Add new macro M_SAFE_C

m-core.h

@@ -221,6 +221,15 @@
 #define M_PARENTHESISI_DETECT(...)  0, 1,
 #define M_PARENTHESIS_P(x)          M_RET_ARG2(M_PARENTHESISI_DETECT x, 0, useless)
 
+/* Concat a and b like M_C but
+   do not do it if either a or b is a parenthesis
+   Example: 
+   M_SAFE_C(aaa,bbb) --> aaabbb
+   M_SAFE_C((a), b)  --> (a) b
+*/
+#define M_SAFE_C(a,b)                                                   \
+  M_IF(M_OR(M_PARENTHESIS_P(a), M_PARENTHESIS_P(b)))(a b, M_C(a,b))
+
 /* Necessary macros to handle recursivity */
 /* Delay the evaluation by one level or two or three or ... */
 /* The argument is a macro-function which has to be deferred */