Avoid warning about not returning a value

Author: tautschnig

src/util/byte_operators.cpp

@@ -24,8 +24,11 @@ irep_idt byte_extract_id()
     return ID_byte_extract_big_endian;
 
   case configt::ansi_ct::endiannesst::NO_ENDIANNESS:
-    UNREACHABLE;
+    break;
   }
+
+  UNREACHABLE;
+  return ID_nil;
 }
 
 irep_idt byte_update_id()
@@ -39,6 +42,9 @@ irep_idt byte_update_id()
     return ID_byte_update_big_endian;
 
   case configt::ansi_ct::endiannesst::NO_ENDIANNESS:
-    UNREACHABLE;
+    break;
   }
+
+  UNREACHABLE;
+  return ID_nil;
 }

src/util/c_types.cpp

@@ -68,7 +68,10 @@ unsignedbv_typet size_type()
   else if(config.ansi_c.pointer_width==config.ansi_c.long_long_int_width)
     return unsigned_long_long_int_type();
   else
+  {
     INVARIANT(false, "width of size type"); // aaah!
+    return unsignedbv_typet(0);
+  }
 }
 
 signedbv_typet signed_size_type()
@@ -237,7 +240,10 @@ signedbv_typet pointer_diff_type()
   else if(config.ansi_c.pointer_width==config.ansi_c.long_long_int_width)
     return signed_long_long_int_type();
   else
+  {
     INVARIANT(false, "width of pointer difference");
+    return signedbv_typet(0);
+  }
 }
 
 pointer_typet pointer_type(const typet &subtype)