Add the rest of Rust syntax behind a feature flag (off by default)

[dtolnay]

Parsing structs and enums is enough for Macros 1.1 but parsing all of Rust may be useful for other things.

Items

• ExternCrate
• Use
• Static
• Const
• Fn
• Mod
• ForeignMod
• Ty
• Enum (enabled by default)
• Struct (enabled by default)
• Union
• Trait
• DefaultImpl
• Impl
• Mac

Expressions

• Box
• Vec
• Call
• MethodCall
• Tup
• Binary
• Unary
• Lit
• Cast
• Type
• If
• IfLet
• While
• WhileLet
• ForLoop
• Loop
• Match
• Closure
• Block
• Assign
• AssignOp
• Field
• TupField
• Index
• Range
• Path
• AddrOf
• Break
• Continue
• Ret
• Mac
• Struct
• Repeat
• Paren
• Try

Statements

• Local
• Item
• Expr
• Semi
• Mac

Patterns

• Wild
• Ident
• Struct
• TupleStruct
• Path
• Tuple
• Box
• Ref
• Lit
• Range
• Slice
• Mac

Other

• Workaround for parsing ambiguity Disallow struct literals in ambiguous positions. rust-lang/rfcs#92

[dtolnay]

This would allow serde_codegen to drop its dependency on Syntex entirely.

[tikue]

In a plugin I'm using to transform idents, I need to parse traits, trait impls, and type paths. This is because macros can't perform an ident => ident transformation, so instead I have specialized versions of the macro for different contexts.

[gregkatz]

Hi! Could I work on parsing the loop expression? Maybe if I'm able to handle that one fairly easily, I can move on to others.

[dtolnay]

Absolutely! Thanks in advance. Let me know if I can help explain anything.