortran librari
 their own @code{main} entry function that initializes things like
 Fortran I/O, and which then calls a user-provided entry function named
 (say) @code{MAIN__} to run the user's program.  The
address@hidden/@code{AC_FC_DUMMY_MAIN} or
address@hidden/@code{AC_FC_MAIN} macro figures out how to deal with
address@hidden and @code{AC_FC_DUMMY_MAIN} or
address@hidden and @code{AC_FC_MAIN} macros figure out how to deal with
 this interaction.
 
 When using Fortran for purely numerical functions (no I/O, etc.)@: often
@@ -6276,15 +6285,15 @@ As discussed above, many Fortran librari
 point called (say) @code{MAIN__} instead of the usual @code{main}, which
 is then called by a @code{main} function in the Fortran libraries that
 initializes things like Fortran I/address@hidden  The
address@hidden/@code{AC_FC_MAIN} macro detects whether it is
address@hidden and @code{AC_FC_MAIN} macros detect whether it is
 @emph{possible} to utilize such an alternate main function, and defines
address@hidden/@code{FC_MAIN} to the name of the function.  (If no
-alternate main function name is found, @code{F77_MAIN}/@code{FC_MAIN} is
address@hidden and @code{FC_MAIN} to the name of the function.  (If no
+alternate main function name is found, @code{F77_MAIN} and @code{FC_MAIN} are
 simply defined to @code{main}.)
 
 Thus, when calling Fortran routines from C that perform things like I/O,
 one should use this macro and name the "main" function
address@hidden/@code{FC_MAIN} instead of @code{main}.
address@hidden or @code{FC_MAIN} instead of @code{main}.
 @end defmac
 
 @defmac AC_F77_WRAPPERS
@@ -6295,8 +6304,8 @@ one should use this macro and name the "
 @acindex{FC_WRAPPERS}
 @cvindex FC_FUNC
 @cvindex FC_FUNC_
-Defines C macros @code{F77_FUNC(name,NAME)}/@code{FC_FUNC(name,NAME)}
-and @code{F77_FUNC_(name,NAME)}/@code{FC_FUNC_(name,NAME)} to properly
+Defines C macros @code{F77_FUNC (name, NAME)}, @code{FC_FUNC (name, NAME)},
address@hidden(name, NAME)}, and @code{FC_FUNC_(name, NAME)} to properly
 mangle the names of C/C++ identifiers, and identifiers with underscores,
 respectively, so that they match the name-mangling scheme used by the
 Fortran compiler.
@@ -6311,7 +6320,7 @@ simply wraps all C identifiers in one of
 you have the following Fortran 77 subroutine:
 
 @example
-      subroutine foobar(x,y)
+      subroutine foobar (x, y)
       double precision x, y
       y = 3.14159 * x
       return
@@ -6321,7 +6330,7 @@ you have the following Fortran 77 subrou
 You would then declare its prototype in C or C++ as:
 
 @example
-#define FOOBAR_F77 F77_FUNC(foobar,FOOBAR)
+#define FOOBAR_F77 F77_FUNC (foobar, FOOBAR)
 #ifdef __cplusplus
 extern "C"  /* prevent C++ name mangling */
 #endif
@@ -6331,7 +6340,7 @@ void FOOBAR_F77(double *x, double *y);
 Note that we pass both the lowercase and uppercase versions of the
 function name to @code{F77_FUNC} so that it can select the right one.
 Note also that all parameters to Fortran 77 routines are passed as
-pointers (@pxref{Mixing Fortran 77 With C and C++,,, automake, @acronym{GNU}
+pointers (@pxref{Mixing Fortran 77 With C and C++, , , automake, @acronym{GNU}
 Automake}).
 
 (Replace @code{F77} with @code{FC} for Fortran instead of Fortran 77.)
@@ -6341,20 +6350,20 @@ name-mangling scheme of the Fortran comp
 compilers that it doesn't support yet.  In this case, the above code
 will generate a compile-time error, but some other behavior
 (e.g., disabling Fortran-related features) can be induced by checking
-whether the @code{F77_FUNC}/@code{FC_FUNC} macro is defined.
+whether @code{F77_FUNC} or @code{FC_FUNC} is defined.
 
 Now, to call that routine from a C program, we would do something like:
 
 @example
 @{
     double x = 2.7183, y;
-    FOOBAR_F77(&x, &y);
+    FOOBAR_F77 (&x, &y);
 @}
 @end example
 
 If the Fortran identifier contains an underscore (e.g., @code{foo_bar}),
-you should use @code{F77_FUNC_}/@code{FC_FUNC_} instead of
address@hidden/@code{FC_FUNC} (with the same arguments).  This is
+you should use @code{F77_FUNC_} or @code{FC_FUNC_} instead of
address@hidden or @code{FC_FUNC} (with the same arguments).  This is
 because some Fortran compilers mangle names differently if they contain
 an underscore.
 @end defmac
@@ -6704,7 +6713,7 @@ This macro runs only at @command{autocon
 layer language @footnote{Because M4 is not aware of Sh code,
 especially conditionals, some optimizations that look nice statically
 may produce incorrect results at runtime.}, the macros
address@hidden/@code{AC_LANG_POP} cannot be ``optimizing'',
address@hidden and @code{AC_LANG_POP} cannot be ``optimizing'',
 therefore as much as possible you ought to avoid using them to wrap
 your code, rather, require from the user to run the macro with a
 correct current language, and check it with @code{AC_LANG_ASSERT}.
@@ -9165,7 +9174,7 @@ AC_DEFUN(@var{macro-name}, @var{macro-bo
 @end example
 
 You can refer to any arguments passed to the macro as @samp{$1},
address@hidden, etc.  @xref{Definitions,, How to define new macros, m4.info,
address@hidden, etc.  @xref{Definitions, , How to define new macros, m4.info,
 @acronym{GNU} m4}, for more complete information on writing M4 macros.
 
 Be sure to properly quote both the @var{macro-body} @emph{and} the
@@ -9767,7 +9776,7 @@ required a single space between the @sam
 these are no longer of practical concern.
 
 The set of external programs you should run in a @command{configure} script
-is fairly small.  @xref{Utilities in Makefiles,, Utilities in
+is fairly small.  @xref{Utilities in Makefiles, , Utilities in
 Makefiles, standards, @acronym{GNU} Coding Standards}, for the list.  This
 restriction allows users to start out with a fairly small set of
 programs and build the rest, avoiding too many interdependencies between
@@ -9850,7 +9859,7 @@ Substitutions}, item ``Command Substitut
 To detect whether you are running Bash, test whether
 @code{BASH_VERSION} is set.  To require
 Posix compatibility, run @samp{set -o posix}.  @xref{Bash POSIX
-Mode,, Bash Posix Mode, bash, The @acronym{GNU} Bash Reference
+Mode, , Bash Posix Mode, bash, The @acronym{GNU} Bash Reference
 Manual}, for details.
 
 @item Bash 2.05 and later
@@ -9923,7 +9932,7 @@ To detect whether you are running @comma
 @code{ZSH_VERSION} is set.  By default @command{zsh} is @emph{not}
 compatible with the Bourne shell: you must execute @samp{emulate sh},
 and for @command{zsh} versions before 3.1.6-dev-18 you must also
-set @code{NULLCMD} to @samp{:}.  @xref{Compatibility,, Compatibility,
+set @code{NULLCMD} to @samp{:}.  @xref{Compatibility, , Compatibility,
 zsh, The Z Shell Manual}, for details.
 
 The default Mac OS X @command{sh} was originally Zsh; it was changed to
@@ -13116,7 +13125,7 @@ directory that was created in the curren
 
 @acronym{GNU} @command{make} uses a rather complex algorithm to decide when it
 should use files found via a @code{VPATH} search.  @xref{Search
-Algorithm,, How Directory Searches are Performed, make, The @acronym{GNU} Make
+Algorithm, , How Directory Searches are Performed, make, The @acronym{GNU} Make
 Manual}.
 
 If a target needs to be rebuilt, @acronym{GNU} @command{make} discards the
@@ -13136,7 +13145,7 @@ OpenBSD and FreeBSD @command{make}s, how
 This is extremely annoying.
 
 When attempting a @code{VPATH} build for an autoconfiscated package
-(e.g,, @code{mkdir build && cd build && ../configure}), this means the
+(e.g., @code{mkdir build && cd build && ../configure}), this means the
 @acronym{GNU}
 @command{make} will build everything locally in the @file{build}
 directory, while BSD @command{make} will build new files locally and
@@ -13930,7 +13939,7 @@ location such as the user's home directo
 by an environment variable.  The programs should examine that file at
 run time, rather than at compile time.  Run-time configuration is more
 convenient for users and makes the configuration process simpler than
-getting the information while configuring.  @xref{Directory Variables,,
+getting the information while configuring.  @xref{Directory Variables, ,
 Variables for Installation Directories, standards, @acronym{GNU} Coding
 Standards}, for more information on where to put data files.
 
@@ -15595,7 +15604,7 @@ quoted:
 
 @example
 AC_INIT
-AC_CHECK_HEADERS(foo.h,,
+AC_CHECK_HEADERS(foo.h, ,
   AC_MSG_ERROR(cannot find foo.h, bailing out))
 AC_OUTPUT
 @end example