build: Build and check (ice-9 popen) only when --enable-posix and HAVE_FORK.

Fixes <http://bugs.gnu.org/13848>.
Reported by Jan Schukat <shookie@email.de>.

* configure.ac: Rename `HAVE_FORK' conditional to `BUILD_ICE_9_POPEN'.
  Set it when both $enable_posix and $ac_cv_func_fork are true.
* libguile/posix.c (scm_init_posix): Add the `fork' feature.
* doc/ref/api-options.texi (Common Feature Symbols): Add `fork'.
* doc/ref/posix.texi (Pipes): Add footnote mentioning the `fork'
  feature.
* module/Makefile.am (SCRIPTS_SOURCES): Make `scripts/autofrisk.scm' and
  `scripts/scan-api.scm' conditional on `BUILD_ICE_9_POPEN'.
* test-suite/tests/popen.test (if-supported): New macro.
  Wrap body in `if-supported'.

configure.ac

@@ -761,7 +761,8 @@ AC_CHECK_FUNCS([DINFINITY DQNAN cexp chsize clog clog10 ctermid		\
   strcoll strcoll_l newlocale utimensat sched_getaffinity		\
   sched_setaffinity sendfile])
 
-AM_CONDITIONAL([HAVE_FORK], [test "x$ac_cv_func_fork" = "xyes"])
+AM_CONDITIONAL([BUILD_ICE_9_POPEN],
+  [test "x$enable_posix" = "xyes" && test "x$ac_cv_func_fork" = "xyes"])
 
 # Reasons for testing:
 #   netdb.h - not in mingw

doc/ref/api-options.texi

@@ -1,6 +1,7 @@
 @c -*-texinfo-*-
 @c This is part of the GNU Guile Reference Manual.
-@c Copyright (C)  1996, 1997, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2008, 2009, 2010, 2011, 2012
+@c Copyright (C)  1996, 1997, 2000, 2001, 2002, 2003, 2004, 2005, 2006,
+@c   2008, 2009, 2010, 2011, 2012, 2013
 @c   Free Software Foundation, Inc.
 @c See the file guile.texi for copying conditions.
 
@@ -281,6 +282,11 @@ Databases}).
 Indicates support for POSIX functions: @code{pipe}, @code{getgroups},
 @code{kill}, @code{execl} and so on (@pxref{POSIX}).
 
+@item fork
+Indicates support for the POSIX @code{fork} function (@pxref{Processes,
+@code{primitive-fork}}).  This is a prerequisite for the @code{(ice-9
+popen)} module (@pxref{Pipes}).
+
 @item random
 Indicates availability of random number generation functions:
 @code{random}, @code{copy-random-state}, @code{random-uniform} and so on

doc/ref/posix.texi

@@ -2188,7 +2188,8 @@ controlling terminal.  The return value is unspecified.
 
 The following procedures are similar to the @code{popen} and
 @code{pclose} system routines.  The code is in a separate ``popen''
-module:
+module@footnote{This module is only available on systems where the
+@code{fork} feature is provided (@pxref{Common Feature Symbols}).}:
 
 @lisp
 (use-modules (ice-9 popen))

libguile/posix.c

@@ -2336,6 +2336,7 @@ scm_init_posix ()
 #include "libguile/posix.x"
 
 #ifdef HAVE_FORK
+  scm_add_feature ("fork");
   scm_c_register_extension ("libguile-" SCM_EFFECTIVE_VERSION,
                             "scm_init_popen",
 			    (scm_t_extension_init_func) scm_init_popen,

module/Makefile.am

@@ -159,7 +159,6 @@ BRAINFUCK_LANG_SOURCES =			\
   language/brainfuck/spec.scm
 
 SCRIPTS_SOURCES =				\
-  scripts/autofrisk.scm				\
   scripts/compile.scm				\
   scripts/disassemble.scm			\
   scripts/display-commentary.scm		\
@@ -175,7 +174,6 @@ SCRIPTS_SOURCES =				\
   scripts/use2dot.scm				\
   scripts/snarf-check-and-output-texi.scm	\
   scripts/summarize-guile-TODO.scm		\
-  scripts/scan-api.scm				\
   scripts/api-diff.scm				\
   scripts/read-rfc822.scm			\
   scripts/snarf-guile-m4-docs.scm
@@ -252,12 +250,17 @@ ICE_9_SOURCES = \
   ice-9/serialize.scm \
   ice-9/local-eval.scm
 
-if HAVE_FORK
+if BUILD_ICE_9_POPEN
 
 # This functionality is missing on systems without `fork'---i.e., Windows.
 ICE_9_SOURCES += ice-9/popen.scm
 
-endif HAVE_FORK
+# These modules rely on (ice-9 popen).
+SCRIPTS_SOURCES +=				\
+  scripts/autofrisk.scm				\
+  scripts/scan-api.scm
+
+endif BUILD_ICE_9_POPEN
 
 SRFI_SOURCES = \
   srfi/srfi-2.scm \

test-suite/tests/popen.test

@@ -1,6 +1,6 @@
 ;;;; popen.test --- exercise ice-9/popen.scm      -*- scheme -*-
 ;;;;
-;;;; Copyright 2003, 2006, 2010, 2011 Free Software Foundation, Inc.
+;;;; Copyright 2003, 2006, 2010, 2011, 2013 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
@@ -17,9 +17,7 @@
 ;;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 
 (define-module (test-suite test-ice-9-popen)
-  #:use-module (test-suite lib)
-  #:use-module (ice-9 popen))
-
+  #:use-module (test-suite lib))
 
 ;; read from PORT until eof is reached, return what's read as a string
 (define (read-string-to-eof port)
@@ -37,6 +35,13 @@
       thunk
       restore-signals))
 
+(define-syntax-rule (if-supported body ...)
+  (if (provided? 'fork)
+      (begin body ...)))
+
+(if-supported
+ (use-modules (ice-9 popen))
+
 
  ;;
  ;; open-input-pipe
@@ -110,9 +115,7 @@
          (display "hello!\n" (cdr p2c))
          (force-output (cdr p2c))
          (close-pipe port)
-	result)))
-
-  )
+         result))))
 
  ;;
  ;; open-output-pipe
@@ -187,9 +190,7 @@
             ;; the child a broken pipe and so allow it to exit.
             (close-port (car c2p))
             (close-pipe port)
-	   result)))))
-
-  )
+            result))))))
 
  ;;
  ;; close-pipe
@@ -208,5 +209,4 @@
    (pass-if "exit 1"
      (let ((st (close-pipe (open-output-pipe "exit 1"))))
        (and (status:exit-val st)
-	   (= 1 (status:exit-val st))))))
-
+            (= 1 (status:exit-val st)))))))