3d559d8b41
Missing whitespace in the implementation of `TokenStream::to_string` on beta and nightly was breaking our parsing of derive macro attributes. This change makes the parser ignore whitespace, and should make the beta and nightly builds succeed again.
62 lines
2.0 KiB
Rust
62 lines
2.0 KiB
Rust
extern crate proc_macro;
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use crate::proc_macro::TokenStream;
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use quote::quote;
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use syn::{parse_macro_input, DeriveInput};
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/// Returns true if some field has an attribute declaring it should be generated from default (not
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/// randomized).
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///
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/// The field attribute is: `#[test_random(default)]`
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fn should_use_default(field: &syn::Field) -> bool {
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field.attrs.iter().any(|attr| {
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attr.path.is_ident("test_random") && attr.tts.to_string().replace(" ", "") == "(default)"
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})
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}
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#[proc_macro_derive(TestRandom, attributes(test_random))]
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pub fn test_random_derive(input: TokenStream) -> TokenStream {
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let derived_input = parse_macro_input!(input as DeriveInput);
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let name = &derived_input.ident;
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let (impl_generics, ty_generics, where_clause) = &derived_input.generics.split_for_impl();
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let struct_data = match &derived_input.data {
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syn::Data::Struct(s) => s,
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_ => panic!("test_random_derive only supports structs."),
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};
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// Build quotes for fields that should be generated and those that should be built from
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// `Default`.
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let mut quotes = vec![];
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for field in &struct_data.fields {
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match &field.ident {
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Some(ref ident) => {
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if should_use_default(field) {
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quotes.push(quote! {
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#ident: <_>::default(),
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});
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} else {
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quotes.push(quote! {
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#ident: <_>::random_for_test(rng),
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});
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}
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}
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_ => panic!("test_random_derive only supports named struct fields."),
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};
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}
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let output = quote! {
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impl #impl_generics TestRandom for #name #ty_generics #where_clause {
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fn random_for_test(rng: &mut impl rand::RngCore) -> Self {
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Self {
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#(
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#quotes
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)*
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}
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}
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}
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};
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output.into()
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}
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