Rust 1.90.0

Language

Split up the unknown_or_malformed_diagnostic_attributes lint. This lint has been split up into four finer-grained lints, with unknown_or_malformed_diagnostic_attributes now being the lint group that contains these lints:
1. unknown_diagnostic_attributes: unknown to the current compiler
2. misplaced_diagnostic_attributes: placed on the wrong item
3. malformed_diagnostic_attributes: malformed attribute syntax or options
4. malformed_diagnostic_format_literals: malformed format string literal
Allow constants whose final value has references to mutable/external memory, but reject such constants as patterns
Allow volatile access to non-Rust memory, including address 0

Refer to Rust's platform support page for more information on Rust's tiered platform support.

These previously stable APIs are now stable in const contexts:

Add ways to collapse all impl blocks. Previously the "Summary" button and "-" keyboard shortcut would never collapse impl blocks, now they do when shift is held
Display unsafe attributes with unsafe() wrappers

Use lld by default on x86_64-unknown-linux-gnu. See also https://blog.rust-lang.org/2025/09/01/rust-lld-on-1.90.0-stable/.
Make core::iter::Fuse's Default impl construct I::default() internally as promised in the docs instead of always being empty
Set for This may change program behavior but results in the same behavior as other primitives (e.g., stdout, network sockets). Programs relying on signals to terminate them should update handling of sockets to handle errors on write by exiting.