pretty_error_debug_derive/
lib.rs

1// SPDX-License-Identifier: MIT OR Apache-2.0 WITH LLVM-exception
2
3//! Derive macro for `pretty_error_debug`
4
5extern crate proc_macro;
6
7use proc_macro::TokenStream;
8use quote::quote_spanned;
9use syn::{parse_macro_input, DeriveInput};
10
11/// Derive `std::fmt::Debug` using `pretty_error_debug`
12///
13/// For `struct MyError` this code would be derived:
14///
15/// ```rust
16/// #   struct MyError;
17/// #   impl std::error::Error for MyError {}
18/// #   impl std::fmt::Display for MyError {
19/// #       fn fmt(&self, _: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
20/// #           Ok(())
21/// #       }
22/// #   }
23/// impl std::fmt::Debug for MyError {
24///     #[inline]
25///     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
26/// #       /*
27///         pretty_error_debug::pretty_error_debug(self, f)
28/// #       */ Ok(())
29///     }
30/// }
31/// ```
32#[proc_macro_derive(PrettyDebug)]
33pub fn pretty_error_debug_derive_debug(input: TokenStream) -> TokenStream {
34    let input = parse_macro_input!(input as DeriveInput);
35    let ident = &input.ident;
36    let span = ident.span();
37
38    let (impl_generics, ty_generics, where_clause) = input.generics.split_for_impl();
39    TokenStream::from(quote_spanned! {
40        span =>
41        const _: () = {
42            #[automatically_derived]
43            #[allow(unused_qualifications)]
44            impl #impl_generics pretty_error_debug::core::fmt::Debug
45            for #ident #ty_generics #where_clause
46            {
47                #[inline]
48                fn fmt(
49                    &self,
50                    f: &mut pretty_error_debug::core::fmt::Formatter<'_>,
51                ) -> pretty_error_debug::core::fmt::Result {
52                    pretty_error_debug::pretty_error_debug(self, f)
53                }
54            }
55        };
56    })
57}
pretty_error_debug_derive/lib.rs

pretty_error_debug_derive/
lib.rs
