chore: bump syn from 2.0.118 to 3.0.2

[dependabot]

Bumps syn from 2.0.118 to 3.0.2.

Release notes

Sourced from syn's releases.

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

• In Expr::Closure, the fields or1_token and or2_token have been renamed to inputs_begin and inputs_end to indicate the beginning and ending | token of the closure inputs.

... (truncated)

Commits

• 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
• c6ac5e5 Merge pull request #2068 from dtolnay/newrange
• 1436454 Add Error::new_range constructor taking Range<Cursor>
• 123c148 Release 3.0.1
• bc11ddd Merge pull request #2067 from dtolnay/fastpeek
• Additional commits viewable in compare view

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[Copilot]

Pull request overview

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Updates the Rust dependency on syn, apparently attempting a major-version upgrade.

Changes:

• Bumped syn from 2.0.111 to 3.0.2 in Cargo.toml.

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[Vaiz]

@copilot, do a proper migration

[Copilot]

@copilot, do a proper migration

Done. Here's what the proper migration involved (commit fix: migrate templated_uri_macros_impl and thread_aware_macros_impl to syn 3.x):

1. templated_uri_macros_impl: Removed the darling dependency (darling 0.23 still depends on syn 2.x) and replaced #[derive(FromAttributes)] / #[derive(FromField)] with manual parse_nested_meta-based parsing using syn 3.x. Added explicit syn features (derive, full, parsing, printing, proc-macro) to the crate's Cargo.toml.

2. prettyplease: Bumped from 0.2.37 to 0.3.0 — the syn 3.x-compatible version released last Friday.

3. thread_aware_macros_impl tests: Fixed a TypeGroup struct literal that was missing the new attrs: Vec<Attribute> field added in syn 3.x.

All crates build and tests pass. The only remaining syn 2.x in the lockfile is from external transitive dependencies (async-trait, serde_derive, Azure SDK crates, etc.) that we don't control.

[martintmk]

I think is a case where we should wait for crates that depend on new syn 3.0 to catch-up and then do the switch. No need to rush.

For example, darling is already being upgraded:
TedDriggs/darling#431