Allow cast any type to TVoid to just evaluate side-effects

Author: michael-schwarz

src/frontc/cabs2cil.ml

@@ -1416,7 +1416,7 @@ let rec castTo ?(fromsource=false)
         result
 
           (* The expression is evaluated for its side-effects *)
-    | (TInt _ | TEnum _ | TPtr _ ), TVoid _ ->
+    | _ , TVoid _ ->
         (ot, e)
 
           (* Even casts between structs are allowed when we are only

test/small1/c99-tgmath2.c

@@ -10,7 +10,7 @@ typedef struct loc_t
 
 
 void fun(const loc_t* loc) {
-    long l;
+    long l =8;
     int n0 =(int)sqrt(l); // works
     int n1 =(int)sqrt(loc->nloc); // fails
 }
@@ -21,4 +21,5 @@ int main() {
   loc.nloc = 5;
   loc_t* ptr = &loc;
   fun(ptr);
+  SUCCESS;
 }