[whytevuhuni]

Ah, okay. In that case I feel like the only sane way to approach this is to completely abolish null-terminated strings, and reimplement everything (including stuff like printf's format and arguments) in terms of strv. Otherwise if there has to be a 2cstr function, it should be an allocating one.

[uecker]

Reimplementing everything is not an option in C. But one should be able to pass string views directly to printf.

The allocating version is what string_dup does. strv2cstr is certainly more dangerous. But as since the size is encoded in the return type, compilers can add bounds checking (and partially already do so).