darling

• Bump MSRV to 1.88.0; there have been no code changes that caused this, but due to dependency issues CI no longer works on 1.56.0 #357
• Revert dependency version pins which caused problems #385

YANKED Pinned dependencies made this version cause conflicts with other crates.

• BREAKING: Remove fnv dependency, as runtime performance gain does not justify additional dependency. This was exposed to users of darling::usage, so it may be breaking for them #373
• Add #[darling(default = || expr(val))] support, allowing a closure where a path was previously required #380
• Preserve span information for paths given to darling::util::Callable as literal strings
• Fix some documentation typos

• Fix: Forward Override::<T>::from_expr to T::from_expr #371

• Add #[darling(from_expr = ...)] when deriving FromMeta to support overriding the key-value form #369
• Keep parsing the body and type params even if there are errors from parsing attributes. #7
• Support #[darling(with = ...)] on the generics field when deriving FromDeriveInput.
• Return an error, rather than panicking, when doing shape validation on a union. #365

• Track all alternate field names, and show them in error message if there aren't too many. #325
• Track all alternate values for enum variants, and show them in error messages if there aren't too many. #362

• Potentially breaking: Emit error when an attribute path is present in both attributes and forward_attrs. #336
• Support parsing attributes which contain keywords #238
• Add SpannedValue::into_inner #342
• Add #[darling(derive_syn_parse)] to also impl syn::parse::Parse when deriving FromMeta #285
• Make impl FromMeta for syn::TypePath support both quote-wrapped and bare values #351
• Add util::PreservedStrExpr #346
• Impl UsesTypeParams and UsesLifetimes for WithOriginal #215
• Update error message emitted by <() as FromMeta>::from_list to allow use of () as a #[darling(flatten)] target #353

• Support #[darling(with = ...)] on the data field when deriving FromDeriveInput. This allows the use of simpler receiver types, such as a Vec of enum variants.
• Bump version of proc-macro2 to 1.0.86.
• Accept closures for #[darling(with = ...)] on fields in FromDeriveInput, FromMeta, FromField, etc. #309
• Add darling::util::Callable to accept a path or closure as a meta-item expression
• Add #[darling(from_word = ...)] and #[darling(from_none = ...)] to control shorthand and fallback behaviors for structs and enums deriving FromMeta #320
• Add FromMeta impl for syn::ExprRange #329

• Add #[allow(clippy::manual_unwrap_or_default)] to all generated impls to avoid causing clippy fails in crates using darling #296
• Properly initialize attrs magic field in derived FromAttributes impls #297

• Allow word-form for newtype enum variants whose only field produces a value when from_none is called on their type #249
• Add FromMeta impls for the std::num::NonZero* types #288
• Fix panic in number FromMeta impls when the parsed value is too large for the receiver type #289

• Add #[darling(with = ...)] support to attrs magic field to allow using custom receiver types for attrs #273

• Add #[darling(flatten)] to allow forwarding unknown fields to another struct #146
• Don't suggest names of skipped fields in derived impls #268

• Fix some missing syn invisible group handling in FromMeta impls #263
• Fix misleading error message on Error::unexpected_type so it no longer implies the type was a literal #264
• Impl FromMeta Vec of literals, e.g. LitStr #265

• Add Flag::span inherent method, as Flag can no longer impl syn::spanned::Spanned #242

• Accept bare paths in #[darling(default = ...)] #258
• Add FromMeta impl for PathBuf #259
• Improve FromMeta implementation for enums #260
  • Properly implement unit arms in FromMeta::from_list to provide a consistent API for heterogeneous enums that include a mix of unit, newtype and struct variants
  • Add #[darling(word)] attribute for unit enum variants (See #63 for details)

• Add FromMeta impl for u128 and i128 #243

• Add Clone impl for NestedMeta #230

• Bump syn to version 2, courtesy of @jonasbb #227

Breaking Changes

• Replace all occurrences of syn::NestedMeta with darling::ast::NestedMeta.

• Replacement for the deprecated AttributeArgs:

// Before

parse_macro_input!(args as AttributeArgs);

// After

match NestedMeta::parse_meta_list(args) {
    Ok(v) => v,
    Err(e) => {
      return TokenStream::from(Error::from(e).write_errors());
    }
};

• In GenericParamExt, LifetimeDef is now LifetimeParam.
• In GenericParamExt, as_lifetime_def is renamed to as_lifetime_param.
• Flag and SpannedValue no longer implement syn::spanned::Spanned.
• The MSRV (minimum supported Rust version) is now 1.56, because of syn.

Deprecation Warnings

In previous versions of darling, arbitrary expressions were passed in attributes by wrapping them in quotation marks. v0.20.0 preserves this behavior for syn::Expr, but as a result a field expecting a syn::Expr cannot accept a string literal - it will incorrectly attempt to parse the contents. If this is an issue for you, please add a comment to #229.

• Add support for child diagnostics when diagnostics feature enabled #224

• Re-export syn from darling to avoid requiring that consuming crates have a syn dependency.
• Change <SpannedValue<T> as FromMeta> impl to more precisely capture the value span, as opposed to the span of the entire item.
• Add darling::util::{AsShape, Shape, ShapeSet} to improve "shape" validation for structs and variants. #222

• Derived impls of FromMeta will now error on literals, rather than silently ignoring them. #193
• Don't include property paths in compile errors when spans are available. #203

• Fix a bug where using a trait that accepts #[darling(attributes(...))] without specifying any attributes would emit code that did not compile. #183
• Impl Clone for darling::Error #184
• Impl From<darling::Error> for syn::Error #184
• Add Error::span and Error::explicit_span methods #184

• BREAKING CHANGE: Remove many trait impls from util::Flag. This type had a number of deref and operator impls that made it usable as sort-of-a-boolean. Real-world usage showed this type is more useful if it's able to carry a span for good errors, and that most of those impls were unnecessary. #179
• Remove need for #[darling(default)] on Option<T> and Flag fields #161
• Improve validation of enum shapes #178
• Bump proc-macro2 dependency to 1.0.37 #180
• Bump quote dependency to 1.0.18 #180
• Bump syn dependency to 1.0.91 #180

• Impl FromMeta for syn::Visibility #173

• Add error::Accumulator for dealing with multiple errors #164
• Impl FromMeta for syn::Type and its variants #172

• Impl FromMeta for syn::ExprPath #169

• Add FromAttributes trait and macro #151

• Update darling to 2018 edition #129
• Error on duplicate fields in #[darling(...)] attributes #130
• Impl Copy for SpannedValue<T: Copy>
• Add SpannedValue::map_ref

• Update darling to 2018 edition #129
• Error on duplicate fields in #[darling(...)] attributes #130

• Add and_then to derive macros for darling

• Fix FromMeta impl for char not to panic #126

• Impl FromMeta for HashMap<Ident, V> and HashMap<Path, V>

• Impl FromMeta for syn::ExprArray #122
• Remove use of unreachable from darling::ast::Data #123
• Add darling::ast::Data::try_empty_from to avoid panics when trying to read a union body #123

• POSSIBLY BREAKING: Derived impls of FromDeriveInput, FromField, FromVariant, and FromTypeParam will now error when encountering an attribute darling has been asked to parse that isn't a supported shape. Any crates using darling that relied on those attributes being silently ignored could see new errors reported in their dependent crates. #113
• Impl syn::spanned::Spanned for darling::util::SpannedValue #113
• Add darling::util::parse_attribute_to_meta_list to provide useful errors during attribute parsing #113
• Add impl From<syn::Error> for Error to losslessly propagate syn errors #116

• Bump minor version due to unexpected breaking change #107

• Add discriminant magic field when deriving FromVariant #105

• Bump syn dependency to 1.0.1 #83

• Fix test compilation errors #81

• Bump syn and quote to 1.0 #79
• Increase rust version to 1.31

• Enable "did you mean" suggestions by default
• Make darling_core::{codegen, options} private #58
• Fix Override::as_mut: #66

• Added "did you mean" suggestions for unknown fields behind the suggestions flag #60
• Added Error::unknown_field_with_alts to support the suggestion use-case.
• Added ast::Fields::len and ast::Fields::is_empty methods.

• Accept unquoted positive numeric literals #52
• Add FromMeta to the syn::Lit enum and its variants
• Improve error message for unexpected literal formats to not say "other"

• Use syn::Error to provide precise errors before proc_macro::Diagnostic is available
• Add diagnostics feature flag to toggle between stable and unstable error backends
• Attach error information in more contexts
• Add allow_unknown_fields to support parsing the same attribute multiple times for different macros #51
• Proc-macro authors will now see better errors in darling attributes

• Attach spans to errors in generated trait impls #37
• Attach spans to errors for types with provided bespoke implementations
• Deprecate set_span from 0.8.2, as spans should never be broadened after being initially set

• Add spans to errors to make quality warnings and errors easy in darling. This is blocked on diagnostics stabilizing.
• Add darling::util::SpannedValue so proc-macro authors can remember position information alongside parsed values.

• Update dependency on syn to 0.15 #44. Thanks to @hcpl

• Update dependencies on syn and proc-macro2
• Add util::IdentString, which acts as an Ident or its string equivalent

• Add support for Uses* traits in where predicates

• Add usage module for tracking type param and lifetime usage in generic declarations
  • Add UsesTypeParams and CollectsTypeParams traits #37
  • Add UsesLifetimes and CollectLifetimes traits #41
• Don't add FromMeta bounds to type parameters only used by skipped fields #40

• Fix an issue where the syn update broke shape validation #36

Breaking Changes

• Renamed FromMetaItem to FromMeta, and renamed from_meta_item method to from_meta
• Added dedicated derive(FromMetaItem) which panics and redirects users to FromMeta

• Add ast::Generics and ast::GenericParam to work with generics in a manner similar to ast::Data
• Add ast::GenericParamExt to support alternate representations of generic parameters
• Add util::WithOriginal to get a parsed representation and syn's own struct for a syntax block
• Add FromGenerics and FromGenericParam traits (without derive support)
• Change generated code for generics magic field to invoke FromGenerics trait during parsing
• Add FromTypeParam trait #30. Thanks to @upsuper

• Update dependencies on proc-macro, quote, and syn #26. Thanks to @hcpl

YANKED

• Derive Default on darling::Ignored (fixes #25).

• Support proc-macro2/nightly #24. Thanks to @kdy1

Breaking Changes

• Update syn to 0.12 #20. Thanks to @Eijebong
• Update quote to 0.4 #20. Thanks to @Eijebong
• Rename magic field body in derived FromDeriveInput structs to data to stay in sync with syn
• Rename magic field data in derived FromVariant structs to fields to stay in sync with syn

• Update lazy_static to 1.0 #15. Thanks to @Eijebong