support std crate in VM programs.

[vivekvpandya]

For our custom target some operations from std crate is not supported. For example https://github.com/rust-lang/rust/blob/master/library/std/src/sys/unsupported/thread_local_key.rs#L5
Above code is used in panic_handler and itself panics creating infinite loop.

This issue is created to solve issues like above so that VM programs can use std crate.

[matthiasgoergens]

Perhaps see how Risc-Zero does it.

[vivekvpandya]

Perhaps see how Risc-Zero does it.

They maintain their own fork for Rust std lib. See https://github.com/risc0/rust/blob/risc0/library/panic_abort/src/lib.rs#L39
and https://github.com/risc0/risc0/blob/main/risc0/cargo-risczero/src/toolchain.rs#L27 (where this gets included)

[vivekvpandya]

https://github.com/0xmozak/rust/tree/mozak This fork of rust may help with this issue.

[vivekvpandya]

if in future we ever need to have native run with no_std then we can use my attached patch for starting guest related changes.
no_std_native.patch.txt