Draft release notes for 1.98.0

[BoxyUwU]

NOTE: Use the 📝 links to edit those that have a relnotes-tracking-issue,
and they will be updated when we regenerate the notes periodically (manually).

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Version 1.98.0 (2026-08-20)

Language

• Allow shortening lifetime of &mut when unsize-coercing, even in an invariant position. For example, you can now coerce a Cell<&'long mut i32> to a Cell<&'short mut dyn Send>. Such shortenings were already previously allowed when coercing a &mut to a &, or coercing a & to a &.
  📝
• riscv: d, e, and f target_features are now stable in cfg(target_feature = "?")
  📝

Compiler

Platform Support

• Add powerpc64-unknown-linux-gnuelfv2 as Tier 3
  📝
• Add aarch64-unknown-linux-pauthtest as Tier 3 target
  📝
• Promote thumbv7a-none-eabi Tier 2
• Promote thumbv7a-none-eabihf Tier 2
• Promote thumbv7r-none-eabi Tier 2
• Promote thumbv7r-none-eabihf Tier 2
• Promote thumbv8r-none-eabihf Tier 2
  📝

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

Libraries

• Change Location<'_> lifetime to 'static in Panic[Hook]Info
  📝
• Document panic in RangeInclusive::from(legacy::RangeInclusive)
  📝
• Document that ManuallyDrop's Box interaction has been fixed
  📝
• Stabilize core::range::{legacy, RangeFull, RangeTo}

Stabilized APIs

• core::fmt::NumBuffer
• <{integer}>::format_into
  📝
• Send/Sync for std::process::CommandArgs
  📝
• {fN}::algebraic_add
• {fN}::algebraic_sub
• {fN}::algebraic_mul
• {fN}::algebraic_div
• {fN}::algebraic_rem
  📝
• NonZero<{integer}>::from_str_radix
  📝
• String::from_utf16le
• String::from_utf16le_lossy
• String::from_utf16be
• String:;from_utf16be_lossy
  📝
• [T]::strip_circumfix
• str::strip_circumfix
  📝
• Atomic<T>::from_mut
• Atomic<T>::get_mut_slice
• Atomic<T>::from_mut_slice
  📝

These previously stable APIs are now stable in const contexts:

Cargo

Rustdoc

Compatibility Notes

• If fully elided, lifetime bounds of trait object types may now resolve differently or even get rejected in very specific niche scenarios
  📝
• Error in more cases of ambiguous imports
  📝
• Switch the destructors implementation for thread locals on Windows to use FLS
  📝
• Convert some cases of the ambiguous_glob_imports lint into a hard error
  📝
• Where-bounds of the form Type = Type and Type == Type are no longer syntactically allowed
  📝
• Ensure Send/Sync is not implemented for std::env::Vars{,Os}
  📝
• Fix that in some attributes, arguments were not properly rejected
  📝
• repr(transparent) is now more strict about which fields have "trivial" layout and hence can be ignored: repr(C) types, types with private fields, and #[non_exhaustive] types are no longer considered "trivial"
  📝
• Correctly check whether types have equal size in transmute() when some repr attributes are involved.
  📝
• Add deny-by-default invalid_runtime_symbol_definitions lint and warn-by-default suspicious_runtime_symbol_definitions lint
  • The lints currently specifically targets core runtime symbols like memcmp, memset, strlen, ... and is planned be embellished in the next few releases.
    📝
• More characters are escaped when printing strings an chars
  📝
• Implement fast path for derive(PartialOrd) when deriving Ord
  This can break crates in practice where a type's PartialOrd and Ord impls were inconsistent with each other.
  📝
• Add temporary scope to assert_eq and assert_ne
  📝
• lint on core::ffi::c_void as a return type
  📝
• Closed a hole in the pattern matching structural equality check, preventing cases where a match of a constant would be allowed, despite disagreeing with a manually written PartialEq implementation, when a derive(PartialEq) implementation for that type also exists.
  📝
• On Emscripten the WASM exception handling ABI is now unconditionally used The -Zemscripten-wasm-eh=false flag to switch back to JS exceptions has been removed.
  📝
• The UNSAFE_CODE lint is now consistently emitted for all unsafe attributes
  📝
• Solaris: remove File::lock implementation, it has the wrong semantics (return "unsupported" instead)
  📝
• Windows-gnu targets now specify baseline tools versions
  📝

Internal Changes

These changes do not affect any public interfaces of Rust, but they represent
significant improvements to the performance or internals of rustc and related
tools.

Other

[BoxyUwU]

cc @rust-lang/release

@rustbot ping relnotes-interest-group

[rustbot]

Hi relnotes-interest-group, this issue/PR could use some help in reviewing /
adjusting release notes. Could you take a look if available? Thanks <3

cc @alex-semenyuk @jieyouxu @joshtriplett @lcnr @traviscross @weihanglo