[m-rev.] for review: add new configuration option for disabling shared libraries

[Julien Fischer]

For review by anyone.

---------------------

Add new configuration option for disabling shared libraries.

configure.ac:
    Add the option --disable-shared-libs, which turns off shared libraries
    even on systems that support them.

    Make the workaround for bug #453 look at the value of the new option,
    rather than that of --disable-dynamic-link.

Julien.

diff --git a/configure.ac b/configure.ac
index 579ad91..460a39c 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1229,14 +1229,14 @@ AC_CHECK_LIB(m, sin, [MATH_LIB=-lm], [MATH_LIB=])

  #-----------------------------------------------------------------------------#
  #
-# Add option for dynamic linking.
+# Check whether the user wants to disable the use of shared libraries.
  #

-AC_ARG_ENABLE(dynamic-link,
-    AC_HELP_STRING([--disable-dynamic-link],
-                   [disable the use of dynamic linking]),
-    [mercury_cv_enable_dynamic_link="$enableval"],
-    [mercury_cv_enable_dynamic_link=yes])
+AC_ARG_ENABLE(shared-libs,
+    AC_HELP_STRING([--disable-shared-libs],
+      [do not build shared version of the library even if that is supported]),
+    [mercury_cv_enable_shared_libs="$enableval"],
+    [mercury_cv_enable_shared_libs=yes])

  #-----------------------------------------------------------------------------#
  #
@@ -2619,7 +2619,7 @@ case "$ac_cv_prog_gcc" in yes)

              # An old hack allowing non-local gotos to work with PIC on x86
              # will no longer work with GCC 5+ (see mercury_goto.h).
-            # The following disables non-local gotos if dynamically linking
+            # The following disables non-local gotos if dynamic linking
              # is enabled, even though statically linked libraries (non-PIC)
              # would still work.
              # Alternatively, we may wish to consider using non-PIC in shared
@@ -2632,7 +2632,7 @@ case "$ac_cv_prog_gcc" in yes)
              case $C_COMPILER_TYPE in
                  gcc_3_*|gcc_4_*) ;;
                  gcc_*)
-                    if test "$mercury_cv_enable_dynamic_link" = yes
+                    if test "$mercury_cv_enable_shared_libs" = yes
                      then
                          mercury_cv_asm_labels=no
                          mercury_cv_gcc_labels=no
@@ -4400,7 +4400,8 @@ ALLOW_UNDEFINED=""
  ERROR_UNDEFINED=""
  DEFAULT_LINKAGE="shared"

-case "$host" in
+if test "$mercury_cv_enable_shared_libs" = "yes"; then
+    case "$host" in
          i*86-*-linux|i*86-*-linux-gnu|x86_64-*-linux*)
              case $ac_cv_prog_gcc in
                  yes)
@@ -4609,7 +4610,16 @@ case "$host" in
              DEFAULT_LINKAGE=static
              AC_MSG_RESULT(no)
              ;;
-esac
+    esac
+else
+    # CFLAGS_FOR_PIC is used by boehm_gc/Makefile when creating libgc.a.
+    # If the system doesn't support shared libraries,
+    # then we should set it to empty, not `-fpic'.
+    CFLAGS_FOR_PIC=
+    EXT_FOR_PIC_OBJECTS=o
+    DEFAULT_LINKAGE=static
+    AC_MSG_RESULT(no)
+fi

  #-----------------------------------------------------------------------------#
  #
@@ -5211,9 +5221,13 @@ AC_SUBST(NSL_LIBRARY)
  #
  # Check libraries for dynamic linking.
  #
-# XXX This needs to occur after mercury_check_for_functions is defined,
-# but the option defining mercury_cv_enable_dynamic_link is needed earlier.
-#
+
+# XXX this is poorly named.
+AC_ARG_ENABLE(dynamic-link,
+    AC_HELP_STRING([--disable-dynamic-link],
+                   [disable the use of dynamic linking]),
+    [mercury_cv_enable_dynamic_link="$enableval"],
+    [mercury_cv_enable_dynamic_link=yes])

  if test "$mercury_cv_enable_dynamic_link" = "yes"; then
      MERCURY_CHECK_FOR_HEADERS(dlfcn.h)