Add libmpdec-dev to CI deps, remove CI hack, and enforce mpdecimal ve…

…rsion check in configure

.github/workflows/build.yml

@@ -232,8 +232,7 @@ jobs:
         ../cpython-ro-srcdir/configure \
           --config-cache \
           --with-pydebug \
-          --with-openssl=$OPENSSL_DIR \
-          --with-system-libmpdec=no
+          --with-openssl=$OPENSSL_DIR
 
   build_ubuntu_free_threading:
     name: 'Ubuntu (free-threading)'
@@ -247,8 +246,7 @@ jobs:
           --config-cache \
           --with-pydebug \
           --with-openssl=$OPENSSL_DIR \
-          --disable-gil \
-          --with-system-libmpdec=no
+          --disable-gil
 
   build_ubuntu_ssltests:
     name: 'Ubuntu SSL tests with OpenSSL'
@@ -373,8 +371,7 @@ jobs:
         ../cpython-ro-srcdir/configure \
           --config-cache \
           --with-pydebug \
-          --with-openssl=$OPENSSL_DIR \
-          --with-system-libmpdec=no
+          --with-openssl=$OPENSSL_DIR
     - name: Build CPython out-of-tree
       working-directory: ${{ env.CPYTHON_BUILDDIR }}
       run: make -j4
@@ -480,7 +477,7 @@ jobs:
         save: ${{ github.event_name == 'push' }}
         max-size: "200M"
     - name: Configure CPython
-      run: ./configure --config-cache --with-address-sanitizer --without-pymalloc --with-system-libmpdec=no
+      run: ./configure --config-cache --with-address-sanitizer --without-pymalloc
     - name: Build CPython
       run: make -j4
     - name: Display build info

.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 \

configure.ac

@@ -3983,7 +3983,7 @@ 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=${LIBMPDEC_LIBS-"-lmpdec -lm"}
      LIBMPDEC_INTERNAL=])],
@@ -3995,9 +3995,17 @@ AS_VAR_IF([with_system_libmpdec], [yes],
   [WITH_SAVE_ENV([
     CPPFLAGS="$LIBMPDEC_CFLAGS $CPPFLAGS"
     LDFLAGS="$LIBMPDEC_LIBS $LDFLAGS"
-    AC_SEARCH_LIBS(
-      [mpd_version], [mpdec],
-      [have_mpdec=yes], [have_mpdec=no])])],
+
+    AC_LINK_IFELSE([
+      AC_LANG_PROGRAM([
+        #include <mpdecimal.h>
+        #if MPD_VERSION_HEX < 0x02050000
+        #  error "mpdecimal 2.5.0 or higher required"
+        #endif
+      ], [void *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;