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use proc_macro2::{Punct, Spacing, TokenStream}; // None of our generated code requires the `From::from` error conversion // performed by the standard library's `try!` macro. With this simplified macro // we see a significant improvement in type checking and borrow checking time of // the generated code and a slight improvement in binary size. pub fn replacement() -> TokenStream { // Cannot pass `$expr` to `quote!` prior to Rust 1.17.0 so interpolate it. let dollar = Punct::new('$', Spacing::Alone); quote! { #[allow(unused_macros)] macro_rules! try { (#dollar __expr:expr) => { match #dollar __expr { _serde::__private::Ok(__val) => __val, _serde::__private::Err(__err) => { return _serde::__private::Err(__err); } } } } } }