Crate debug_span

This crate provides a simple way to debug proc-macro2 spans. It is useful when you are working with procedural macros and you want to see the location of a span in the source code. It can be used for testing or debugging.

Example

use debug_span::debug_span;
use syn::spanned::Spanned;
use syn::Data;
use unindent::Unindent;

let input = r###"
    struct Foo {
        a: i32,
        b: i32,
    }
"###
.unindent();
let derive_input: syn::DeriveInput = syn::parse_str(&input).unwrap();
let span = match derive_input.data {
    Data::Struct(s) => s.fields.span(),
    _ => panic!("expected struct"),
};
     
let output = debug_span(span, &input);
insta::assert_snapshot!(output, @r###"
 --> 1:11..4:1
  |
  |            ┌────╮
1 | struct Foo {    │
2 |     a: i32,     │
3 |     b: i32,     │
4 | }               │
  | └───────────────╯
  |
"###);

Traits

• Span
  A trait for types that represent a span in the source code.

Functions

• debug_span
  Generate a debug representation of a span and the source code it points to.