See the environment variable and then check if JIT options conflict

ruby.c

@@ -1811,11 +1811,6 @@ process_options(int argc, char **argv, ruby_cmdline_options_t *opt)
          */
         rb_warning("-K is specified; it is for 1.8 compatibility and may cause odd behavior");
 
-    if (MULTI_BITS_P(FEATURE_SET_BITS(opt->features) & feature_jit_mask)) {
-        rb_warn("MJIT and YJIT cannot both be enabled at the same time. Exiting");
-        return Qfalse;
-    }
-
     if (!(FEATURE_SET_BITS(opt->features) & feature_jit_mask)) {
 #if YJIT_BUILD
         if (!FEATURE_USED_P(opt->features, yjit) && getenv("RUBY_YJIT_ENABLE")) {
@@ -1823,6 +1818,11 @@ process_options(int argc, char **argv, ruby_cmdline_options_t *opt)
         }
 #endif
     }
+    if (MULTI_BITS_P(FEATURE_SET_BITS(opt->features) & feature_jit_mask)) {
+        rb_warn("MJIT and YJIT cannot both be enabled at the same time. Exiting");
+        return Qfalse;
+    }
+
 #if USE_MJIT
     if (FEATURE_SET_P(opt->features, mjit)) {
         opt->mjit.on = TRUE; /* set mjit.on for ruby_show_version() API and check to call mjit_init() */