Re: regex cannot be compiled with g++

[Paul Eggert]

That problem arises because for some reason glibc prefers old-style
function definitions when defining external functions meant to be
called from C code.  Does anyone know why that is?  I assume it's some
API thing.

As for changes like this:

-  dfa->state_table = calloc (sizeof (struct re_state_table_entry), table_size);
+  dfa->state_table = (re_state_table_entry*)
+    calloc (sizeof (struct re_state_table_entry), table_size);

I dunno, it looks to me like a cure that is worse than the disease.
Can't you arrange to compile that function using gcc rather than g++?