Which toolchain should I use to build Substrate

Question

My current toolchains and targets look like this

installed toolchains
--------------------

stable-x86_64-unknown-linux-gnu (default)
nightly-2022-01-01-x86_64-unknown-linux-gnu
nightly-x86_64-unknown-linux-gnu

installed targets for active toolchain
--------------------------------------

wasm32-unknown-unknown
x86_64-pc-windows-gnu
x86_64-unknown-linux-gnu

active toolchain
----------------

stable-x86_64-unknown-linux-gnu (default)
rustc 1.60.0 (7737e0b5c 2022-04-04)

Should I use stable or nightly?

Answer 1

TL;DR: you likely should use the latest of both stable and nightly when building Substrate chains at any given time. Update regularly with rustup update.

It is quite likely the toolchain you should use for a given tag/release of Substrate (like polkadot-v0.9.19) is best discovered in the:

• release notes of Polkadot,
• Polkadot release branch nix.sh configuration in the Substrate,
• or the .gitlab-ci.yml target image used to do regular builds (matching the Substrate version you are using to the version of the image) and inspect it's nightly version.

You need both the stable and nightly, specifically nightly for the Wasm build, that is required for now (but not forever we expect).