generate constraints differently to avoid warnings
diff --git a/tests/tests-asn1c-compiler/137-oer-string-OK.asn1.-Pgen-OER b/tests/tests-asn1c-compiler/137-oer-string-OK.asn1.-Pgen-OER
index bf21904..0f75e76 100644
--- a/tests/tests-asn1c-compiler/137-oer-string-OK.asn1.-Pgen-OER
+++ b/tests/tests-asn1c-compiler/137-oer-string-OK.asn1.-Pgen-OER
@@ -61,7 +61,7 @@
 				| (ch[1] << 16)
 				| (ch[2] << 8)
 				|  ch[3];
-		if(!(1 /* Constraint matches natural range of cv */)) return -1;
+		(void)cv; /* Unused variable */
 	}
 	return 0;
 }