Decide whether string-literals must be null-terminated.

[asoffer]

The obvious benefit here is being able to pass a "hello".data to a C API without thinking about it. However, Since the advent of std::string_view in C++ (which is effectively identical to our []char, we see many instances where people access the data pointer incorrectly.

Another option is, if we have compile-time verifiable preconditions, building a "provably null-terminated" precondition on most C APIs.

[perimosocordiae]

+1 for ensuring string literals are null-terminated.

[asoffer]

Closing this as a decision is made. The extra byte seems worth the cost for ease of interacting with C-APIs. We will want strong static analysis determining the presence of null terminator. We'll also want to be careful about specification. For example it can't be illegal to access data through a slice even if that data is not contained inside the slice (because the null terminator won't be).

So it would need to be legal to do something like:

s ::= "hello world"
my_slice := slice(s.data, 5)
my_slice[7] // We don't have to allow this syntax, but we do have to allow access through the slice in this way.

I'm confident we can make this work without too much trouble.