Sourced from rust-toolchain's releases.

Rust 1.91.0

Language

• Lower pattern bindings in the order they're written and base drop order on primary bindings' order
• Stabilize declaration of C-style variadic functions for sysv64, win64, efiapi, and aapcs ABIs. This brings these ABIs in line with the C ABI: variadic functions can be declared in extern blocks but not defined.
• Add dangling_pointers_from_locals lint to warn against dangling pointers from local variables
• Upgrade semicolon_in_expressions_from_macros from warn to deny
• Stabilize LoongArch32 inline assembly
• Add warn-by-default integer_to_ptr_transmutes lint against integer-to-pointer transmutes
• Stabilize sse4a and tbm target features
• Add target_env = "macabi" and target_env = "sim" cfgs as replacements for the target_abi cfgs with the same values.

Compiler

• Don't warn on never-to-any as casts as unreachable

Platform Support

• Promote aarch64-pc-windows-gnullvm and x86_64-pc-windows-gnullvm to Tier 2 with host tools. Note: llvm-tools and MSI installers are missing but will be added in future releases.
• Promote aarch64-pc-windows-msvc to Tier 1

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

Libraries

• Print thread ID in panic message
• Fix overly restrictive lifetime in core::panic::Location::file return type
• Guarantee parameter order for _by() variants of min / max/ minmax in std::cmp
• Document assumptions about Clone and Eq traits
• std::thread: Return error if setting thread stack size fails This used to panic within the standard library.

Stabilized APIs

• Path::file_prefix
• AtomicPtr::fetch_ptr_add
• AtomicPtr::fetch_ptr_sub
• AtomicPtr::fetch_byte_add
• AtomicPtr::fetch_byte_sub
• AtomicPtr::fetch_or
• AtomicPtr::fetch_and

... (truncated)

Sourced from rust-toolchain's changelog.

Version 1.91.0 (2025-10-30)

Language

• Lower pattern bindings in the order they're written and base drop order on primary bindings' order
• Stabilize declaration of C-style variadic functions for sysv64, win64, efiapi, and aapcs ABIs. This brings these ABIs in line with the C ABI: variadic functions can be declared in extern blocks but not defined.
• Add dangling_pointers_from_locals lint to warn against dangling pointers from local variables
• Upgrade semicolon_in_expressions_from_macros from warn to deny
• Stabilize LoongArch32 inline assembly
• Add warn-by-default integer_to_ptr_transmutes lint against integer-to-pointer transmutes
• Stabilize sse4a and tbm target features
• Add target_env = "macabi" and target_env = "sim" cfgs as replacements for the target_abi cfgs with the same values.

Compiler

• Don't warn on never-to-any as casts as unreachable

Platform Support

• Promote aarch64-pc-windows-gnullvm and x86_64-pc-windows-gnullvm to Tier 2 with host tools. Note: llvm-tools and MSI installers are missing but will be added in future releases.
• Promote aarch64-pc-windows-msvc to Tier 1

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

Libraries

• Print thread ID in panic message
• Fix overly restrictive lifetime in core::panic::Location::file return type
• Guarantee parameter order for _by() variants of min / max/ minmax in std::cmp
• Document assumptions about Clone and Eq traits
• std::thread: Return error if setting thread stack size fails This used to panic within the standard library.

... (truncated)

• f8297e3 Auto merge of #148216 - cuviper:stable-next, r=BoxyUwU,jackh726
• faf3e0b Further revert Deref for Cow to its 1.90.0 state
• 40c4f6d Auto merge of #148179 - cuviper:stable-next, r=cuviper
• be999ad 1.91.0 stable release
• e4f5031 fix(len_zero): don't eagerly call GenericArgs::type_at (#15660)
• 7ce3022 rustdoc-search: stringdex 0.0.2
• 716b84e rustdoc-search: stringdex update with more packing
• b0dd64f rustdoc-search: add descriptive comment to space-saving hack
• 8127760 rustdoc-search: use the same ID for entry and path to same item
• b77c3b1 rustdoc-search: delay loading type name IDs until type search
• Additional commits viewable in compare view

You can trigger Dependabot actions by commenting on this PR:

• @dependabot rebase will rebase this PR
• @dependabot recreate will recreate this PR, overwriting any edits that have been made to it
• @dependabot merge will merge this PR after your CI passes on it
• @dependabot squash and merge will squash and merge this PR after your CI passes on it
• @dependabot cancel merge will cancel a previously requested merge and block automerging
• @dependabot reopen will reopen this PR if it is closed
• @dependabot close will close this PR and stop Dependabot recreating it. You can achieve the same result by closing it manually
• @dependabot show <dependency name> ignore conditions will show all of the ignore conditions of the specified dependency
• @dependabot ignore this major version will close this PR and stop Dependabot creating any more for this major version (unless you reopen the PR or upgrade to it yourself)
• @dependabot ignore this minor version will close this PR and stop Dependabot creating any more for this minor version (unless you reopen the PR or upgrade to it yourself)
• @dependabot ignore this dependency will close this PR and stop Dependabot creating any more for this dependency (unless you reopen the PR or upgrade to it yourself)