diff -r 53e22f112b11 -r 15b3ca7ee33f configure
--- a/configure	Tue Nov 12 17:34:04 2024 +0100
+++ b/configure	Mon Nov 18 22:05:42 2024 +0100
@@ -113,6 +113,7 @@
 
 Optional Features:
   --enable-coverage
+  --disable-cxx-tests     the check-cxx makefile target
   --disable-szmul-builtin use custom implementation, instead
 
 __EOF__
@@ -159,6 +160,7 @@
 fi
 
 # features
+FEATURE_CXX_TESTS=auto
 FEATURE_SZMUL_BUILTIN=auto
 
 #
@@ -189,6 +191,8 @@
         "--with-docs="*) OPT_WITH_DOCS=${ARG#--with-docs=} ;;
         "--enable-coverage") FEATURE_COVERAGE=on ;;
         "--disable-coverage") unset FEATURE_COVERAGE ;;
+        "--enable-cxx-tests") FEATURE_CXX_TESTS=on ;;
+        "--disable-cxx-tests") unset FEATURE_CXX_TESTS ;;
         "--enable-szmul-builtin") FEATURE_SZMUL_BUILTIN=on ;;
         "--disable-szmul-builtin") unset FEATURE_SZMUL_BUILTIN ;;
         "-"*) echo "unknown option: $ARG"; abort_configure ;;
@@ -263,6 +267,9 @@
 # check languages
 lang_c=
 lang_cpp=
+if detect_cpp_compiler ; then
+    lang_cpp=1
+fi
 if detect_c_compiler ; then
     lang_c=1
 fi
@@ -335,6 +342,24 @@
     dep_checked_pandoc=1
     return 0
 }
+dependency_error_cxx()
+{
+    print_check_msg "$dep_checked_cxx" "checking for cxx... "
+    # dependency cxx
+    while true
+    do
+        if [ -z "$lang_cpp" ] ; then
+            break
+        fi
+        print_check_msg "$dep_checked_cxx" "yes\n"
+        dep_checked_cxx=1
+        return 1
+    done
+
+    print_check_msg "$dep_checked_cxx" "no\n"
+    dep_checked_cxx=1
+    return 0
+}
 dependency_error_c()
 {
     print_check_msg "$dep_checked_c" "checking for c... "
@@ -612,6 +637,30 @@
 else
     :
 fi
+if [ -n "$FEATURE_CXX_TESTS" ]; then
+    # check dependency
+    if dependency_error_cxx ; then
+        # "auto" features can fail and are just disabled in this case
+        if [ "$FEATURE_CXX_TESTS" = "auto" ]; then
+            DISABLE_FEATURE_CXX_TESTS=1
+        else
+            DEPENDENCIES_FAILED="$DEPENDENCIES_FAILED cxx "
+            ERROR=1
+        fi
+    fi
+    if [ -n "$DISABLE_FEATURE_CXX_TESTS" ]; then
+        unset FEATURE_CXX_TESTS
+    fi
+fi
+if [ -n "$FEATURE_CXX_TESTS" ]; then
+    :
+    cat >> "$TEMP_DIR/make.mk" << __EOF__
+# Enable the check-cxx target
+WITH_CXX_TEST=yes
+__EOF__
+else
+    :
+fi
 if [ -n "$FEATURE_SZMUL_BUILTIN" ]; then
     if [ -n "$DISABLE_FEATURE_SZMUL_BUILTIN" ]; then
         unset FEATURE_SZMUL_BUILTIN
@@ -748,6 +797,11 @@
 else
 echo "  coverage: off"
 fi
+if [ -n "$FEATURE_CXX_TESTS" ]; then
+echo "  cxx-tests: on"
+else
+echo "  cxx-tests: off"
+fi
 if [ -n "$FEATURE_SZMUL_BUILTIN" ]; then
 echo "  szmul-builtin: on"
 else