Fix non-deterministic error messages

CHANGELOG.md

@@ -6,6 +6,20 @@ All user visible changes to this project will be documented in this file. This p
 
 
 
+## [0.1.2] · ???
+[0.1.2]: /../../tree/v0.1.2
+
+[Diff](/../../compare/v0.1.1...v0.1.2)
+
+### Fixed
+
+- Non-deterministic error messages. ([#2])
+
+[#2]: /../../pull/2
+
+
+
+
 ## [0.1.1] · 2021-08-13
 [0.1.1]: /../../tree/v0.1.1
 

core/src/codegen/parse_attrs.rs

@@ -1,6 +1,6 @@
 //! `#[derive(ParseAttrs)]` proc macro implementation.
 
-use std::{collections::HashSet, convert::TryFrom, iter};
+use std::{collections::BTreeSet, convert::TryFrom, iter};
 
 use proc_macro2::{Span, TokenStream};
 use quote::{quote, ToTokens};
@@ -414,12 +414,12 @@ struct FieldAttrs {
  /// Names of [`syn::Attribute`]'s arguments to use for parsing __instead
  /// of__ the [`ParseAttrs`]'s field's [`syn::Ident`].
  // #[parse(value, alias = arg)]
- args: HashSet<syn::Ident>,
+ args: BTreeSet<syn::Ident>,
 
  /// Names of [`syn::Attribute`]'s arguments to use for parsing __along
  /// with__ the [`ParseAttrs`]'s field's [`syn::Ident`].
  // #[parse(value, alias = alias)]
- aliases: HashSet<syn::Ident>,
+ aliases: BTreeSet<syn::Ident>,
 
  /// [`dedup`]lication strategy of how multiple values of the
  /// [`ParseAttrs`]'s field should be merged.

tests/parse_attrs.rs

@@ -615,6 +615,70 @@ mod value {
  }
  }
 
+ mod required_aliased {
+ use synthez::Required;
+
+ use super::*;
+
+ #[derive(Debug, Default, ParseAttrs)]
+ struct Attr {
+ #[parse(value, alias = required)]
+ name: Required<syn::Ident>,
+ }
+
+ #[test]
+ fn allows_present() {
+ let input: syn::DeriveInput = syn::parse_quote! {
+ #[attr(name = minas)]
+ struct Dummy;
+ };
+
+ let res = Attr::parse_attrs("attr", &input);
+ assert!(res.is_ok(), "failed: {}", res.unwrap_err());
+
+ assert_eq!(
+ *res.unwrap().name,
+ syn::Ident::new_on_call_site("minas"),
+ );
+ }
+
+ #[test]
+ fn allows_alias() {
+ let input: syn::DeriveInput = syn::parse_quote! {
+ #[attr(required = tirith)]
+ struct Dummy;
+ };
+
+ let res = Attr::parse_attrs("attr", &input);
+ assert!(res.is_ok(), "failed: {}", res.unwrap_err());
+
+ assert_eq!(
+ *res.unwrap().name,
+ syn::Ident::new_on_call_site("tirith"),
+ );
+ }
+
+ #[test]
+ fn forbids_absent() {
+ let input: syn::DeriveInput = syn::parse_quote! {
+ struct Dummy;
+ };
+
+ let res = Attr::parse_attrs("attr", &input);
+ assert!(res.is_err(), "should fail, but is ok");
+
+ let err = res.unwrap_err().to_string();
+ assert!(
+ err.contains(
+ "either `name` or `required` argument of `#[attr]` \
+ attribute is expected to be present, but is absent",
+ ),
+ "wrong err:\n{}",
+ err,
+ );
+ }
+ }
+
  mod required_fallback {
  use synthez::{field, Required};