[dependabot]

Bumps syn from 2.0.119 to 3.0.3.

Release notes

Sourced from syn's releases.

3.0.3

• Documentation improvements

3.0.2

• Add Error::new_range(start..end, "msg") (#2068, #2070)
• Add Cursor::prev_span

3.0.1

• Parse const traits (#2056, #2057, #2058, #2063, #2064)
• Parse unsafe binder types (#2065)
• Parse impl restrictions (#2066)

3.0.0

This release contains adjustments to the syntax tree to account for ongoing Rust language development from the 3 years since syn 2.0.0 and to anticipate some in-flight Rust language RFCs.

These include: default values in fields, pinned type sugar, raw lifetimes, generator blocks and functions, unnamed enum variants, attributes in tuple types and tuple patterns, named arguments in parenthesized generic argument lists, lightweight clones, const traits, const function pointers, mutability restricted fields, supertrait auto implementation, final associated functions, trait implementability restrictions, const blocks in path arguments, item-level const blocks, return type notation, never patterns, function delegation, mutable by-reference bindings, in-place initialization, field projections, explicitly dyn-compatible traits, view types, file-level frontmatter, generic const arguments, guard patterns, lazy type aliases, explicitly safe foreign items, super let, unsafe fields, pattern types, heterogeneous try-blocks, function contracts, async function trait bounds, static closure coroutine syntax, unsafe binder types, move expressions, for-await loops, and postfix keywords.

Breaking changes

Modifiers

To reserve more room for language evolution, there are 10 new non-exhaustive structs in the syntax tree having the following commonality:

• Name ending in Modifiers. {BlockModifiers, ClosureModifiers, ConstModifiers, FieldModifiers, FnModifiers, ImplModifiers, LocalModifiers, TraitBoundModifiers, TraitModifiers, TypeModifiers}

• Each implements Default. The default value is guaranteed to comprise no tokens.

• Non-exhaustive. Can only be instantiated by Syn's parser or by creating and then mutating ▁▁Modifiers::default().

• Does not implement Parse. When parsing, they are parsed by the enclosing syntax tree node.

• Does not implement ToTokens. In some cases the syntax that these nodes might hold in the future is not necessarily contiguous tokens.

• Provides .require_empty() -> Result<()> which returns a meaningfully spanned error if the modifiers are different from the empty default. This enables a caller to reject syntax it does not recognize without knowing what that syntax may be.

Types

• Type::BareFn has been renamed to Type::FnPtr to mirror the compiler's terminology. Together with this, BareVariadic is renamed to FnPtrVariadic.

• The mutually exclusive const_token and mutability fields of Type::Ptr have been unified into an enum of type PointerMutability, which was already previously used by Expr::RawAddr.

• Every Type variant now holds attributes, which can represent the attributes of element types inside a tuple type, or attributes for a function return type.

• BareFnArg is renamed to NamedArg and is used in ParenthesizedGenericArguments, in addition to the existing use in Type::FnPtr.

Expressions

... (truncated)

Commits

• 23dbaab Release 3.0.3
• 16aad4e Merge pull request #2071 from dtolnay/compatibility
• 42181b8 Add explanation of compatibility strategy
• f3af08e Update test suite to nightly-2026-07-21
• 88ee7be Release 3.0.2
• 587bc20 Merge pull request #2070 from dtolnay/emptyrange
• 96801f7 Allow Error::new_range at empty cursor range
• 9dc16c9 Merge pull request #2069 from dtolnay/prevspan
• 1db76b7 Align on using impl trait across all Error constructors
• bfa1ebf Make Cursor::prev_span public
• Additional commits viewable in compare view

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[chatgpt-codex-connector]

Keep syn aligned with syn-ext

This makes rustpython-derive-impl depend directly on syn 3 while syn-ext 0.5.0 still depends on syn 2.0.119 (as recorded in Cargo.lock), but the crate mixes both APIs—for example, pymodule.rs:45-71 passes a syn 3 ParseStream to syn_ext::types::NestedMeta, whose Parse implementation belongs to syn 2. Consequently the derive crate, and therefore the workspace, cannot compile; keep syn 2 until syn-ext supports syn 3, or migrate away from the syn 2 extension types in the same change.

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[fanninpm]

TODO(me): put syn and syn-ext into a new dependency group.