maint: Include Guile's M4 macros.

This ensures 'GUILE_PKG' & co. behaves as we want.  Previously we had
problem in CI when using 'guile.m4' coming from potentially old distro
packages, as discussed in issue !1020:

  https://gitlab.com/gnutls/gnutls/merge_requests/1020#note_194443890

* m4/guile.m4: New file, from Guile's 'stable-2.2' branch,
commit 9846178c69445142ef0b9432417453d2d4de6635.
* .x-sc_prohibit_test_minus_ao: New file.

Signed-off-by: Ludovic Courtès <ludo@gnu.org>

2 files changed, 395 insertions, 0 deletions

diff --git a/.x-sc_prohibit_test_minus_ao b/.x-sc_prohibit_test_minus_ao
new file mode 100644
index 0000000000..ad4342ffed
--- /dev/null
+++ b/.x-sc_prohibit_test_minus_ao
@@ -0,0 +1 @@
+^m4/guile.m4
diff --git a/m4/guile.m4 b/m4/guile.m4
new file mode 100644
index 0000000000..89823e9c38
--- /dev/null
+++ b/m4/guile.m4
@@ -0,0 +1,394 @@
+## Autoconf macros for working with Guile.
+##
+##   Copyright (C) 1998,2001, 2006, 2010, 2012, 2013, 2014 Free Software Foundation, Inc.
+##
+## This library 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.
+##
+## This library 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 this library; if not, write to the Free Software
+## Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+## 02110-1301 USA
+
+# serial 10
+
+## Index
+## -----
+##
+## GUILE_PKG -- find Guile development files
+## GUILE_PROGS -- set paths to Guile interpreter, config and tool programs
+## GUILE_FLAGS -- set flags for compiling and linking with Guile
+## GUILE_SITE_DIR -- find path to Guile "site" directories
+## GUILE_CHECK -- evaluate Guile Scheme code and capture the return value
+## GUILE_MODULE_CHECK -- check feature of a Guile Scheme module
+## GUILE_MODULE_AVAILABLE -- check availability of a Guile Scheme module
+## GUILE_MODULE_REQUIRED -- fail if a Guile Scheme module is unavailable
+## GUILE_MODULE_EXPORTS -- check if a module exports a variable
+## GUILE_MODULE_REQUIRED_EXPORT -- fail if a module doesn't export a variable
+
+## Code
+## ----
+
+## NOTE: Comments preceding an AC_DEFUN (starting from "Usage:") are massaged
+## into doc/ref/autoconf-macros.texi (see Makefile.am in that directory).
+
+# GUILE_PKG -- find Guile development files
+#
+# Usage: GUILE_PKG([VERSIONS])
+#
+# This macro runs the @code{pkg-config} tool to find development files
+# for an available version of Guile.
+#
+# By default, this macro will search for the latest stable version of
+# Guile (e.g. 2.2), falling back to the previous stable version
+# (e.g. 2.0) if it is available.  If no guile-@var{VERSION}.pc file is
+# found, an error is signalled.  The found version is stored in
+# @var{GUILE_EFFECTIVE_VERSION}.
+#
+# If @code{GUILE_PROGS} was already invoked, this macro ensures that the
+# development files have the same effective version as the Guile
+# program.
+#
+# @var{GUILE_EFFECTIVE_VERSION} is marked for substitution, as by
+# @code{AC_SUBST}.
+#
+AC_DEFUN([GUILE_PKG],
+ [PKG_PROG_PKG_CONFIG
+  _guile_versions_to_search="m4_default([$1], [2.2 2.0 1.8])"
+  if test -n "$GUILE_EFFECTIVE_VERSION"; then
+    _guile_tmp=""
+    for v in $_guile_versions_to_search; do
+      if test "$v" = "$GUILE_EFFECTIVE_VERSION"; then
+        _guile_tmp=$v
+      fi
+    done
+    if test -z "$_guile_tmp"; then
+      AC_MSG_FAILURE([searching for guile development files for versions $_guile_versions_to_search, but previously found $GUILE version $GUILE_EFFECTIVE_VERSION])
+    fi
+    _guile_versions_to_search=$GUILE_EFFECTIVE_VERSION
+  fi
+  GUILE_EFFECTIVE_VERSION=""
+  _guile_errors=""
+  for v in $_guile_versions_to_search; do
+    if test -z "$GUILE_EFFECTIVE_VERSION"; then
+      AC_MSG_NOTICE([checking for guile $v])
+      PKG_CHECK_EXISTS([guile-$v], [GUILE_EFFECTIVE_VERSION=$v], [])
+    fi
+  done
+
+  if test -z "$GUILE_EFFECTIVE_VERSION"; then
+    AC_MSG_ERROR([
+No Guile development packages were found.
+
+Please verify that you have Guile installed.  If you installed Guile
+from a binary distribution, please verify that you have also installed
+the development packages.  If you installed it yourself, you might need
+to adjust your PKG_CONFIG_PATH; see the pkg-config man page for more.
+])
+  fi
+  AC_MSG_NOTICE([found guile $GUILE_EFFECTIVE_VERSION])
+  AC_SUBST([GUILE_EFFECTIVE_VERSION])
+ ])
+
+# GUILE_FLAGS -- set flags for compiling and linking with Guile
+#
+# Usage: GUILE_FLAGS
+#
+# This macro runs the @code{pkg-config} tool to find out how to compile
+# and link programs against Guile.  It sets four variables:
+# @var{GUILE_CFLAGS}, @var{GUILE_LDFLAGS}, @var{GUILE_LIBS}, and
+# @var{GUILE_LTLIBS}.
+#
+# @var{GUILE_CFLAGS}: flags to pass to a C or C++ compiler to build code that
+# uses Guile header files.  This is almost always just one or more @code{-I}
+# flags.
+#
+# @var{GUILE_LDFLAGS}: flags to pass to the compiler to link a program
+# against Guile.  This includes @code{-lguile-@var{VERSION}} for the
+# Guile library itself, and may also include one or more @code{-L} flag
+# to tell the compiler where to find the libraries.  But it does not
+# include flags that influence the program's runtime search path for
+# libraries, and will therefore lead to a program that fails to start,
+# unless all necessary libraries are installed in a standard location
+# such as @file{/usr/lib}.
+#
+# @var{GUILE_LIBS} and @var{GUILE_LTLIBS}: flags to pass to the compiler or to
+# libtool, respectively, to link a program against Guile.  It includes flags
+# that augment the program's runtime search path for libraries, so that shared
+# libraries will be found at the location where they were during linking, even
+# in non-standard locations.  @var{GUILE_LIBS} is to be used when linking the
+# program directly with the compiler, whereas @var{GUILE_LTLIBS} is to be used
+# when linking the program is done through libtool.
+#
+# The variables are marked for substitution, as by @code{AC_SUBST}.
+#
+AC_DEFUN([GUILE_FLAGS],
+ [AC_REQUIRE([GUILE_PKG])
+  PKG_CHECK_MODULES(GUILE, [guile-$GUILE_EFFECTIVE_VERSION])
+
+  dnl GUILE_CFLAGS and GUILE_LIBS are already defined and AC_SUBST'd by
+  dnl PKG_CHECK_MODULES.  But GUILE_LIBS to pkg-config is GUILE_LDFLAGS
+  dnl to us.
+
+  GUILE_LDFLAGS=$GUILE_LIBS
+
+  dnl Determine the platform dependent parameters needed to use rpath.
+  dnl AC_LIB_LINKFLAGS_FROM_LIBS is defined in gnulib/m4/lib-link.m4 and needs
+  dnl the file gnulib/build-aux/config.rpath.
+  AC_LIB_LINKFLAGS_FROM_LIBS([GUILE_LIBS], [$GUILE_LDFLAGS], [])
+  GUILE_LIBS="$GUILE_LDFLAGS $GUILE_LIBS"
+  AC_LIB_LINKFLAGS_FROM_LIBS([GUILE_LTLIBS], [$GUILE_LDFLAGS], [yes])
+  GUILE_LTLIBS="$GUILE_LDFLAGS $GUILE_LTLIBS"
+
+  AC_SUBST([GUILE_EFFECTIVE_VERSION])
+  AC_SUBST([GUILE_CFLAGS])
+  AC_SUBST([GUILE_LDFLAGS])
+  AC_SUBST([GUILE_LIBS])
+  AC_SUBST([GUILE_LTLIBS])
+ ])
+
+# GUILE_SITE_DIR -- find path to Guile site directories
+#
+# Usage: GUILE_SITE_DIR
+#
+# This looks for Guile's "site" directories.  The variable @var{GUILE_SITE} will
+# be set to Guile's "site" directory for Scheme source files (usually something
+# like PREFIX/share/guile/site).  @var{GUILE_SITE_CCACHE} will be set to the
+# directory for compiled Scheme files also known as @code{.go} files
+# (usually something like
+# PREFIX/lib/guile/@var{GUILE_EFFECTIVE_VERSION}/site-ccache).
+# @var{GUILE_EXTENSION} will be set to the directory for compiled C extensions
+# (usually something like
+# PREFIX/lib/guile/@var{GUILE_EFFECTIVE_VERSION}/extensions). The latter two
+# are set to blank if the particular version of Guile does not support
+# them.  Note that this macro will run the macros @code{GUILE_PKG} and
+# @code{GUILE_PROGS} if they have not already been run.
+#
+# The variables are marked for substitution, as by @code{AC_SUBST}.
+#
+AC_DEFUN([GUILE_SITE_DIR],
+ [AC_REQUIRE([GUILE_PKG])
+  AC_REQUIRE([GUILE_PROGS])
+  AC_MSG_CHECKING(for Guile site directory)
+  GUILE_SITE=`$PKG_CONFIG --print-errors --variable=sitedir guile-$GUILE_EFFECTIVE_VERSION`
+  AC_MSG_RESULT($GUILE_SITE)
+  if test "$GUILE_SITE" = ""; then
+     AC_MSG_FAILURE(sitedir not found)
+  fi
+  AC_SUBST(GUILE_SITE)
+  AC_MSG_CHECKING([for Guile site-ccache directory using pkgconfig])
+  GUILE_SITE_CCACHE=`$PKG_CONFIG --variable=siteccachedir guile-$GUILE_EFFECTIVE_VERSION`
+  if test "$GUILE_SITE_CCACHE" = ""; then
+    AC_MSG_RESULT(no)
+    AC_MSG_CHECKING([for Guile site-ccache directory using interpreter])
+    GUILE_SITE_CCACHE=`$GUILE -c "(display (if (defined? '%site-ccache-dir) (%site-ccache-dir) \"\"))"`
+    if test $? != "0" -o "$GUILE_SITE_CCACHE" = ""; then
+      AC_MSG_RESULT(no)
+      GUILE_SITE_CCACHE=""
+      AC_MSG_WARN([siteccachedir not found])
+    fi
+  fi
+  AC_MSG_RESULT($GUILE_SITE_CCACHE)
+  AC_SUBST([GUILE_SITE_CCACHE])
+  AC_MSG_CHECKING(for Guile extensions directory)
+  GUILE_EXTENSION=`$PKG_CONFIG --print-errors --variable=extensiondir guile-$GUILE_EFFECTIVE_VERSION`
+  AC_MSG_RESULT($GUILE_EXTENSION)
+  if test "$GUILE_EXTENSION" = ""; then
+    GUILE_EXTENSION=""
+    AC_MSG_WARN(extensiondir not found)
+  fi
+  AC_SUBST(GUILE_EXTENSION)
+ ])
+
+# GUILE_PROGS -- set paths to Guile interpreter, config and tool programs
+#
+# Usage: GUILE_PROGS([VERSION])
+#
+# This macro looks for programs @code{guile} and @code{guild}, setting
+# variables @var{GUILE} and @var{GUILD} to their paths, respectively.
+# The macro will attempt to find @code{guile} with the suffix of
+# @code{-X.Y}, followed by looking for it with the suffix @code{X.Y}, and
+# then fall back to looking for @code{guile} with no suffix. If
+# @code{guile} is still not found, signal an error. The suffix, if any,
+# that was required to find @code{guile} will be used for @code{guild}
+# as well.
+#
+# By default, this macro will search for the latest stable version of
+# Guile (e.g. 2.2). x.y or x.y.z versions can be specified. If an older
+# version is found, the macro will signal an error.
+#
+# The effective version of the found @code{guile} is set to
+# @var{GUILE_EFFECTIVE_VERSION}.  This macro ensures that the effective
+# version is compatible with the result of a previous invocation of
+# @code{GUILE_FLAGS}, if any.
+#
+# As a legacy interface, it also looks for @code{guile-config} and
+# @code{guile-tools}, setting @var{GUILE_CONFIG} and @var{GUILE_TOOLS}.
+#
+# The variables are marked for substitution, as by @code{AC_SUBST}.
+#
+AC_DEFUN([GUILE_PROGS],
+ [_guile_required_version="m4_default([$1], [$GUILE_EFFECTIVE_VERSION])"
+  if test -z "$_guile_required_version"; then
+    _guile_required_version=2.2
+  fi
+
+  _guile_candidates=guile
+  _tmp=
+  for v in `echo "$_guile_required_version" | tr . ' '`; do
+    if test -n "$_tmp"; then _tmp=$_tmp.; fi
+    _tmp=$_tmp$v
+    _guile_candidates="guile-$_tmp guile$_tmp $_guile_candidates"
+  done
+
+  AC_PATH_PROGS(GUILE,[$_guile_candidates])
+  if test -z "$GUILE"; then
+      AC_MSG_ERROR([guile required but not found])
+  fi
+
+  _guile_suffix=`echo "$GUILE" | sed -e 's,^.*/guile\(.*\)$,\1,'`
+  _guile_effective_version=`$GUILE -c "(display (effective-version))"`
+  if test -z "$GUILE_EFFECTIVE_VERSION"; then
+    GUILE_EFFECTIVE_VERSION=$_guile_effective_version
+  elif test "$GUILE_EFFECTIVE_VERSION" != "$_guile_effective_version"; then
+    AC_MSG_ERROR([found development files for Guile $GUILE_EFFECTIVE_VERSION, but $GUILE has effective version $_guile_effective_version])
+  fi
+
+  _guile_major_version=`$GUILE -c "(display (major-version))"`
+  _guile_minor_version=`$GUILE -c "(display (minor-version))"`
+  _guile_micro_version=`$GUILE -c "(display (micro-version))"`
+  _guile_prog_version="$_guile_major_version.$_guile_minor_version.$_guile_micro_version"
+
+  AC_MSG_CHECKING([for Guile version >= $_guile_required_version])
+  _major_version=`echo $_guile_required_version | cut -d . -f 1`
+  _minor_version=`echo $_guile_required_version | cut -d . -f 2`
+  _micro_version=`echo $_guile_required_version | cut -d . -f 3`
+  if test "$_guile_major_version" -gt "$_major_version"; then
+    true
+  elif test "$_guile_major_version" -eq "$_major_version"; then
+    if test "$_guile_minor_version" -gt "$_minor_version"; then
+      true
+    elif test "$_guile_minor_version" -eq "$_minor_version"; then
+      if test -n "$_micro_version"; then
+        if test "$_guile_micro_version" -lt "$_micro_version"; then
+          AC_MSG_ERROR([Guile $_guile_required_version required, but $_guile_prog_version found])
+        fi
+      fi
+    elif test "$GUILE_EFFECTIVE_VERSION" = "$_major_version.$_minor_version" -a -z "$_micro_version"; then
+      # Allow prereleases that have the right effective version.
+      true
+    else
+      as_fn_error $? "Guile $_guile_required_version required, but $_guile_prog_version found" "$LINENO" 5
+    fi
+  elif test "$GUILE_EFFECTIVE_VERSION" = "$_major_version.$_minor_version" -a -z "$_micro_version"; then
+    # Allow prereleases that have the right effective version.
+    true
+  else
+    AC_MSG_ERROR([Guile $_guile_required_version required, but $_guile_prog_version found])
+  fi
+  AC_MSG_RESULT([$_guile_prog_version])
+
+  AC_PATH_PROG(GUILD,[guild$_guile_suffix])
+  AC_SUBST(GUILD)
+
+  AC_PATH_PROG(GUILE_CONFIG,[guile-config$_guile_suffix])
+  AC_SUBST(GUILE_CONFIG)
+  if test -n "$GUILD"; then
+    GUILE_TOOLS=$GUILD
+  else
+    AC_PATH_PROG(GUILE_TOOLS,[guile-tools$_guile_suffix])
+  fi
+  AC_SUBST(GUILE_TOOLS)
+ ])
+
+# GUILE_CHECK -- evaluate Guile Scheme code and capture the return value
+#
+# Usage: GUILE_CHECK_RETVAL(var,check)
+#
+# @var{var} is a shell variable name to be set to the return value.
+# @var{check} is a Guile Scheme expression, evaluated with "$GUILE -c", and
+#    returning either 0 or non-#f to indicate the check passed.
+#    Non-0 number or #f indicates failure.
+#    Avoid using the character "#" since that confuses autoconf.
+#
+AC_DEFUN([GUILE_CHECK],
+ [AC_REQUIRE([GUILE_PROGS])
+  $GUILE -c "$2" > /dev/null 2>&1
+  $1=$?
+ ])
+
+# GUILE_MODULE_CHECK -- check feature of a Guile Scheme module
+#
+# Usage: GUILE_MODULE_CHECK(var,module,featuretest,description)
+#
+# @var{var} is a shell variable name to be set to "yes" or "no".
+# @var{module} is a list of symbols, like: (ice-9 common-list).
+# @var{featuretest} is an expression acceptable to GUILE_CHECK, q.v.
+# @var{description} is a present-tense verb phrase (passed to AC_MSG_CHECKING).
+#
+AC_DEFUN([GUILE_MODULE_CHECK],
+         [AC_MSG_CHECKING([if $2 $4])
+	  GUILE_CHECK($1,(use-modules $2) (exit ((lambda () $3))))
+	  if test "$$1" = "0" ; then $1=yes ; else $1=no ; fi
+          AC_MSG_RESULT($$1)
+         ])
+
+# GUILE_MODULE_AVAILABLE -- check availability of a Guile Scheme module
+#
+# Usage: GUILE_MODULE_AVAILABLE(var,module)
+#
+# @var{var} is a shell variable name to be set to "yes" or "no".
+# @var{module} is a list of symbols, like: (ice-9 common-list).
+#
+AC_DEFUN([GUILE_MODULE_AVAILABLE],
+         [GUILE_MODULE_CHECK($1,$2,0,is available)
+         ])
+
+# GUILE_MODULE_REQUIRED -- fail if a Guile Scheme module is unavailable
+#
+# Usage: GUILE_MODULE_REQUIRED(symlist)
+#
+# @var{symlist} is a list of symbols, WITHOUT surrounding parens,
+# like: ice-9 common-list.
+#
+AC_DEFUN([GUILE_MODULE_REQUIRED],
+         [GUILE_MODULE_AVAILABLE(ac_guile_module_required, ($1))
+          if test "$ac_guile_module_required" = "no" ; then
+              AC_MSG_ERROR([required guile module not found: ($1)])
+          fi
+         ])
+
+# GUILE_MODULE_EXPORTS -- check if a module exports a variable
+#
+# Usage: GUILE_MODULE_EXPORTS(var,module,modvar)
+#
+# @var{var} is a shell variable to be set to "yes" or "no".
+# @var{module} is a list of symbols, like: (ice-9 common-list).
+# @var{modvar} is the Guile Scheme variable to check.
+#
+AC_DEFUN([GUILE_MODULE_EXPORTS],
+ [GUILE_MODULE_CHECK($1,$2,$3,exports `$3')
+ ])
+
+# GUILE_MODULE_REQUIRED_EXPORT -- fail if a module doesn't export a variable
+#
+# Usage: GUILE_MODULE_REQUIRED_EXPORT(module,modvar)
+#
+# @var{module} is a list of symbols, like: (ice-9 common-list).
+# @var{modvar} is the Guile Scheme variable to check.
+#
+AC_DEFUN([GUILE_MODULE_REQUIRED_EXPORT],
+ [GUILE_MODULE_EXPORTS(guile_module_required_export,$1,$2)
+  if test "$guile_module_required_export" = "no" ; then
+      AC_MSG_ERROR([module $1 does not export $2; required])
+  fi
+ ])
+
+## guile.m4 ends here