xxd Code Generation is not compatible with C standard for large arrays

[Kuratius]

Steps to reproduce

The option -i is supposed to generate an array length variable as an int. The C standard only guarantees 16 bits for an int. An array greater than 2^16 entries should cause issues.

Expected behaviour

Generate a type that can hold the maximum array size for a platform, e.g. size_t

Version of Vim

I read the source code on the repo

Environment

Irrelevant

Logs and stack traces

No response

[chrisbra]

PR was reverted in fa8c971

[Kuratius]

From what I understand, the PR was reverted because some projects include the standard headers that have size_t after including the generated code from xxd -i, or don't include them at all, although I still don't know any examples of such projects.

So a solution needs to be implemented when xxd/vim decides to make a breaking change, the header needs to be included, or there needs to be fully dynamic type generation.

I'm not sure if there are examples where using dynamic type generation can still fail, but I suppose this depends on what calculations are done with the array size.

I'm sure it's possible to come up with pathological examples like https://mohitmv.github.io/blog/Shocking-Undefined-Behaviour-In-Action/ example1, but those might not necessarily be things that a normal person would do with an array size variable. It might happen when a type is not promoted appropriately, like if printing the size of an array in bytes whose individual entries are very large, assuming someone doesn't use sizeof() for this.

Implementing dynamic type generation would ideally also fix #13887 .