feat(wasm-builder): add support for new wasm32v1-none target

[StackOverflowExcept1on]

Description

Resolves #5777

Previously wasm-builder used hacks such as -Zbuild-std (required rust-src component) and RUSTC_BOOTSTRAP=1 to build WASM runtime without WASM features: sign-ext, multivalue and reference-types, but since Rust 1.84 (will be stable on 9 January, 2025) the situation has improved as there is new wasm32v1-none target that disables all "post-MVP" WASM features except mutable-globals.

Previously, your rust-toolchain.toml looked like this:

[toolchain]
channel = "stable"
components = ["rust-src"]
targets = ["wasm32-unknown-unknown"]
profile = "default"

It should now be updated to something like this:

[toolchain]
channel = "beta"
targets = ["wasm32v1-none"]
profile = "default"

To build the runtime:

cargo build --package minimal-template-runtime --release

Integration

If you are using Rust 1.84 and above, then install the wasm32v1-none target instead of wasm32-unknown-unknown as shown above. You can also remove the unnecessary rust-src component.

Also note the slight differences in conditional compilation:

• wasm32-unknown-unknown: #[cfg(all(target_family = "wasm", target_os = "unknown"))]
• wasm32v1-none: #[cfg(all(target_family = "wasm", target_os = "none"))]

Avoid using target_os = "unknown" in #[cfg(...)] or #[cfg_attr(...)] and instead use target_family = "wasm" or target_arch = "wasm32" in the runtime code.

Review Notes

Wasm builder requires the following prerequisites for building the WASM binary:

• Rust >= 1.68 and Rust < 1.84:
  • wasm32-unknown-unknown target
  • rust-src component
• Rust >= 1.84:
  • wasm32v1-none target
  • no more -Zbuild-std and RUSTC_BOOTSTRAP=1 hacks and rust-src component requirements!

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