5b485f04de
Disallow cast with trailing braced macro in let-else This fixes an edge case I noticed while porting #118880 and #119062 to syn. Previously, rustc incorrectly accepted code such as: ```rust let foo = &std::ptr::null as &'static dyn std::ops::Fn() -> *const primitive! { 8 } else { return; }; ``` even though a right curl brace `}` directly before `else` in a `let...else` statement is not supposed to be valid syntax.
The rustc_ast crate contains those things concerned purely with syntax
– that is, the AST ("abstract syntax tree"), along with some definitions for tokens and token streams, data structures/traits for mutating ASTs, and shared definitions for other AST-related parts of the compiler (like the lexer and macro-expansion).
For more information about how these things work in rustc, see the rustc dev guide: