Re: proposed gnulib-related additions to Autoconf

[Ralf Wildenhues]

Hi Paul,

* Paul Eggert wrote on Wed, Mar 01, 2006 at 01:48:54AM CET:
> Several macros in Gnulib really belong in Autoconf.  I took a first
> cut at migrating the code, and came up with the following proposed
> patch to Autoconf.  Not all the gnulib macros made the cut, and some
> needed to be renamed to avoid backwards-compatibility issues and to
> keep the naming conventions.  Comments welcome.

First quick review below, snipping everything but interesting patch
hunks including file headers.

Great work BTW!

Cheers,
Ralf

> Index: doc/autoconf.texi
> ===================================================================
> RCS file: /cvsroot/autoconf/autoconf/doc/autoconf.texi,v
> retrieving revision 1.954
> diff -p -u -r1.954 autoconf.texi
> --- doc/autoconf.texi 22 Feb 2006 20:18:23 -0000      1.954
> +++ doc/autoconf.texi 1 Mar 2006 00:45:24 -0000

> @@ -749,6 +753,31 @@ The benefits of Automake increase for la
>  with subdirectories), but even for small programs the added convenience
>  and portability can be substantial.  And that's not address@hidden
> 
> address@hidden Gnulib
> address@hidden Gnulib

Please add a @cindex entry for Gnulib.

> +
> address@hidden software has a well-deserved reputation for running on
> +many different types of systems.  While our primary goal is to write
> +software for the @acronym{GNU} system, many users and developers have
> +been introduced to us through the systems that they were already using.
> +
> +Gnulib is a central location for common @acronym{GNU} code, intended to
> +be shared among free-software packages.  Its components are typically

I'd write  s|free-|free |  as done elsewhere in the documentation.

> +shared at the source level, rather than being a library that gets built,
> +installed, and linked against.  The idea is to copy files from Gnulib
> +into your own source tree.  There is no distribution tarball; developers
> +should just grab source modules from the repository.  The source files
> +are available online, under various licences, mostly GNU GPL or GNU
> +LGPL.
> +
> +Gnulib modules typically contain C source code along with Autoconf
> +macros used to configure the source code.  For example, the Gnulib
> address@hidden module implements a @file{stdbool.h} header that nearly
> +conforms to C99, even on old-fashioned hosts that lack @file{stdbool.h}.
> +This module contains a source file for the replacement header, along
> +with an Autoconf macro that arranges to use the replacement header on
> +old-fashioned systems.
> +
>  @node Libtool
>  @section Libtool


> @@ -796,7 +825,8 @@ the @acronym{GNU} build tools.
>  
>  The home pages for
>  @uref{http://www.gnu.org/software/autoconf/, Autoconf},
> address@hidden://www.gnu.org/software/automake/, Automake}, and
> address@hidden://www.gnu.org/software/automake/, Automake},
> address@hidden://www.gnu.org/software/automake/, Gnulib}, and
>  @uref{http://www.gnu.org/software/libtool/, Libtool}.
>  
>  @item Automake Manual

s|automake/, Gnulib|gnulib/, Gnulib|

> @@ -5573,6 +5911,22 @@ compatibility, a simple heuristics, quit
>  implemented.  In case of doubt, read the documentation of the former
>  @code{AC_CHECK_TYPE}, see @ref{Obsolete Macros}.
>  
> address@hidden Ranges of Integer Types
> address@hidden Checks for Ranges of Integer Types
> +
> +This macro checks for ranges of integer types not covered by the
> +``particular'' test macros.
> +
> address@hidden AC_C_TYPE_RANGE_INTEGER (@var{type}, @ovar{min-variable}, 
> @var{max-variable}, @dvar{includes, default-includes})
> address@hidden
> +Compute the bounds of the integer @var{type} and define
> address@hidden and @var{max-variable} to integer constant
> +expressions that suitable for use even in the preprocessor.  Do not
> +define @var{min-variable} if it is absent.  Do not define either
> +variable if it is already defined by @var{includes}, or if @var{type} is
> +not a valid type.
> address@hidden defmac
> +
>  
>  @node Compilers and Preprocessors
>  @section Compilers and Preprocessors

s|that|& are|


> Index: lib/autoconf/c.m4
> ===================================================================
> RCS file: /cvsroot/autoconf/autoconf/lib/autoconf/c.m4,v
> retrieving revision 1.210
> diff -p -u -r1.210 c.m4
> --- lib/autoconf/c.m4 24 Jan 2006 00:20:15 -0000      1.210
> +++ lib/autoconf/c.m4 1 Mar 2006 00:45:24 -0000

> @@ -1121,39 +1121,18 @@ fi
>  
>  # AC_C_LONG_DOUBLE
>  # ----------------
> -AC_DEFUN([AC_C_LONG_DOUBLE],
> -[AC_CACHE_CHECK(
> -   [for working long double with more range or precision than double],
> -   [ac_cv_c_long_double],
> -   [AC_COMPILE_IFELSE(
> -      [AC_LANG_BOOL_COMPILE_TRY(
> -      [[#include <float.h>
> -        long double const a[] =
> -          {
> -             0.0L, DBL_MIN, DBL_MAX, DBL_EPSILON,
> -             LDBL_MIN, LDBL_MAX, LDBL_EPSILON
> -          };
> -        long double
> -        f (long double x)
> -        {
> -           return ((x + (unsigned long int) 10) * (-1 / x) + a[0]
> -                    + (x ? f (x) : 'c'));
> -        }
> -      ]],
> -      [[(0 < ((DBL_MAX_EXP < LDBL_MAX_EXP)
> -               + (DBL_MANT_DIG < LDBL_MANT_DIG)
> -               - (LDBL_MAX_EXP < DBL_MAX_EXP)
> -               - (LDBL_MANT_DIG < DBL_MANT_DIG)))
> -        && (int) LDBL_EPSILON == 0
> -         ]])],
> -      ac_cv_c_long_double=yes,
> -      ac_cv_c_long_double=no)])
> -if test $ac_cv_c_long_double = yes; then
> -  AC_DEFINE(HAVE_LONG_DOUBLE, 1,
> -         [Define to 1 if long double works and has more range or precision 
> than double.])
> -fi
> -])# AC_C_LONG_DOUBLE
> -
> +AU_DEFUN([AC_C_LONG_DOUBLE],
> +  [
> +    AC_TYPE_LONG_DOUBLE_WIDER
> +    if test $ac_cv_type_long_double_wider = yes; then
> +      AC_DEFINE([HAVE_LONG_DOUBLE], 1,
> +     [Define to 1 if the type `long double' works and has more range or
> +      precision than `double'.])
> +    fi
> +  ],
> +  [The macro `AC_C_LONG_DOUBLE' is obsolete.
> +You should use `AC_TYPE_LONG_DOUBLE' or `AC_TYPE_LONG_DOUBLE_WIDER' instead.]
> +)
>  
>  # AC_C_BIGENDIAN ([ACTION-IF-TRUE], [ACTION-IF-FALSE], [ACTION-IF-UNKNOWN])
>  # -------------------------------------------------------------------------

The AU_DEFUN of AC_C_LONG_DOUBLE is repeated in lib/autoconf/types.m4.

I fear a bit that external code may rely on $ac_cv_c_long_double.

> @@ -1471,3 +1450,120 @@ AC_DEFUN([AC_C_TYPEOF],
>      fi
>    fi
>  ])
> +
> +
> +# AC_C_TYPE_RANGE_INTEGER(TYPE, [MIN-VARIABLE], MAX-VARIABLE,
> +#                      [INCLUDES = DEFAULT-INCLUDES])
> +# -----------------------------------------------------------
> +# Compute the bounds of the integer TYPE and define MIN-VARIABLE and
> +# MAX-VARIABLE to those bounds.  The bounds are expressions that are
> +# suitable for use in the preprocessor.  If MIN-VARIABLE is absent, do
> +# not define it.  If either variable is already defined by INCLUDES, do
> +# not define it.  If TYPE does not work, do not define either variable.
> +# Works OK if cross compiling.
> +m4_define([AC_C_TYPE_RANGE_INTEGER],

Why is this m4_define'd and not AC_DEFUN'd?

> +[
> +  AC_CACHE_CHECK([for $3], [ac_cv_value_$3],
> +    [ac_cv_value_$3=no
> +     ac_signbits=
> +     AC_COMPILE_IFELSE(
> +       [AC_LANG_BOOL_COMPILE_TRY([AC_INCLUDES_DEFAULT([$4])], [($1) -1 < 
> 0])],
> +       [ac_signbits=1; ac_suffix=; ac_unsigned=],
*snip*



> Index: lib/autoconf/functions.m4
> ===================================================================
> RCS file: /cvsroot/autoconf/autoconf/lib/autoconf/functions.m4,v
> retrieving revision 1.95
> diff -p -u -r1.95 functions.m4
> --- lib/autoconf/functions.m4 24 Jan 2006 00:20:15 -0000      1.95
> +++ lib/autoconf/functions.m4 1 Mar 2006 00:45:24 -0000

> @@ -1500,6 +1526,36 @@ fi
>  ])
>  
>  
> +# AC_FUNC_STRTOLD
> +# ---------------
> +AC_DEFUN([AC_FUNC_STRTOLD],
> +[
> +  AC_CACHE_CHECK([whether strtold conforms to C99],
> +    [ac_cv_func_strtold],
> +    [AC_COMPILE_IFELSE(
> +       [AC_LANG_PROGRAM(
> +       [[/* On HP-UX before 11.23, strtold returns a struct instead of
> +             long double.  Reject implementations like that, by requiring
> +             compatibility with the C99 prototype.  */
> +          #include <stdlib.h>

Doesn't Autoconf code still put the hash in the first column?

> +          static long double (*p) (char const *, char **) = strtold;
> +          static long double
> +          test (char const *nptr, char **endptr)
> +          {
> +            long double r;
> +            r = strtold (nptr, endptr);
> +            return r;
> +          }]],
> +        [[return test ("1.0", NULL) != 1 || p ("1.0", NULL) != 1;]])],
> +       [ac_cv_func_strtold=yes],
> +       [ac_cv_func_strtold=no])])
> +  if test $ac_cv_func_strtold = yes; then
> +    AC_DEFINE([HAVE_STRTOLD], 1,
> +      [Define to 1 if strtold exists and conforms to C99.])
> +  fi
> +])
> +
> +
>  # AU::AM_FUNC_STRTOD
>  # ------------------
>  AU_ALIAS([AM_FUNC_STRTOD], [AC_FUNC_STRTOD])

> Index: lib/autoconf/headers.m4
> ===================================================================
> RCS file: /cvsroot/autoconf/autoconf/lib/autoconf/headers.m4,v
> retrieving revision 1.45
> diff -p -u -r1.45 headers.m4
> --- lib/autoconf/headers.m4   24 Jan 2006 00:20:15 -0000      1.45
> +++ lib/autoconf/headers.m4   1 Mar 2006 00:45:24 -0000

> @@ -65,8 +65,8 @@
>  
>  
>  # AC_CHECK_HEADER(HEADER-FILE,
> -#                 [ACTION-IF-FOUND], [ACTION-IF-NOT-FOUND],
> -#                 [INCLUDES])
> +#              [ACTION-IF-FOUND], [ACTION-IF-NOT-FOUND],
> +#              [INCLUDES])
>  # ---------------------------------------------------------
>  # We are slowly moving to checking headers with the compiler instead
>  # of the preproc, so that we actually learn about the usability of a

Not sure if I like all those white space changes (several instances in
several files) introducing TABs in comments, and making this patch much
larger than necessary (and more difficult to review for lined-up
underlines ;-)

> @@ -207,6 +207,26 @@ done
>  ])# AC_CHECK_HEADERS
>  
>  
> +# AC_CHECK_HEADERS_ONCE(HEADER-FILE...)
> +# -------------------------------------
> +AC_DEFUN([AC_CHECK_HEADERS_ONCE],
> +[
> +  AH_CHECK_HEADERS([$1])
> +  m4_foreach_w([AC_Header], [$1],
> +    [AC_DEFUN([_AC_Header_]m4_quote(translit(AC_Header, [./-], [___])),
> +       [m4_divert_text([INIT_PREPARE],
> +       [ac_header_list="$ac_header_list AC_Header"])
> +     _AC_HEADERS_EXPANSION])
> +     AC_REQUIRE([_AC_Header_]m4_quote(translit(AC_Header, [./-], [___])))])

Please  s|translit|m4_&|, two instances.

> +])
> +m4_define([_AC_HEADERS_EXPANSION],
> +[
> +  m4_divert_text([DEFAULTS], [ac_header_list=])
> +  AC_CHECK_HEADERS([$ac_header_list])
> +  m4_define([_AC_HEADERS_EXPANSION], [])
> +])
> +
> +
>  
>  
>  ## --------------------- ##

> @@ -561,10 +594,39 @@ AC_DEFUN([AC_HEADER_STDBOOL],
>       enum { j = false, k = true, l = false * true, m = true * 256 };
>       _Bool n[m];
>       char o[sizeof n == m * sizeof n[0] ? 1 : -1];
> +     char p[-1 - (_Bool) 0 < 0 && -1 - (bool) 0 < 0 ? 1 : -1];
> +     #if defined __xlc__ || defined __GNUC__

See above (hash column).

> +      /* Catch a bug in IBM AIX xlc compiler version 6.0.0.0
> +         reported by James Lemley on 2005-10-05; see
> +         
> http://lists.gnu.org/archive/html/bug-coreutils/2005-10/msg00086.html
> +         This test is not quite right, since xlc is allowed to
> +         reject this program, as the initializer for xlcbug is
> +         not one of the forms that C requires support for.
> +         However, doing the test right would require a run-time
> +         test, and that would make cross-compilation harder.
> +         Let us hope that IBM fixes the xlc bug, and also adds
> +         support for this kind of constant expression.  In the
> +         meantime, this test will reject xlc, which is OK, since
> +         our stdbool.h substitute should suffice.  We also test
> +         this with GCC, where it should work, to detect more
> +         quickly whether someone messes up the test in the
> +         future.  */
> +      char digs[] = "0123456789";
> +      int xlcbug = 1 / (&(digs + 5)[-2 + (bool) 1] == &digs[4] ? 1 : -1);
> +     #endif

See above (hash column).

> +     /* Catch a bug in an HP-UX C compiler.  See
> +        http://gcc.gnu.org/ml/gcc-patches/2003-12/msg02303.html
> +        http://lists.gnu.org/archive/html/bug-coreutils/2005-11/msg00161.html
> +      */
> +     _Bool q = true;
> +     _Bool *pq = &q;
>        ]],
>        [[
> -      return (!a + !b + !c + !d + !e + !f + !g + !h + !i + !j + !k + !l
> -              + !m + !n + !o);
> +     *pq |= q;
> +     *pq |= ! q;
> +     /* Refer to every declared value, to avoid compiler optimizations.  */
> +     return (!a + !b + !c + !d + !e + !f + !g + !h + !i + !!j + !k + !!l
> +             + !m + !n + !o + !p + !q + !pq);
>        ]])],
>        [ac_cv_header_stdbool_h=yes],
>        [ac_cv_header_stdbool_h=no])])


> Index: lib/autoconf/specific.m4
> ===================================================================
> RCS file: /cvsroot/autoconf/autoconf/lib/autoconf/specific.m4,v
> retrieving revision 1.363
> diff -p -u -r1.363 specific.m4
> --- lib/autoconf/specific.m4  24 Jan 2006 00:20:15 -0000      1.363
> +++ lib/autoconf/specific.m4  1 Mar 2006 00:45:24 -0000

> @@ -379,6 +379,41 @@ esac
>  matches *mingw32*])# AC_MINGW32
>  
>  
> +# AC_USE_SYSTEM_EXTENSIONS
> +# ------------------------
> +# Enable extensions on systems that normally disable them,
> +# typically due to standards-conformance issues.
> +AC_DEFUN([AC_USE_SYSTEM_EXTENSIONS],
> +[
> +  AC_BEFORE([$0], [AC_COMPILE_IFELSE])
> +  AC_BEFORE([$0], [AC_RUN_IFELSE])
> +
> +  AC_REQUIRE([AC_GNU_SOURCE])
> +  AC_REQUIRE([AC_AIX])
> +  AC_REQUIRE([AC_MINIX])

It'd be nice to  s|$|dnl|  for all the AC_REQUIRE and AC_BEFORE.

> +
> +  AH_VERBATIM([__EXTENSIONS__],
> +[/* Enable extensions on Solaris.  */
> +#ifndef __EXTENSIONS__
> +# undef __EXTENSIONS__
> +#endif
> +#ifndef _POSIX_PTHREAD_SEMANTICS
> +# undef _POSIX_PTHREAD_SEMANTICS
> +#endif])
> +  AC_CACHE_CHECK([whether it is safe to define __EXTENSIONS__],
> +    [ac_cv_safe_to_define___extensions__],
> +    [AC_COMPILE_IFELSE(
> +       [AC_LANG_PROGRAM([
> +       #define __EXTENSIONS__ 1

See above (hash column).

> +       AC_INCLUDES_DEFAULT])],
> +       [ac_cv_safe_to_define___extensions__=yes],
> +       [ac_cv_safe_to_define___extensions__=no])])
> +  test $ac_cv_safe_to_define___extensions__ == yes &&
> +    AC_DEFINE([__EXTENSIONS__])
> +  AC_DEFINE([_POSIX_PTHREAD_SEMANTICS])
> +])
> +
> +
>  
>  
>  ## -------------------------- ##