configure: improve MySQL detection, unset USE_MYSQL with failure

configure

@@ -12106,20 +12106,87 @@ if test "x$ac_cv_func_mysql_server_init" = xyes
 then :
 
 else $as_nop
-  MYSQLDLIB="";
-                  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: WARNING: libmysqld not found" >&5
-printf "%s\n" "$as_me: WARNING: libmysqld not found" >&2;}
+  if test "$cross_compiling" = yes
+then :
+  { { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
+printf "%s\n" "$as_me: error: in \`$ac_pwd':" >&2;}
+as_fn_error $? "cannot run test program while cross compiling
+See \`config.log' for more details" "$LINENO" 5; }
+else $as_nop
+
+# ac_fn_cxx_try_run LINENO
+# ------------------------
+# Try to run conftest.$ac_ext, and return whether this succeeded. Assumes that
+# executables *can* be run.
+ac_fn_cxx_try_run ()
+{
+  as_lineno=${as_lineno-"$1"} as_lineno_stack=as_lineno_stack=$as_lineno_stack
+  if { { ac_try="$ac_link"
+case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval ac_try_echo="\"\$as_me:${as_lineno-$LINENO}: $ac_try_echo\""
+printf "%s\n" "$ac_try_echo"; } >&5
+  (eval "$ac_link") 2>&5
+  ac_status=$?
+  printf "%s\n" "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; } && { ac_try='./conftest$ac_exeext'
+  { { case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval ac_try_echo="\"\$as_me:${as_lineno-$LINENO}: $ac_try_echo\""
+printf "%s\n" "$ac_try_echo"; } >&5
+  (eval "$ac_try") 2>&5
+  ac_status=$?
+  printf "%s\n" "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }; }
+then :
+  ac_retval=0
+else $as_nop
+  printf "%s\n" "$as_me: program exited with status $ac_status" >&5
+       printf "%s\n" "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+       ac_retval=$ac_status
 fi
+  rm -rf conftest.dSYM conftest_ipa8_conftest.oo
+  eval $as_lineno_stack; ${as_lineno_stack:+:} unset as_lineno
+  as_fn_set_status $ac_retval
 
-    LIBS=$ac_save_libs
+} # ac_fn_cxx_try_run
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+        #include mysql.h
+        int main(void) {
+        mysql_server_init(0, NULL, NULL);
+        return 0;
+        }
+
+_ACEOF
+if ac_fn_cxx_try_run "$LINENO"
+then :
+
+else $as_nop
+  USE_MYSQL=; MYSQLDLIB=""; { printf "%s\n" "$as_me:${as_lineno-$LINENO}: WARNING: mysql_server_init not found" >&5
+printf "%s\n" "$as_me: WARNING: mysql_server_init not found" >&2;}
+fi
+rm -f core *.core core.conftest.* gmon.out bb.out conftest$ac_exeext \
+  conftest.$ac_objext conftest.beam conftest.$ac_ext
+fi
+
+fi
+
+    LIBS=${ac_save_libs}
     ac_ext=c
 ac_cpp='$CPP $CPPFLAGS'
 ac_compile='$CC -c $CFLAGS $CPPFLAGS conftest.$ac_ext >&5'
 ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
 ac_compiler_gnu=$ac_cv_c_compiler_gnu
 
   fi
-
 fi # $USE_MYSQL
 
 

configure.ac

@@ -1286,12 +1286,17 @@ if test -n "$USE_MYSQL"; then
     MYSQLDLIB=`"$MYSQLD_CONFIG" --libmysqld-libs`
 
     LIBS="$MYSQLDLIB $LIBS"
-    AC_CHECK_FUNC(mysql_server_init,,[MYSQLDLIB="";
-                  AC_MSG_WARN([libmysqld not found])] )
-    LIBS=$ac_save_libs
+    AC_CHECK_FUNC(mysql_server_init,,
+      AC_RUN_IFELSE([AC_LANG_SOURCE([[
+        #include mysql.h
+        int main(void) {
+        mysql_server_init(0, NULL, NULL);
+        return 0;
+        }
+        ]])],,[USE_MYSQL=; MYSQLDLIB=""; AC_MSG_WARN([mysql_server_init not found])]))
+    LIBS=${ac_save_libs}
     AC_LANG_POP([C++])
   fi
-
 fi # $USE_MYSQL
 
 AC_SUBST(USE_MYSQL)