guile/libguile/gen-scmconfig.c

/* Copyright 2003-2013, 2018, 2020-2022
     Free Software Foundation, Inc.

   This file is part of Guile.

   Guile is free software: you can redistribute it and/or modify it
   under the terms of the GNU Lesser General Public License as published
   by the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.

   Guile is distributed in the hope that it will be useful, but WITHOUT
   ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
   License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with Guile.  If not, see
   <https://www.gnu.org/licenses/>.  */

/**********************************************************************

  Description of Guile's public config header mechanics:
  -----------------------------------------------------

  Guile has three core headers:

    config.h: Guile's private automatically generated configuration
      header -- generated by configure.in and autoheader.  *NOT*
      installed during "make install" and so may not be referred to by
      any public headers.

      installed.  It's only visible to the libguile sources
      themselves, and it includes config.h, the private config header.
      Among other things this file provides a place to make decisions
      based on the information gathered in config.h.

    libguile/scmconfig.h: Guile's public automatically generated
      configuration header -- generated at build time by concatenating
      the contents of libguile/scmconfig.h.top with the output from
      libguile/gen-scmconfig.  gen-scmconfig bases its output on the
      information in the private config.h header, the contents of
      gen-scmconfig.h (which is created by configure.in from
      gen-scmconfig.h.in), and the information provided in this file,
      gen-scmconfig.c.

    libguile/scm.h: Guile's public core header.  This file is
      installed and publically visible.  It includes
      libguile/scmconfig.h, the public config header and provides a
      place to make decisions based on the information gathered in
      scmconfig.h to define things that other headers can depend on.

   Notes and guidelines:

   - use 1 and 0 for public #defines instead of "def and undef",
     i.e. use #define SCM_HAVE_FOO rather than just not defining
     SCM_HAVE_FOO whenever possible.  See GNU Coding Guidelines for
     rationale.  The only notable non-deprecated exception to this rule
     is GUILE_DEBUG which does not follow this convention in order to
     retain backward compatibility.

   - in the code below, be *VERY* careful not to use or rely on any
     runtime-dynamic information below.  For example, you cannot use
     sizeof (FOO), but must use static information like SIZEOF_BAR
     (from config.h) or SCM_SIZEOF_BAZ (from scmconfig.h).  This is
     because the gcc that is compiling gen-scmconfig.c and/or the
     machine that is running gen-scmconfig may not be the same
     compiler and/or hardware that will eventually be running Guile.
     (i.e. keep the cross-compilation case in mind).

   - try to avoid adding names to the public namespace when possible.
     Note in the code below, that in a number of cases, we detect a
     feature and based on that, we decide whether or not to print
     anything at all.  This decreases the extraneous #defines and
     #ifdefery that we require in scmconfig.h

   - try to avoid adding any duplicate definitions to config.h and
     scmconfig.h.  i.e. have just SCM_ENABLE_ELISP in scmconfig.h
     rather than ENABLE_ELISP in config.h and SCM_ENABLE_ELISP in
     scmconfig.h.

   - in cases where you need to communicate information from
     configure.in to gen-scmconfig.c, don't add an AC_DEFINE unless
     you need it for other purposes.  Just add a suitable SCM_I_GSC_*
     variable to configure.in, set the value, AC_SUBST the value, and
     add an appropriate line to gen-scmconfig.h.in.  All gen-scmconfig
     related AC_SUBST vars should be prefixed with SCM_I_GSC_.

   - make sure that anything that we explicitly typedef publically is
     prefixed with scm_t_.  i.e. we used to typedef long to ptrdiff_t
     if we didn't detect ptrdiff_t, but this has been changed so that
     we typedef ptrdiff_t instead so that we won't conflict with
     any non-guile header definitions of the same type.  For types
     like intptr_t and uintptr_t which we just try to detect and don't
     actually define, it's fine not to have a corresponding scm_t_
     type.

   - we now use SCM_SIZEOF_FOO != 0 rather than SCM_HAVE_FOO for any
     cases where the size might actually vary.

   Rationales (not finished):

     Why do we use a C program here rather than AC_OUTPUT_COMMANDS?
     --------------------------------------------------------------

     The main reason is that there are some values we would need
     access to at AC_OUTPUT_COMMANDs that are determined by configure
     but are not available at AC_OUTPUT time.  The values are *only*
     available via config.h.  We use gen-scmconfig so we can see those
     values and make decisions based on their settings.

     Why have gen-scmconfig.h.in?
     ----------------------------

     Without that header, we could end up needing multiple aliases for
     public settings like SCM_ENABLE_ELISP.  We can't define
     SCM_ENABLE_ELISP in config.h since that header is private and any
     definition in scmconfig.h would conflict (#ifndef might be
     possible but runs the risk of conflicting directives), so a
     likely solution would be to AC_DEFINE([SCM_I_ENABLE_ELISP]), and
     then use SCM_I_ENABLE_ELISP in gen-scmconfig via config.h to
     determine whether or not to #define SCM_ENABLE_ELISP, but this
     leaves us with two #defined symbols for each public setting --
     better to just have one value (public or private) that all code
     uses.

     Having this header means we can AC_SUBST a value like
     SCM_I_GSC_ENABLE_ELISP and then set it in here via AC_OUTPUT
     substitutions, and gen-scmconfig can use that definition to
     determine whether or not to #define SCM_ENABLE_ELISP when
     generating scmconfig.h, and we end up with nothing extraneous
     added to config.h.

 **********************************************************************/

#ifdef HAVE_CONFIG_H
#  include <config.h>
#endif

#include <stdint.h>
#include <stddef.h>
#include <stdio.h>
#include <string.h>

#include "gen-scmconfig.h"

#define pf printf

int
main (int argc, char *argv[])
{
  pf ("/* This file is automatically generated --"
      " see configure.in for details */\n"
      "\n"
      "#ifndef SCM_SCMCONFIG_H\n"
      "#define SCM_SCMCONFIG_H\n");

  /*** various important headers ***/
  pf ("\n");
  pf ("/* Important headers */\n");
  pf ("#include <stdint.h>\n");
  pf ("#include <stddef.h>\n");
  pf ("#include <limits.h>\n");

#if HAVE_SYS_TIME_H
  pf ("#include <sys/time.h>\n");
#else
  pf ("/* sys/time.h not available */\n");
#endif

  pf ("#include <time.h>\n");
  pf("\n");

  pf ("#include <stdlib.h>\n");
# ifdef HAVE_SYS_TYPES_H
  pf ("#include <sys/types.h>\n");
# endif
# ifdef HAVE_SYS_STDTYPES_H
  pf ("#include <sys/stdtypes.h>\n");
# endif
  pf ("#include <stddef.h>\n");

  pf("\n");
#ifdef HAVE_SYS_SELECT_H
  pf ("#define SCM_HAVE_SYS_SELECT_H 1 /* 0 or 1 */\n");
#else
  pf ("#define SCM_HAVE_SYS_SELECT_H 0 /* 0 or 1 */\n");
#endif

#ifdef HAVE_WINSOCK2_H
  pf ("#define SCM_HAVE_WINSOCK2_H 1 /* 0 or 1 */\n");
#else
  pf ("#define SCM_HAVE_WINSOCK2_H 0 /* 0 or 1 */\n");
#endif

  /*** GUILE_DEBUG (defined or undefined) ***/
  pf ("\n");
  pf ("/* Define to include various undocumented debugging functions. */\n");
  if (SCM_I_GSC_GUILE_DEBUG)
    pf ("#define GUILE_DEBUG 1 /* defined or undefined */\n");
  else
    pf ("/* #undef GUILE_DEBUG */\n");

  /*** SCM_ENABLE_DEPRECATED (0 or 1) ***/
  pf ("\n");
  pf ("/* Set to 1 if you want to enable deprecated features. */\n");
  pf ("/* (value will be 0 or 1). */\n");
  pf ("#define SCM_ENABLE_DEPRECATED %d\n", SCM_I_GSC_ENABLE_DEPRECATED);

  /*** SCM_STACK_GROWS_UP (0 or 1) ***/
  pf ("\n");
  pf ("/* Set to 1 if the stack grows up, 0 otherwise. */\n");
  pf ("#define SCM_STACK_GROWS_UP %d /* 0 or 1 */\n",
      SCM_I_GSC_STACK_GROWS_UP);

  /*** SCM_C_INLINE (defined to appropriate string or undefined) ***/
  pf ("\n");
  pf ("/* C compiler's syntax for inline functions if any,\n"
      "   otherwise undefined. */\n");
  if (SCM_I_GSC_C_INLINE)
    pf ("#define SCM_C_INLINE %s\n", SCM_I_GSC_C_INLINE);
  else
    pf ("/* #undef SCM_C_INLINE */\n");

  pf ("\n");
  pf ("/* Standard types. */\n");

  pf ("#define SCM_SIZEOF_CHAR %d\n", SIZEOF_CHAR);
  pf ("#define SCM_SIZEOF_UNSIGNED_CHAR %d\n", SIZEOF_UNSIGNED_CHAR);
  pf ("#define SCM_SIZEOF_SHORT %d\n", SIZEOF_SHORT);
  pf ("#define SCM_SIZEOF_UNSIGNED_SHORT %d\n", SIZEOF_UNSIGNED_SHORT);
  pf ("#define SCM_SIZEOF_LONG %d\n", SIZEOF_LONG);
  pf ("#define SCM_SIZEOF_UNSIGNED_LONG %d\n", SIZEOF_UNSIGNED_LONG);
  pf ("#define SCM_SIZEOF_INT %d\n", SIZEOF_INT);
  pf ("#define SCM_SIZEOF_UNSIGNED_INT %d\n", SIZEOF_UNSIGNED_INT);
  pf ("#define SCM_SIZEOF_SIZE_T %d\n", SIZEOF_SIZE_T);
  pf ("#define SCM_SIZEOF_LONG_LONG %d\n", SIZEOF_LONG_LONG);
  pf ("#define SCM_SIZEOF_UNSIGNED_LONG_LONG %d\n", SIZEOF_UNSIGNED_LONG_LONG);
  pf ("#define SCM_SIZEOF_INTMAX %d\n", SIZEOF_INTMAX_T);
  pf ("#define SCM_SIZEOF_SCM_T_PTRDIFF %d\n", SIZEOF_PTRDIFF_T);
  pf ("#define SCM_SIZEOF_INTPTR_T %d\n", SIZEOF_INTPTR_T);
  pf ("#define SCM_SIZEOF_UINTPTR_T %d\n", SIZEOF_UINTPTR_T);

  pf ("\n");
  pf ("/* same as POSIX \"struct timespec\" -- always defined */\n");
#ifdef HAVE_SYSTEM_STRUCT_TIMESPEC
  pf ("typedef struct timespec scm_t_timespec;\n");
#else
  pf ("/* POSIX.4 structure for a time value.  This is like a `struct timeval'"
      "   but has nanoseconds instead of microseconds.  */\n");
  pf ("typedef struct\n"
      "{\n"
      "  long int tv_sec;		/* Seconds.  */\n"
      "  long int tv_nsec;		/* Nanoseconds.  */\n"
      "} scm_t_timespec;\n");
#endif

  pf ("\n");
  pf ("/*** Threading model (scmconfig.h support not finished) ***/\n");

  pf ("/* Define to 1 if using pthread multithreading. */\n");
  pf ("#define SCM_USE_PTHREAD_THREADS %d /* 0 or 1 */\n",
      SCM_I_GSC_USE_PTHREAD_THREADS);

  pf ("/* Define to 1 if using one-thread 'multi'threading. */\n");
  pf ("#define SCM_USE_NULL_THREADS %d /* 0 or 1 */\n",
      SCM_I_GSC_USE_NULL_THREADS);

  pf ("/* Define to 1 if need braces around PTHREAD_ONCE_INIT (for Solaris). */\n");
  pf ("#define SCM_NEED_BRACES_ON_PTHREAD_ONCE_INIT %d /* 0 or 1 */\n",
      SCM_I_GSC_NEED_BRACES_ON_PTHREAD_ONCE_INIT);

  pf ("/* Define to 1 if need braces around PTHREAD_MUTEX_INITIALIZER\n"
      "   (for IRIX with GCC)  */\n");
  pf ("#define SCM_NEED_BRACES_ON_PTHREAD_MUTEX_INITIALIZER %d /* 0 or 1 */\n",
      SCM_I_GSC_NEED_BRACES_ON_PTHREAD_MUTEX_INITIALIZER);

#ifdef HAVE_PTHREAD_SIGMASK
  pf ("#define SCM_HAVE_PTHREAD_SIGMASK 1 /* 0 or 1 */\n");
#else
  pf ("#define SCM_HAVE_PTHREAD_SIGMASK 0 /* 0 or 1 */\n");
#endif

#ifdef HAVE_GC_PTHREAD_CANCEL
  pf ("#define SCM_HAVE_GC_PTHREAD_CANCEL 1 /* 0 or 1 */\n");
#else
  pf ("#define SCM_HAVE_GC_PTHREAD_CANCEL 0 /* 0 or 1 */\n");
#endif

#ifdef HAVE_GC_PTHREAD_EXIT
  pf ("#define SCM_HAVE_GC_PTHREAD_EXIT 1 /* 0 or 1 */\n");
#else
  pf ("#define SCM_HAVE_GC_PTHREAD_EXIT 0 /* 0 or 1 */\n");
#endif

#ifdef HAVE_GC_PTHREAD_SIGMASK
  pf ("#define SCM_HAVE_GC_PTHREAD_SIGMASK 1 /* 0 or 1 */\n");
#else
  pf ("#define SCM_HAVE_GC_PTHREAD_SIGMASK 0 /* 0 or 1 */\n");
#endif

  pf ("\n\n/*** File system access ***/\n");

  pf ("/* Define to 1 if `struct dirent64' is available.  */\n");
  pf ("#define SCM_HAVE_STRUCT_DIRENT64 %d /* 0 or 1 */\n",
      SCM_I_GSC_HAVE_STRUCT_DIRENT64);

  pf ("/* Define to 1 if `readdir64_r ()' is available.  */\n");
#ifdef HAVE_READDIR64_R
  pf ("#define SCM_HAVE_READDIR64_R 1 /* 0 or 1 */\n");
#else
  pf ("#define SCM_HAVE_READDIR64_R 0 /* 0 or 1 */\n");
#endif

  /* Arrange so that we have a file offset type that reflects the one
     used when compiling Guile, regardless of what the application's
     `_FILE_OFFSET_BITS' says.  See
     http://lists.gnu.org/archive/html/bug-guile/2009-06/msg00018.html
     for the original bug report.

     Note that we can't define `scm_t_off' in terms of `off_t' or
     `off64_t' because they may or may not be available depending on
     how the application that uses Guile is compiled.  */

#if defined GUILE_USE_64_CALLS && defined HAVE_STAT64
  pf ("typedef int64_t scm_t_off;\n");
  pf ("#define SCM_T_OFF_MAX INT64_MAX\n");
  pf ("#define SCM_T_OFF_MIN INT64_MIN\n");
#elif SIZEOF_OFF_T == SIZEOF_INT
  pf ("typedef int scm_t_off;\n");
  pf ("#define SCM_T_OFF_MAX INT_MAX\n");
  pf ("#define SCM_T_OFF_MIN INT_MIN\n");
#else
  pf ("typedef long int scm_t_off;\n");
  pf ("#define SCM_T_OFF_MAX LONG_MAX\n");
  pf ("#define SCM_T_OFF_MIN LONG_MIN\n");
#endif

  pf ("/* Define to 1 if the compiler supports the "
      "`__thread' storage class.  */\n");
  if (SCM_I_GSC_HAVE_THREAD_STORAGE_CLASS)
    pf ("#define SCM_HAVE_THREAD_STORAGE_CLASS\n");
  else
    pf ("/* #undef SCM_HAVE_THREAD_STORAGE_CLASS */\n");

#ifdef USE_DLL_IMPORT
  pf ("\n");
  pf ("/* Define some additional CPP macros on Win32 platforms. */\n");
  pf ("# define __REGEX_IMPORT__ 1\n");
  pf ("# define __CRYPT_IMPORT__ 1\n");
  pf ("# define __READLINE_IMPORT__ 1\n");
  pf ("# define QT_IMPORT 1\n");
#endif

  pf ("\n");
  pf ("/* Constants from uniconv.h.  */\n");
  pf ("#define SCM_ICONVEH_ERROR %d\n", SCM_I_GSC_ICONVEH_ERROR);
  pf ("#define SCM_ICONVEH_QUESTION_MARK %d\n",
      SCM_I_GSC_ICONVEH_QUESTION_MARK);
  pf ("#define SCM_ICONVEH_ESCAPE_SEQUENCE %d\n",
      SCM_I_GSC_ICONVEH_ESCAPE_SEQUENCE);  

  pf ("\n");
  pf ("/* Define to 1 if there is an auxiliary stack, as in ia64.  */\n");
  pf ("#define SCM_HAVE_AUXILIARY_STACK %d\n", SCM_I_GSC_HAVE_AUXILIARY_STACK);

  pf ("\n");
  pf ("/* Define to 1 to use mini GMP.  */\n");
#if SCM_I_GSC_ENABLE_MINI_GMP == 1
  pf ("#define SCM_ENABLE_MINI_GMP 1\n");
#else
  pf ("#define SCM_ENABLE_MINI_GMP 0\n");
#endif

  printf ("#endif\n");

  return 0;
}