create distinct interned string type

Interned strings are used pervasively, so it's a good idea to add a
layer of type safety to differentiate them from general cstrs and avoid
potential bugs from comparing non-interned and interned strings. Not
that that's happened so far that I can remember, but it could.

I'm 90% sure it's legal to alias `struct {char c;}` pointers with `char`
pointers. This specific typedef gives type safety but with a simple
one-way `internstr -> const char *` typecast (with `&istr->c`).
Converting the other way around is more intentional: a straight up cast
`(internstr)cstr` which sticks out as unchecked and probably wrong, or
calling the intern(cstr) function, which is the right way.

1 files changed, 2 insertions, 2 deletions

diff --git a/c/c.h b/c/c.h
index a19542b..9000496 100644
--- a/c/c.h
+++ b/c/c.h
@@ -92,9 +92,9 @@ struct decl {
          isdef : 1,
          isbuiltin : 1;
    struct span span;
-   const char *name;
+   internstr name;
    union {
-      const char *sym;
+      internstr sym;
       struct { ushort align; int id; };
       vlong value;
       const struct builtin *builtin;