Enable vsnprintf on compilers newer than 1.73.0.1

[bugadani]

A not terribly complex patch to resolve #16. It might be easier to just bump MSRV, but 🤷‍♂️.

Also closes esp-rs/esp-mbedtls#13

[AnthonyGrondin]

This seems to fix the Xtensa part of esp-rs/esp-mbedtls#13

I haven't narrowed down the problem caused by printing \n, for RISCV targets (now Xtensa) after this patch.
I can provide more testing later (24h-48h) with esp-mbedtls if needed.

I'd like to get it fixed eventually so that I don't have to patch every printf in mbedtls C libs because they're not printing 😆

[bugadani]

Hmm, do you have access to something I don't? This PR should have no effect right now without the yet-to-be-built compiler 😅 But I'll take a win if you offer one.

As to \n, if the problem is now consistent between xtensa and risc-v, maybe we can go through the vsnprintf algo to see what's what.

[AnthonyGrondin]

Oh, no I don't.

I didn't realize it wasn't out yet. I just did a static analysis.

[bjoernQ]

You can already download builds for Windows MSVC and Linux 64:
https://github.com/esp-rs/rust-build/releases/tag/untagged-3ecdd54e672f465cad2e

[bjoernQ]

Should also conditionally enable calling syslog in log_write and log_writev

[bugadani]

You can already download builds for Windows MSVC and Linux 64: https://github.com/esp-rs/rust-build/releases/tag/untagged-3ecdd54e672f465cad2e

I guess that might be a private pre-release because I'm getting a page not found error.

Should also conditionally enable calling syslog in log_write and log_writev

I think I can just call syslog unconditionally, it should handle the conditional aspects of this internally. Let me know if I'm missing something.

[bjoernQ]

URL changed: https://github.com/esp-rs/rust-build/releases/tag/v1.73.0.1
Shouldn't be private

[bjoernQ]

I think there must be a reason why there are cfg guards in those other functions - maybe just to log anything if we are not able to use c-variadics or it was crashing when trying to pass the variadics 🤔 t.b.h I don't really remember exactly

[bjoernQ]

Fixes #16

[bugadani]

it was crashing when trying to pass the variadics

I think I can test this, this is a fair point.

• 1.73.0.1 - several empty log strings, same as @AnthonyGrondin reports. turns out this is just some internal logging code being implemented weirdly. The code prints a \n at the end, in a separate printf call, as printf("%s", "\n") 😅
• 1.73.0.0
• 1.72.1.0
• 1.72.0.0

Update: no crash with current PR using supported rustc on esp32s3

[bugadani]

I've raised the level of puts from trace to info so it's the same as syslog (and thus, printf) now. I'm tempted to implement the level-based filtering for syslog but that would just be even more binary bloat.

[bjoernQ]

LGTM - Thanks!

[AnthonyGrondin]

Thank you for taking care of it.