Support number##identifier token pasting. Example:

#define K_DOUBLE(x) x##l
K_DOUBLE(0.5)

src/fcpp.c

@@ -940,7 +940,7 @@ void Putstring(struct Global *, char *);
 void Putint(struct Global *, int);
 char *savestring(struct Global *, char *);
 ReturnCode addfile(struct Global *, FILE *, char *);
-int catenate(struct Global *, ReturnCode *);
+int catenate(struct Global *, int lhs_number, ReturnCode *);
 void cerror(struct Global *, ErrorCode, ...);
 ReturnCode control(struct Global *, int *);
 ReturnCode dodefine(struct Global *);
@@ -1265,7 +1265,7 @@ ReturnCode cppmain(struct Global *global)
 	}
 	if((ret=macroid(global, &c)))   /* Grab the token       */
 	  return(ret);
-      } while (type[c] == LET && catenate(global, &ret) && !ret);
+      } while (type[c] == LET && catenate(global, 0, &ret) && !ret);
       if(ret)
 	/* If the loop was broken because of a fatal error! */
 	return(ret);
@@ -1291,6 +1291,9 @@ ReturnCode cppmain(struct Global *global)
 	ret=scannumber(global, c, (ReturnCode(*)(struct Global *, int))output);
 	if(ret)
 	  return(ret);
+	catenate(gloabl, 1, &ret);  /* Check to see if the number is the lhs of a macro concat */
+	if (ret)
+	  return(ret);
 	break;
       case QUO:                 /* char or string const */
 	go = 0;
@@ -3691,7 +3694,7 @@ ReturnCode evallex(struct Global *global,
 	*op=OP_EOE;           /* End of expression    */
 	return(FPP_OK);
       }
-    } while ((t = type[c]) == LET && catenate(global, &ret) && !ret);
+    } while ((t = type[c]) == LET && catenate(global, 0, &ret) && !ret);
     if(ret)
       /* If the loop was broken because of a fatal error! */
       return(ret);
@@ -3852,7 +3855,7 @@ ReturnCode dosizeof(struct Global *global, int *result)
     }
     else if (type[c] != LET)            /* Exit if not a type   */
       break;
-    else if (!catenate(global, &ret) && !ret) { /* Maybe combine tokens */
+    else if (!catenate(global, 0, &ret) && !ret) { /* Maybe combine tokens */
       /*
        * Look for this unexpandable token in basic_types.
        * The code accepts "int long" as well as "long int"
@@ -4368,7 +4371,7 @@ ReturnCode macroid(struct Global *global, int *c)
   return(FPP_OK);
 }
 
-int catenate(struct Global *global, ReturnCode *ret)
+int catenate(struct Global *global, int lhs_number, ReturnCode *ret)
 {
   /*
    * A token was just read (via macroid).
@@ -4380,7 +4383,7 @@ int catenate(struct Global *global, ReturnCode *ret)
 
 #if OK_CONCAT
   int c;
-  char *token1;
+  char *token1 = "";
 #endif
 
 #if OK_CONCAT
@@ -4389,7 +4392,8 @@ int catenate(struct Global *global, ReturnCode *ret)
     return (FALSE);
   }
   else {
-    token1 = savestring(global, global->tokenbuf); /* Save first token     */
+    if (lhs_number == 0)                             /* The lhs number has already been emit */
+      token1 = savestring(global, global->tokenbuf); /* Save first token     */
     c=get(global);
     if(global->rightconcat) {
       *ret=macroid(global, &c);           /* Scan next token      */
@@ -4432,7 +4436,8 @@ int catenate(struct Global *global, ReturnCode *ret)
      * new (concatenated) token after freeing token1.
      * Finally, setup to read the new token.
      */
-    free(token1);                            /* Free up memory       */
+    if (lhs_number == 0)
+      free(token1);                            /* Free up memory       */
     *ret=ungetstring(global, global->work);  /* Unget the new thing, */
     if(*ret)
       return(FALSE);