8e1f660e1d
# Objective Emitting compile errors produces cleaner messages than panicking in a proc-macro. ## Solution - Replace match-with-panic code with call to new `bevy_macro_utils::get_named_struct_fields` function - Replace one use of match-with-panic for enums with inline match _Aside:_ I'm also the maintainer of [`darling`](https://docs.rs/darling), a crate which provides a serde-like API for parsing macro inputs. I avoided using it here because it seemed like overkill, but if there are plans to add lots more attributes/macros then that might be a good way of offloading macro error handling.
21 lines
851 B
Rust
21 lines
851 B
Rust
use proc_macro::Span;
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use syn::{Data, DataStruct, Error, Fields, FieldsNamed};
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/// Get the fields of a data structure if that structure is a struct with named fields;
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/// otherwise, return a compile error that points to the site of the macro invocation.
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pub fn get_named_struct_fields(data: &syn::Data) -> syn::Result<&FieldsNamed> {
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match data {
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Data::Struct(DataStruct {
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fields: Fields::Named(fields),
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..
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}) => Ok(fields),
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_ => Err(Error::new(
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// This deliberately points to the call site rather than the structure
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// body; marking the entire body as the source of the error makes it
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// impossible to figure out which `derive` has a problem.
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Span::call_site().into(),
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"Only structs with named fields are supported",
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)),
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}
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}
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