type simplify_concatenation

This improves type safety.

Author: Daniel Kroening

src/util/simplify_expr.cpp

@@ -2244,7 +2244,7 @@ bool simplify_exprt::simplify_node(exprt &expr)
   }
   else if(expr.id()==ID_concatenation)
   {
-    r = simplify_concatenation(expr);
+    r = simplify_concatenation(to_concatenation_expr(expr));
   }
   else if(expr.id()==ID_extractbits)
   {

src/util/simplify_expr_class.h

@@ -34,6 +34,7 @@ class bitnot_exprt;
 class bswap_exprt;
 class byte_extract_exprt;
 class byte_update_exprt;
+class concatenation_exprt;
 class dereference_exprt;
 class div_exprt;
 class exprt;
@@ -136,7 +137,7 @@ class simplify_exprt
   NODISCARD resultt<> simplify_typecast(const typecast_exprt &);
   NODISCARD resultt<> simplify_extractbit(const extractbit_exprt &);
   NODISCARD resultt<> simplify_extractbits(const extractbits_exprt &);
-  NODISCARD resultt<> simplify_concatenation(const exprt &);
+  NODISCARD resultt<> simplify_concatenation(const concatenation_exprt &);
   NODISCARD resultt<> simplify_mult(const mult_exprt &);
   NODISCARD resultt<> simplify_div(const div_exprt &);
   NODISCARD resultt<> simplify_mod(const mod_exprt &);

src/util/simplify_expr_int.cpp

@@ -803,7 +803,7 @@ simplify_exprt::simplify_extractbit(const extractbit_exprt &expr)
 }
 
 simplify_exprt::resultt<>
-simplify_exprt::simplify_concatenation(const exprt &expr)
+simplify_exprt::simplify_concatenation(const concatenation_exprt &expr)
 {
   bool no_change = true;