gh-115119: Default to --with-system-libmpdec=yes (#118539)

Co-authored-by: Zachary Ware <zachary.ware@gmail.com>

.github/workflows/posix-deps-apt.sh

@@ -15,6 +15,7 @@ apt-get -yq install \
     libgdbm-dev \
     libgdbm-compat-dev \
     liblzma-dev \
+    libmpdec-dev \
     libncurses5-dev \
     libreadline6-dev \
     libsqlite3-dev \

Doc/using/configure.rst

@@ -804,11 +804,18 @@ Libraries options
 
 .. option:: --with-system-libmpdec
 
-   Build the ``_decimal`` extension module using an installed ``mpdec``
+   Build the ``_decimal`` extension module using an installed ``mpdecimal``
-   library, see the :mod:`decimal` module (default is no).
+   library, see the :mod:`decimal` module (default is yes).
 
    .. versionadded:: 3.3
 
+   .. versionchanged:: 3.13
+      Default to using the installed ``mpdecimal`` library.
+
+   .. deprecated-removed:: 3.13 3.15
+      A copy of the ``mpdecimal`` library sources will no longer be distributed
+      with Python 3.15.
+
    .. seealso:: :option:`LIBMPDEC_CFLAGS` and :option:`LIBMPDEC_LIBS`.
 
 .. option:: --with-readline=readline|editline

Doc/whatsnew/3.13.rst

@@ -1807,6 +1807,10 @@ Changes in the Python API
 Build Changes
 =============
 
+* The :file:`configure` option :option:`--with-system-libmpdec` now defaults
+  to ``yes``. The bundled copy of ``libmpdecimal`` will be removed in Python
+  3.15.
+
 * Autoconf 2.71 and aclocal 1.16.4 are now required to regenerate
   the :file:`configure` script.
   (Contributed by Christian Heimes in :gh:`89886`.)
@@ -2336,6 +2340,7 @@ Pending Removal in Python 3.14
 Pending Removal in Python 3.15
 ------------------------------
 
+* The bundled copy of ``libmpdecimal``.
 * :c:func:`PyImport_ImportModuleNoBlock`: use :c:func:`PyImport_ImportModule`.
 * :c:func:`PyWeakref_GET_OBJECT`: use :c:func:`PyWeakref_GetRef` instead.
 * :c:func:`PyWeakref_GetObject`: use :c:func:`PyWeakref_GetRef` instead.

Misc/NEWS.d/next/Build/2024-05-06-00-39-06.gh-issue-115119.LT27pF.rst

@@ -0,0 +1,2 @@
+The :file:`configure` option :option:`--with-system-libmpdec` now defaults to ``yes``.
+The bundled copy of ``libmpdecimal`` will be removed in Python 3.15.

configure

@@ -1892,8 +1892,9 @@ Optional Packages:
   --with-libs='lib1 ...'  link against additional libs (default is no)
   --with-system-expat     build pyexpat module using an installed expat
                           library, see Doc/library/pyexpat.rst (default is no)
-  --with-system-libmpdec  build _decimal module using an installed libmpdec
+  --with-system-libmpdec  build _decimal module using an installed mpdecimal
-                          library, see Doc/library/decimal.rst (default is no)
+                          library, see Doc/library/decimal.rst (default is
+                          yes)
   --with-decimal-contextvar
                           build _decimal module using a coroutine-local rather
                           than a thread-local context (default is yes)
@@ -14611,7 +14612,7 @@ if test ${with_system_libmpdec+y}
 then :
   withval=$with_system_libmpdec;
 else $as_nop
-  with_system_libmpdec="no"
+  with_system_libmpdec="yes"
 fi
 
 { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $with_system_libmpdec" >&5
@@ -14621,19 +14622,19 @@ if test "x$with_system_libmpdec" = xyes
 then :
 
 pkg_failed=no
-{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for libmpdec" >&5
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for libmpdec >= 2.5.0" >&5
-printf %s "checking for libmpdec... " >&6; }
+printf %s "checking for libmpdec >= 2.5.0... " >&6; }
 
 if test -n "$LIBMPDEC_CFLAGS"; then
     pkg_cv_LIBMPDEC_CFLAGS="$LIBMPDEC_CFLAGS"
  elif test -n "$PKG_CONFIG"; then
     if test -n "$PKG_CONFIG" && \
-    { { printf "%s\n" "$as_me:${as_lineno-$LINENO}: \$PKG_CONFIG --exists --print-errors \"libmpdec\""; } >&5
+    { { printf "%s\n" "$as_me:${as_lineno-$LINENO}: \$PKG_CONFIG --exists --print-errors \"libmpdec >= 2.5.0\""; } >&5
-  ($PKG_CONFIG --exists --print-errors "libmpdec") 2>&5
+  ($PKG_CONFIG --exists --print-errors "libmpdec >= 2.5.0") 2>&5
   ac_status=$?
   printf "%s\n" "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
   test $ac_status = 0; }; then
-  pkg_cv_LIBMPDEC_CFLAGS=`$PKG_CONFIG --cflags "libmpdec" 2>/dev/null`
+  pkg_cv_LIBMPDEC_CFLAGS=`$PKG_CONFIG --cflags "libmpdec >= 2.5.0" 2>/dev/null`
 		      test "x$?" != "x0" && pkg_failed=yes
 else
   pkg_failed=yes
@@ -14645,12 +14646,12 @@ if test -n "$LIBMPDEC_LIBS"; then
     pkg_cv_LIBMPDEC_LIBS="$LIBMPDEC_LIBS"
  elif test -n "$PKG_CONFIG"; then
     if test -n "$PKG_CONFIG" && \
-    { { printf "%s\n" "$as_me:${as_lineno-$LINENO}: \$PKG_CONFIG --exists --print-errors \"libmpdec\""; } >&5
+    { { printf "%s\n" "$as_me:${as_lineno-$LINENO}: \$PKG_CONFIG --exists --print-errors \"libmpdec >= 2.5.0\""; } >&5
-  ($PKG_CONFIG --exists --print-errors "libmpdec") 2>&5
+  ($PKG_CONFIG --exists --print-errors "libmpdec >= 2.5.0") 2>&5
   ac_status=$?
   printf "%s\n" "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
   test $ac_status = 0; }; then
-  pkg_cv_LIBMPDEC_LIBS=`$PKG_CONFIG --libs "libmpdec" 2>/dev/null`
+  pkg_cv_LIBMPDEC_LIBS=`$PKG_CONFIG --libs "libmpdec >= 2.5.0" 2>/dev/null`
 		      test "x$?" != "x0" && pkg_failed=yes
 else
   pkg_failed=yes
@@ -14671,9 +14672,9 @@ else
         _pkg_short_errors_supported=no
 fi
         if test $_pkg_short_errors_supported = yes; then
-	        LIBMPDEC_PKG_ERRORS=`$PKG_CONFIG --short-errors --print-errors --cflags --libs "libmpdec" 2>&1`
+	        LIBMPDEC_PKG_ERRORS=`$PKG_CONFIG --short-errors --print-errors --cflags --libs "libmpdec >= 2.5.0" 2>&1`
         else
-	        LIBMPDEC_PKG_ERRORS=`$PKG_CONFIG --print-errors --cflags --libs "libmpdec" 2>&1`
+	        LIBMPDEC_PKG_ERRORS=`$PKG_CONFIG --print-errors --cflags --libs "libmpdec >= 2.5.0" 2>&1`
         fi
 	# Put the nasty error message in config.log where it belongs
 	echo "$LIBMPDEC_PKG_ERRORS" >&5
@@ -14700,6 +14701,61 @@ else $as_nop
    LIBMPDEC_INTERNAL="\$(LIBMPDEC_HEADERS) \$(LIBMPDEC_A)"
 fi
 
+if test "x$with_system_libmpdec" = xyes
+then :
+  save_CFLAGS=$CFLAGS
+save_CPPFLAGS=$CPPFLAGS
+save_LDFLAGS=$LDFLAGS
+save_LIBS=$LIBS
+
+
+    CPPFLAGS="$LIBMPDEC_CFLAGS $CPPFLAGS"
+    LIBS="$LIBMPDEC_LIBS $LIBS"
+
+    cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+
+        #include <mpdecimal.h>
+        #if MPD_VERSION_HEX < 0x02050000
+        #  error "mpdecimal 2.5.0 or higher required"
+        #endif
+
+int
+main (void)
+{
+const char *x = mpd_version();
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"
+then :
+  have_mpdec=yes
+else $as_nop
+  have_mpdec=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.beam \
+    conftest$ac_exeext conftest.$ac_ext
+
+CFLAGS=$save_CFLAGS
+CPPFLAGS=$save_CPPFLAGS
+LDFLAGS=$save_LDFLAGS
+LIBS=$save_LIBS
+
+
+else $as_nop
+  have_mpdec=yes
+   { printf "%s\n" "$as_me:${as_lineno-$LINENO}: WARNING: the bundled copy of libmpdecimal is scheduled for removal in Python 3.15; consider using a system installed mpdecimal library." >&5
+printf "%s\n" "$as_me: WARNING: the bundled copy of libmpdecimal is scheduled for removal in Python 3.15; consider using a system installed mpdecimal library." >&2;}
+fi
+
+if test "$with_system_libmpdec" = "yes" && test "$have_mpdec" = "no"
+then :
+  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: WARNING: no system libmpdecimal found; unable to build _decimal" >&5
+printf "%s\n" "$as_me: WARNING: no system libmpdecimal found; unable to build _decimal" >&2;}
+fi
+
 # Disable forced inlining in debug builds, see GH-94847
 if test "x$with_pydebug" = xyes
 then :
@@ -30426,7 +30482,7 @@ then :
 
     if true
 then :
-  if true
+  if test "$have_mpdec" = "yes"
 then :
   py_cv_module__decimal=yes
 else $as_nop

configure.ac

@@ -3974,16 +3974,16 @@ AC_ARG_WITH(
   [system_libmpdec],
   [AS_HELP_STRING(
     [--with-system-libmpdec],
-    [build _decimal module using an installed libmpdec library, see Doc/library/decimal.rst (default is no)]
+    [build _decimal module using an installed mpdecimal library, see Doc/library/decimal.rst (default is yes)]
   )],
   [],
-  [with_system_libmpdec="no"])
+  [with_system_libmpdec="yes"])
 AC_MSG_RESULT([$with_system_libmpdec])
 
 AS_VAR_IF(
   [with_system_libmpdec], [yes],
   [PKG_CHECK_MODULES(
-    [LIBMPDEC], [libmpdec], [],
+    [LIBMPDEC], [libmpdec >= 2.5.0], [],
     [LIBMPDEC_CFLAGS=${LIBMPDEC_CFLAGS-""}
      LIBMPDEC_LIBS=${LIBMPDEC_LIBS-"-lmpdec -lm"}
      LIBMPDEC_INTERNAL=])],
@@ -3991,6 +3991,29 @@ AS_VAR_IF(
    LIBMPDEC_LIBS="-lm \$(LIBMPDEC_A)"
    LIBMPDEC_INTERNAL="\$(LIBMPDEC_HEADERS) \$(LIBMPDEC_A)"])
 
+AS_VAR_IF([with_system_libmpdec], [yes],
+  [WITH_SAVE_ENV([
+    CPPFLAGS="$LIBMPDEC_CFLAGS $CPPFLAGS"
+    LIBS="$LIBMPDEC_LIBS $LIBS"
+
+    AC_LINK_IFELSE([
+      AC_LANG_PROGRAM([
+        #include <mpdecimal.h>
+        #if MPD_VERSION_HEX < 0x02050000
+        #  error "mpdecimal 2.5.0 or higher required"
+        #endif
+      ], [const char *x = mpd_version();])],
+      [have_mpdec=yes],
+      [have_mpdec=no])
+  ])],
+  [AS_VAR_SET([have_mpdec], [yes])
+   AC_MSG_WARN([m4_normalize([
+     the bundled copy of libmpdecimal is scheduled for removal in Python 3.15;
+     consider using a system installed mpdecimal library.])])])
+
+AS_IF([test "$with_system_libmpdec" = "yes" && test "$have_mpdec" = "no"],
+      [AC_MSG_WARN([no system libmpdecimal found; unable to build _decimal])])
+
 # Disable forced inlining in debug builds, see GH-94847
 AS_VAR_IF(
   [with_pydebug], [yes],
@@ -7668,7 +7691,9 @@ PY_STDLIB_MOD([_curses_panel],
   [], [test "$have_panel" != "no"],
   [$PANEL_CFLAGS $CURSES_CFLAGS], [$PANEL_LIBS $CURSES_LIBS]
 )
-PY_STDLIB_MOD([_decimal], [], [], [$LIBMPDEC_CFLAGS], [$LIBMPDEC_LIBS])
+PY_STDLIB_MOD([_decimal],
+  [], [test "$have_mpdec" = "yes"],
+  [$LIBMPDEC_CFLAGS], [$LIBMPDEC_LIBS])
 PY_STDLIB_MOD([_dbm],
   [test -n "$with_dbmliborder"], [test "$have_dbm" != "no"],
   [$DBM_CFLAGS], [$DBM_LIBS])