Bump rust to 1.94 and nightly to 2026-01-18

[kskalski]

Problem

New Rust toolchain is available

Summary of Changes

• Bump toolchain to 1.94 and nightly to 2026-01-18
• remove unsafe block around __cpuid checks (relaxed by Make cpuid safe and update docs rust-lang/stdarch#1935)

Fixes #11035

[mergify]

If this PR represents a change to the public RPC API:

1. Make sure it includes a complementary update to rpc-client/ (example)
2. Open a follow-up PR to update the JavaScript client @solana/kit (example)

Thank you for keeping the RPC clients in sync with the server API @kskalski.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 0% with 56 lines in your changes missing coverage. Please review.
✅ Project coverage is 83.2%. Comparing base (4a91f00) to head (e9a043b).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff            @@
##           master   #11218     +/-   ##
=========================================
- Coverage    83.2%    83.2%   -0.1%     
=========================================
  Files         841      841             
  Lines      318505   318505             
=========================================
- Hits       265189   265152     -37     
- Misses      53316    53353     +37     

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[brooksprumo]

[steviez]

Thanks for doing this. Process wise, we have historically landed code changes separately from the actual version bump when we can.

Is it correct that the code change here must land in the same commit as the Rust version bump ? Ie, is the code change invalid with Rust 1.93 ?

[kskalski]

Thanks for doing this. Process wise, we have historically landed code changes separately from the actual version bump when we can.

Sure, I'm aming for that whenever possible.

Is it correct that the code change here must land in the same commit as the Rust version bump ? Ie, is the code change invalid with Rust 1.93 ?

Exactly. I cannot remove the unsafe annotation first, since __cpuid is actually unsafe in 1.93, I also cannot keep the unsafe annotation after bump, since it triggers warning about unnecessary unsafe (unsafe was relaxed in rust-lang/stdarch#1935)

Of course the other strategy would be to allow the warning, make the bump, remove the allow... Feels like overdoing it, but maybe that would be preferred.