chore: checkpoint before Python removal

vendor/darling_core/src/util/callable.rs

@@ -0,0 +1,62 @@
+use quote::ToTokens;
+
+use crate::{Error, FromMeta, Result};
+
+/// Either a path or a closure.
+///
+/// This type is useful for options that historically took a path,
+/// e.g. `#[darling(with = ...)]` or `#[serde(skip_serializing_if = ...)]`
+/// and now want to also allow using a closure to avoid needing a separate
+/// function declaration.
+///
+/// In `darling`, this value is wrapped in [`core::convert::identity`] before usage;
+/// this allows treatment of the closure and path cases as equivalent, and prevents
+/// a closure from accessing locals in the generated code.
+#[derive(Debug, Clone)]
+pub struct Callable {
+    /// The callable
+    call: syn::Expr,
+}
+
+impl AsRef<syn::Expr> for Callable {
+    fn as_ref(&self) -> &syn::Expr {
+        &self.call
+    }
+}
+
+impl From<syn::ExprPath> for Callable {
+    fn from(value: syn::ExprPath) -> Self {
+        Self {
+            call: syn::Expr::Path(value),
+        }
+    }
+}
+
+impl From<syn::ExprClosure> for Callable {
+    fn from(value: syn::ExprClosure) -> Self {
+        Self {
+            call: syn::Expr::Closure(value),
+        }
+    }
+}
+
+impl From<Callable> for syn::Expr {
+    fn from(value: Callable) -> Self {
+        value.call
+    }
+}
+
+impl FromMeta for Callable {
+    fn from_expr(expr: &syn::Expr) -> Result<Self> {
+        match expr {
+            syn::Expr::Path(_) | syn::Expr::Closure(_) => Ok(Self { call: expr.clone() }),
+            _ => Err(Error::unexpected_expr_type(expr)),
+        }
+    }
+}
+
+impl ToTokens for Callable {
+    fn to_tokens(&self, tokens: &mut proc_macro2::TokenStream) {
+        self.call.to_tokens(tokens);
+    }
+}

vendor/darling_core/src/util/flag.rs

@@ -0,0 +1,99 @@
+use proc_macro2::Span;
+use syn::{spanned::Spanned, Meta};
+
+use crate::{FromMeta, Result};
+
+/// A meta-item that can be present as a word - with no value - or absent.
+///
+/// # Defaulting
+/// Like `Option`, `Flag` does not require `#[darling(default)]` to be optional.
+/// If the caller does not include the property, then an absent `Flag` will be included
+/// in the receiver struct.
+///
+/// # Spans
+/// `Flag` keeps the span where its word was seen.
+/// This enables attaching custom error messages to the word, such as in the case of two
+/// conflicting flags being present.
+///
+/// # Example
+/// ```ignore
+/// #[derive(FromMeta)]
+/// #[darling(and_then = Self::not_both)]
+/// struct Demo {
+///     flag_a: Flag,
+///     flag_b: Flag,
+/// }
+///
+/// impl Demo {
+///     fn not_both(self) -> Result<Self> {
+///         if self.flag_a.is_present() && self.flag_b.is_present() {
+///             Err(Error::custom("Cannot set flag_a and flag_b").with_span(&self.flag_b.span()))
+///         } else {
+///             Ok(self)
+///         }
+///     }
+/// }
+/// ```
+///
+/// The above struct would then produce the following error.
+///
+/// ```ignore
+/// #[example(flag_a, flag_b)]
+/// //                ^^^^^^ Cannot set flag_a and flag_b
+/// ```
+#[derive(Debug, Clone, Copy, Default)]
+pub struct Flag(Option<Span>);
+
+impl Flag {
+    /// Creates a new `Flag` which corresponds to the presence of a value.
+    pub fn present() -> Self {
+        Flag(Some(Span::call_site()))
+    }
+
+    /// Check if the flag is present.
+    pub fn is_present(&self) -> bool {
+        self.0.is_some()
+    }
+
+    #[deprecated(since = "0.14.0", note = "Use Flag::is_present")]
+    pub fn is_some(&self) -> bool {
+        self.is_present()
+    }
+
+    /// Get the span of the flag, or [`Span::call_site`] if the flag was not present.
+    pub fn span(&self) -> Span {
+        self.0.unwrap_or_else(Span::call_site)
+    }
+}
+
+impl FromMeta for Flag {
+    fn from_none() -> Option<Self> {
+        Some(Flag(None))
+    }
+
+    fn from_meta(mi: &syn::Meta) -> Result<Self> {
+        if let Meta::Path(p) = mi {
+            Ok(Flag(Some(p.span())))
+        } else {
+            // The implementation for () will produce an error for all non-path meta items;
+            // call it to make sure the span behaviors and error messages are the same.
+            Err(<()>::from_meta(mi).unwrap_err())
+        }
+    }
+}
+
+impl From<Flag> for bool {
+    fn from(flag: Flag) -> Self {
+        flag.is_present()
+    }
+}
+
+impl From<bool> for Flag {
+    fn from(v: bool) -> Self {
+        if v {
+            Flag::present()
+        } else {
+            Flag(None)
+        }
+    }
+}

vendor/darling_core/src/util/ident_string.rs

@@ -0,0 +1,157 @@
+use std::fmt;
+use std::hash::{Hash, Hasher};
+
+use proc_macro2::{Span, TokenStream};
+use quote::ToTokens;
+use syn::{Ident, Meta};
+
+use crate::{FromMeta, Result};
+
+/// A wrapper for an `Ident` which also keeps the value as a string.
+///
+/// This struct can be used to perform string comparisons and operations.
+#[derive(Clone, PartialOrd, Ord)]
+pub struct IdentString {
+    ident: Ident,
+    string: String,
+}
+
+impl IdentString {
+    /// Create a new `IdentString`.
+    pub fn new(ident: Ident) -> Self {
+        IdentString {
+            string: ident.to_string(),
+            ident,
+        }
+    }
+
+    /// Get the ident as a `proc_macro2::Ident`.
+    pub fn as_ident(&self) -> &Ident {
+        &self.ident
+    }
+
+    /// Get the ident as a string.
+    pub fn as_str(&self) -> &str {
+        &self.string
+    }
+
+    /// Get the location of this `Ident` in source.
+    pub fn span(&self) -> Span {
+        self.ident.span()
+    }
+
+    /// Apply some transform to the ident's string representation.
+    ///
+    /// # Panics
+    /// This will panic if the transform produces an invalid ident.
+    pub fn map<F, S>(self, map_fn: F) -> Self
+    where
+        F: FnOnce(String) -> S,
+        S: AsRef<str>,
+    {
+        let span = self.span();
+        let string = map_fn(self.string);
+        Ident::new(string.as_ref(), span).into()
+    }
+}
+
+impl AsRef<Ident> for IdentString {
+    fn as_ref(&self) -> &Ident {
+        self.as_ident()
+    }
+}
+
+impl AsRef<str> for IdentString {
+    fn as_ref(&self) -> &str {
+        self.as_str()
+    }
+}
+
+impl From<Ident> for IdentString {
+    fn from(ident: Ident) -> Self {
+        IdentString::new(ident)
+    }
+}
+
+impl From<IdentString> for Ident {
+    fn from(v: IdentString) -> Ident {
+        v.ident
+    }
+}
+
+impl From<IdentString> for String {
+    fn from(v: IdentString) -> String {
+        v.string
+    }
+}
+
+impl Eq for IdentString {}
+
+impl PartialEq for IdentString {
+    fn eq(&self, rhs: &Self) -> bool {
+        self.ident == rhs.ident
+    }
+}
+
+impl PartialEq<String> for IdentString {
+    fn eq(&self, rhs: &String) -> bool {
+        self.as_str() == rhs
+    }
+}
+
+impl PartialEq<&str> for IdentString {
+    fn eq(&self, rhs: &&str) -> bool {
+        self.as_str() == *rhs
+    }
+}
+
+impl Hash for IdentString {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        self.ident.hash(state);
+    }
+}
+
+impl ToTokens for IdentString {
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        self.ident.to_tokens(tokens);
+    }
+}
+
+impl fmt::Debug for IdentString {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{:?}", self.ident)
+    }
+}
+
+impl fmt::Display for IdentString {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{}", self.ident)
+    }
+}
+
+impl FromMeta for IdentString {
+    fn from_meta(item: &Meta) -> Result<Self> {
+        Ident::from_meta(item).map(IdentString::from)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use syn::parse_quote;
+
+    use super::IdentString;
+
+    #[test]
+    fn convert() {
+        let i_str = IdentString::new(parse_quote!(t));
+        assert_eq!(i_str.as_str(), "t");
+    }
+
+    #[test]
+    fn map_transform() {
+        let i = IdentString::new(parse_quote!(my));
+        let after = i.map(|v| format!("var_{}", v));
+        assert_eq!(after, "var_my");
+        assert_eq!(after, String::from("var_my"));
+    }
+}

vendor/darling_core/src/util/ignored.rs

@@ -0,0 +1,50 @@
+use crate::{
+    usage::{self, UsesLifetimes, UsesTypeParams},
+    FromDeriveInput, FromField, FromGenericParam, FromGenerics, FromMeta, FromTypeParam,
+    FromVariant, Result,
+};
+
+/// An efficient way of discarding data from a syntax element.
+///
+/// All syntax elements will be successfully read into
+/// the `Ignored` struct, with all properties discarded.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Default)]
+pub struct Ignored;
+
+macro_rules! ignored {
+    ($trayt:ident, $method:ident, $syn:path) => {
+        impl $trayt for Ignored {
+            fn $method(_: &$syn) -> Result<Self> {
+                Ok(Ignored)
+            }
+        }
+    };
+}
+
+ignored!(FromGenericParam, from_generic_param, syn::GenericParam);
+ignored!(FromGenerics, from_generics, syn::Generics);
+ignored!(FromTypeParam, from_type_param, syn::TypeParam);
+ignored!(FromMeta, from_meta, syn::Meta);
+ignored!(FromDeriveInput, from_derive_input, syn::DeriveInput);
+ignored!(FromField, from_field, syn::Field);
+ignored!(FromVariant, from_variant, syn::Variant);
+
+impl UsesTypeParams for Ignored {
+    fn uses_type_params<'a>(
+        &self,
+        _opts: &usage::Options,
+        _: &'a usage::IdentSet,
+    ) -> usage::IdentRefSet<'a> {
+        Default::default()
+    }
+}
+
+impl UsesLifetimes for Ignored {
+    fn uses_lifetimes<'a>(
+        &self,
+        _opts: &usage::Options,
+        _: &'a usage::LifetimeSet,
+    ) -> usage::LifetimeRefSet<'a> {
+        Default::default()
+    }
+}

vendor/darling_core/src/util/mod.rs

@@ -0,0 +1,26 @@
+//! Utility types for attribute parsing.
+
+mod callable;
+mod flag;
+mod ident_string;
+mod ignored;
+mod over_ride;
+mod parse_attribute;
+pub mod parse_expr;
+mod path_list;
+mod path_to_string;
+mod shape;
+mod spanned_value;
+mod with_original;
+
+pub use self::callable::Callable;
+pub use self::flag::Flag;
+pub use self::ident_string::IdentString;
+pub use self::ignored::Ignored;
+pub use self::over_ride::Override;
+pub use self::parse_attribute::parse_attribute_to_meta_list;
+pub use self::path_list::PathList;
+pub use self::path_to_string::path_to_string;
+pub use self::shape::{AsShape, Shape, ShapeSet};
+pub use self::spanned_value::SpannedValue;
+pub use self::with_original::WithOriginal;

vendor/darling_core/src/util/over_ride.rs

@@ -0,0 +1,163 @@
+use std::fmt;
+
+use syn::Lit;
+
+use crate::ast::NestedMeta;
+use crate::{FromMeta, Result};
+
+use self::Override::*;
+
+/// A value which can inherit a default value or have an explicit value specified.
+///
+/// # Usage
+/// This type is meant for attributes like `default` in `darling`, which can take the following forms:
+///
+/// * `#[darling(default)]`
+/// * `#[darling(default="path::to::fn")]`
+///
+/// In a struct collecting input for this attribute, that would be written as:
+///
+/// ```rust,ignore
+/// use darling::{util::Override, FromField};
+/// #[derive(FromField)]
+/// #[darling(attributes(darling))]
+/// pub struct Options {
+///    default: Option<Override<syn::Path>>,
+/// }
+///
+/// impl Options {
+///     fn hydrate(self) -> Option<syn::Path> {
+///         self.default.map(|ov| ov.unwrap_or(syn::parse_path("::Default::default").unwrap()))
+///     }
+/// }
+/// ```
+///
+/// The `word` format (with no associated value), would produce `Override::Inherit`, while a list
+/// or value format would produce `Override::Explicit`.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum Override<T> {
+    /// Inherit the eventual value from an external source.
+    Inherit,
+
+    /// Explicitly set the value.
+    Explicit(T),
+}
+
+impl<T> Override<T> {
+    /// Converts from `Override<T>` to `Override<&T>`.
+    ///
+    /// Produces a new `Override`, containing a reference into the original, leaving the original in place.
+    pub fn as_ref(&self) -> Override<&T> {
+        match *self {
+            Inherit => Inherit,
+            Explicit(ref val) => Explicit(val),
+        }
+    }
+
+    /// Converts from `Override<T>` to `Override<&mut T>`.
+    ///
+    /// Produces a new `Override`, containing a mutable reference into the original.
+    pub fn as_mut(&mut self) -> Override<&mut T> {
+        match *self {
+            Inherit => Inherit,
+            Explicit(ref mut val) => Explicit(val),
+        }
+    }
+
+    /// Returns `true` if the override is an `Explicit` value.
+    pub fn is_explicit(&self) -> bool {
+        match *self {
+            Inherit => false,
+            Explicit(_) => true,
+        }
+    }
+
+    /// Converts from `Override<T>` to `Option<T>`.
+    pub fn explicit(self) -> Option<T> {
+        match self {
+            Inherit => None,
+            Explicit(val) => Some(val),
+        }
+    }
+
+    /// Unwraps an override, yielding the content of an `Explicit`. Otherwise, it returns `optb`.
+    pub fn unwrap_or(self, optb: T) -> T {
+        match self {
+            Inherit => optb,
+            Explicit(val) => val,
+        }
+    }
+
+    /// Unwraps an override, yielding the content of an `Explicit`. Otherwise, it calls `op`.
+    pub fn unwrap_or_else<F>(self, op: F) -> T
+    where
+        F: FnOnce() -> T,
+    {
+        match self {
+            Inherit => op(),
+            Explicit(val) => val,
+        }
+    }
+}
+
+impl<T: Default> Override<T> {
+    /// Returns the contained value or the default value of `T`.
+    pub fn unwrap_or_default(self) -> T {
+        match self {
+            Inherit => Default::default(),
+            Explicit(val) => val,
+        }
+    }
+}
+
+impl<T> Default for Override<T> {
+    fn default() -> Self {
+        Inherit
+    }
+}
+
+impl<T> From<Option<T>> for Override<T> {
+    fn from(v: Option<T>) -> Self {
+        match v {
+            None => Inherit,
+            Some(val) => Explicit(val),
+        }
+    }
+}
+
+impl<T: fmt::Display> fmt::Display for Override<T> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match *self {
+            Inherit => write!(f, "Inherit"),
+            Explicit(ref val) => write!(f, "Explicit `{}`", val),
+        }
+    }
+}
+
+/// Parses a `Meta`. A bare word will produce `Override::Inherit`, while
+/// any value will be forwarded to `T::from_meta`.
+impl<T: FromMeta> FromMeta for Override<T> {
+    fn from_word() -> Result<Self> {
+        Ok(Inherit)
+    }
+
+    fn from_list(items: &[NestedMeta]) -> Result<Self> {
+        Ok(Explicit(FromMeta::from_list(items)?))
+    }
+
+    fn from_value(lit: &Lit) -> Result<Self> {
+        Ok(Explicit(FromMeta::from_value(lit)?))
+    }
+
+    fn from_char(value: char) -> Result<Self> {
+        Ok(Explicit(FromMeta::from_char(value)?))
+    }
+
+    fn from_string(value: &str) -> Result<Self> {
+        Ok(Explicit(FromMeta::from_string(value)?))
+    }
+
+    fn from_bool(value: bool) -> Result<Self> {
+        Ok(Explicit(FromMeta::from_bool(value)?))
+    }
+}

vendor/darling_core/src/util/parse_attribute.rs

@@ -0,0 +1,86 @@
+use crate::{Error, Result};
+use std::fmt;
+use syn::punctuated::Pair;
+use syn::spanned::Spanned;
+use syn::{token, Attribute, Meta, MetaList, Path};
+
+/// Try to parse an attribute into a meta list. Path-type meta values are accepted and returned
+/// as empty lists with their passed-in path. Name-value meta values and non-meta attributes
+/// will cause errors to be returned.
+pub fn parse_attribute_to_meta_list(attr: &Attribute) -> Result<MetaList> {
+    match &attr.meta {
+        Meta::List(list) => Ok(list.clone()),
+        Meta::NameValue(nv) => Err(Error::custom(format!(
+            "Name-value arguments are not supported. Use #[{}(...)]",
+            DisplayPath(&nv.path)
+        ))
+        .with_span(&nv)),
+        Meta::Path(path) => Ok(MetaList {
+            path: path.clone(),
+            delimiter: syn::MacroDelimiter::Paren(token::Paren {
+                span: {
+                    let mut group = proc_macro2::Group::new(
+                        proc_macro2::Delimiter::None,
+                        proc_macro2::TokenStream::new(),
+                    );
+                    group.set_span(attr.span());
+                    group.delim_span()
+                },
+            }),
+            tokens: Default::default(),
+        }),
+    }
+}
+
+struct DisplayPath<'a>(&'a Path);
+
+impl fmt::Display for DisplayPath<'_> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let path = self.0;
+        if path.leading_colon.is_some() {
+            write!(f, "::")?;
+        }
+        for segment in path.segments.pairs() {
+            match segment {
+                Pair::Punctuated(segment, _) => write!(f, "{}::", segment.ident)?,
+                Pair::End(segment) => segment.ident.fmt(f)?,
+            }
+        }
+
+        Ok(())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::parse_attribute_to_meta_list;
+    use crate::ast::NestedMeta;
+    use syn::spanned::Spanned;
+    use syn::{parse_quote, Ident};
+
+    #[test]
+    fn parse_list() {
+        let meta = parse_attribute_to_meta_list(&parse_quote!(#[bar(baz = 4)])).unwrap();
+        let nested_meta = NestedMeta::parse_meta_list(meta.tokens).unwrap();
+        assert_eq!(nested_meta.len(), 1);
+    }
+
+    #[test]
+    fn parse_path_returns_empty_list() {
+        let meta = parse_attribute_to_meta_list(&parse_quote!(#[bar])).unwrap();
+        let nested_meta = NestedMeta::parse_meta_list(meta.tokens).unwrap();
+        assert!(meta.path.is_ident(&Ident::new("bar", meta.path.span())));
+        assert!(nested_meta.is_empty());
+    }
+
+    #[test]
+    fn parse_name_value_returns_error() {
+        parse_attribute_to_meta_list(&parse_quote!(#[bar = 4])).unwrap_err();
+    }
+
+    #[test]
+    fn parse_name_value_error_includes_example() {
+        let err = parse_attribute_to_meta_list(&parse_quote!(#[bar = 4])).unwrap_err();
+        assert!(err.to_string().contains("#[bar(...)]"));
+    }
+}

vendor/darling_core/src/util/parse_expr.rs

@@ -0,0 +1,86 @@
+//! Functions to use with `#[darling(with = "...")]` that control how quoted values
+//! in [`Meta`] instances are parsed into [`Expr`] fields.
+//!
+//! Version 1 of syn did not permit expressions on the right-hand side of the `=` in a
+//! [`MetaNameValue`](syn::MetaNameValue), so darling accepted string literals and then
+//! parsed their contents as expressions.
+//! Passing a string literal in this version would have required the use of a raw string
+//! to add quotation marks inside the literal.
+//!
+//! Version 2 of syn removes the requirement that the right-hand side be a literal.
+//! For most types, such as [`Path`](syn::Path), the [`FromMeta`] impl can accept the
+//! version without quotation marks without causing ambiguity; a path cannot start and
+//! end with quotation marks, so removal is automatic.
+//!
+//! [`Expr`] is the one type where this ambiguity is new and unavoidable. To address this,
+//! this module provides different functions for different expected behaviors.
+
+use syn::{Expr, Meta};
+
+use crate::{Error, FromMeta};
+
+/// Parse a [`Meta`] to an [`Expr`]; if the value is a string literal, the emitted
+/// expression will be a string literal.
+pub fn preserve_str_literal(meta: &Meta) -> crate::Result<Expr> {
+    match meta {
+        Meta::Path(_) => Err(Error::unsupported_format("path").with_span(meta)),
+        Meta::List(_) => Err(Error::unsupported_format("list").with_span(meta)),
+        Meta::NameValue(nv) => Ok(nv.value.clone()),
+    }
+}
+
+/// Parse a [`Meta`] to an [`Expr`]; if the value is a string literal, the string's
+/// contents will be parsed as an expression and emitted.
+pub fn parse_str_literal(meta: &Meta) -> crate::Result<Expr> {
+    match meta {
+        Meta::Path(_) => Err(Error::unsupported_format("path").with_span(meta)),
+        Meta::List(_) => Err(Error::unsupported_format("list").with_span(meta)),
+        Meta::NameValue(nv) => {
+            if let Expr::Lit(expr_lit) = &nv.value {
+                Expr::from_value(&expr_lit.lit)
+            } else {
+                Ok(nv.value.clone())
+            }
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use syn::parse_quote;
+
+    use super::*;
+
+    macro_rules! meta {
+        ($body:expr) => {
+            {
+                let attr: ::syn::Attribute = ::syn::parse_quote!(#[ignore = $body]);
+                attr.meta
+            }
+        };
+    }
+
+    #[test]
+    fn preserve_str() {
+        assert_eq!(
+            preserve_str_literal(&meta!("World")).unwrap(),
+            parse_quote!("World")
+        );
+    }
+
+    #[test]
+    fn preserve_binary_exp() {
+        assert_eq!(
+            preserve_str_literal(&meta!("World" + 5)).unwrap(),
+            parse_quote!("World" + 5)
+        )
+    }
+
+    #[test]
+    fn parse_ident() {
+        assert_eq!(
+            parse_str_literal(&meta!("world")).unwrap(),
+            parse_quote!(world)
+        )
+    }
+}

vendor/darling_core/src/util/path_list.rs

@@ -0,0 +1,105 @@
+use std::ops::Deref;
+
+use syn::{Meta, Path};
+
+use crate::ast::NestedMeta;
+use crate::{Error, FromMeta, Result};
+
+use super::path_to_string;
+
+/// A list of `syn::Path` instances. This type is used to extract a list of paths from an
+/// attribute.
+///
+/// # Usage
+/// An `PathList` field on a struct implementing `FromMeta` will turn `#[builder(derive(serde::Debug, Clone))]` into:
+///
+/// ```rust,ignore
+/// StructOptions {
+///     derive: PathList(vec![syn::Path::new("serde::Debug"), syn::Path::new("Clone")])
+/// }
+/// ```
+#[derive(Debug, Default, Clone, PartialEq, Eq)]
+pub struct PathList(Vec<Path>);
+
+impl PathList {
+    /// Create a new list.
+    pub fn new<T: Into<Path>>(vals: Vec<T>) -> Self {
+        PathList(vals.into_iter().map(T::into).collect())
+    }
+
+    /// Create a new `Vec` containing the string representation of each path.
+    pub fn to_strings(&self) -> Vec<String> {
+        self.0.iter().map(path_to_string).collect()
+    }
+}
+
+impl Deref for PathList {
+    type Target = Vec<Path>;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl From<Vec<Path>> for PathList {
+    fn from(v: Vec<Path>) -> Self {
+        PathList(v)
+    }
+}
+
+impl FromMeta for PathList {
+    fn from_list(v: &[NestedMeta]) -> Result<Self> {
+        let mut paths = Vec::with_capacity(v.len());
+        for nmi in v {
+            if let NestedMeta::Meta(Meta::Path(ref path)) = *nmi {
+                paths.push(path.clone());
+            } else {
+                return Err(Error::unexpected_type("non-word").with_span(nmi));
+            }
+        }
+
+        Ok(PathList(paths))
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::PathList;
+    use crate::FromMeta;
+    use proc_macro2::TokenStream;
+    use quote::quote;
+    use syn::{parse_quote, Attribute, Meta};
+
+    /// parse a string as a syn::Meta instance.
+    fn pm(tokens: TokenStream) -> ::std::result::Result<Meta, String> {
+        let attribute: Attribute = parse_quote!(#[#tokens]);
+        Ok(attribute.meta)
+    }
+
+    fn fm<T: FromMeta>(tokens: TokenStream) -> T {
+        FromMeta::from_meta(&pm(tokens).expect("Tests should pass well-formed input"))
+            .expect("Tests should pass valid input")
+    }
+
+    #[test]
+    fn succeeds() {
+        let paths = fm::<PathList>(quote!(ignore(Debug, Clone, Eq)));
+        assert_eq!(
+            paths.to_strings(),
+            vec![
+                String::from("Debug"),
+                String::from("Clone"),
+                String::from("Eq")
+            ]
+        );
+    }
+
+    /// Check that the parser rejects non-word members of the list, and that the error
+    /// has an associated span.
+    #[test]
+    fn fails_non_word() {
+        let input = PathList::from_meta(&pm(quote!(ignore(Debug, Clone = false))).unwrap());
+        let err = input.unwrap_err();
+        assert!(err.has_span());
+    }
+}

vendor/darling_core/src/util/path_to_string.rs

@@ -0,0 +1,36 @@
+/// Transform Rust paths to a readable and comparable string.
+///
+/// # Limitations
+/// * Leading colons are ignored.
+/// * Angle brackets and `as` elements are ignored.
+///
+/// # Example
+/// ```rust
+/// # use darling_core::util::path_to_string;
+/// # use syn::parse_quote;
+/// assert_eq!(path_to_string(&parse_quote!(a::b)), "a::b");
+/// ```
+pub fn path_to_string(path: &syn::Path) -> String {
+    path.segments
+        .iter()
+        .map(|s| s.ident.to_string())
+        .collect::<Vec<String>>()
+        .join("::")
+}
+
+#[cfg(test)]
+mod tests {
+    use syn::parse_quote;
+
+    use super::path_to_string;
+
+    #[test]
+    fn simple_ident() {
+        assert_eq!(path_to_string(&parse_quote!(a)), "a");
+    }
+
+    #[test]
+    fn simple_path() {
+        assert_eq!(path_to_string(&parse_quote!(a::b)), "a::b");
+    }
+}

vendor/darling_core/src/util/shape.rs

@@ -0,0 +1,285 @@
+use std::{fmt, iter::FromIterator};
+
+use crate::ast;
+
+/// Get the "shape" of a fields container, such as a struct or variant.
+pub trait AsShape {
+    /// Get the "shape" of a fields container.
+    fn as_shape(&self) -> Shape;
+}
+
+impl<T> AsShape for ast::Fields<T> {
+    fn as_shape(&self) -> Shape {
+        match self.style {
+            ast::Style::Tuple if self.fields.len() == 1 => Shape::Newtype,
+            ast::Style::Tuple => Shape::Tuple,
+            ast::Style::Struct => Shape::Named,
+            ast::Style::Unit => Shape::Unit,
+        }
+    }
+}
+
+impl AsShape for syn::Fields {
+    fn as_shape(&self) -> Shape {
+        match self {
+            syn::Fields::Named(fields) => fields.as_shape(),
+            syn::Fields::Unnamed(fields) => fields.as_shape(),
+            syn::Fields::Unit => Shape::Unit,
+        }
+    }
+}
+
+impl AsShape for syn::FieldsNamed {
+    fn as_shape(&self) -> Shape {
+        Shape::Named
+    }
+}
+
+impl AsShape for syn::FieldsUnnamed {
+    fn as_shape(&self) -> Shape {
+        if self.unnamed.len() == 1 {
+            Shape::Newtype
+        } else {
+            Shape::Tuple
+        }
+    }
+}
+
+impl AsShape for syn::DataStruct {
+    fn as_shape(&self) -> Shape {
+        self.fields.as_shape()
+    }
+}
+
+impl AsShape for syn::Variant {
+    fn as_shape(&self) -> Shape {
+        self.fields.as_shape()
+    }
+}
+
+/// Description of how fields in a struct or variant are syntactically laid out.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum Shape {
+    /// A set of named fields, e.g. `{ field: String }`.
+    Named,
+    /// A list of unnamed fields, e.g. `(String, u64)`.
+    Tuple,
+    /// No fields, e.g. `struct Example;`
+    Unit,
+    /// A special case of [`Tuple`](Shape#variant.Tuple) with exactly one field, e.g. `(String)`.
+    Newtype,
+}
+
+impl Shape {
+    pub fn description(&self) -> &'static str {
+        match self {
+            Shape::Named => "named fields",
+            Shape::Tuple => "unnamed fields",
+            Shape::Unit => "no fields",
+            Shape::Newtype => "one unnamed field",
+        }
+    }
+}
+
+impl fmt::Display for Shape {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{}", self.description())
+    }
+}
+
+impl AsShape for Shape {
+    fn as_shape(&self) -> Shape {
+        *self
+    }
+}
+
+/// A set of [`Shape`] values, which correctly handles the relationship between
+/// [newtype](Shape#variant.Newtype) and [tuple](Shape#variant.Tuple) shapes.
+///
+/// # Example
+/// ```rust
+/// # use darling_core::util::{Shape, ShapeSet};
+/// let shape_set = ShapeSet::new(vec![Shape::Tuple]);
+///
+/// // This is correct, because all newtypes are single-field tuples.
+/// assert!(shape_set.contains(&Shape::Newtype));
+/// ```
+#[derive(Debug, Clone, Default)]
+pub struct ShapeSet {
+    newtype: bool,
+    named: bool,
+    tuple: bool,
+    unit: bool,
+}
+
+impl ShapeSet {
+    /// Create a new `ShapeSet` which includes the specified items.
+    ///
+    /// # Exampe
+    /// ```rust
+    /// # use darling_core::util::{Shape, ShapeSet};
+    /// let shape_set = ShapeSet::new(vec![Shape::Named, Shape::Newtype]);
+    /// assert!(shape_set.contains(&Shape::Newtype));
+    /// ```
+    pub fn new(items: impl IntoIterator<Item = Shape>) -> Self {
+        items.into_iter().collect()
+    }
+
+    /// Insert all possible shapes into the set.
+    ///
+    /// This is equivalent to calling [`insert`](ShapeSet#method.insert) with every value of [`Shape`].
+    ///
+    /// # Example
+    /// ```rust
+    /// # use darling_core::util::{Shape, ShapeSet};
+    /// let mut shape_set = ShapeSet::default();
+    /// shape_set.insert_all();
+    /// assert!(shape_set.contains(&Shape::Named));
+    /// ```
+    pub fn insert_all(&mut self) {
+        self.insert(Shape::Named);
+        self.insert(Shape::Newtype);
+        self.insert(Shape::Tuple);
+        self.insert(Shape::Unit);
+    }
+
+    /// Insert a shape into the set, so that the set will match that shape
+    pub fn insert(&mut self, shape: Shape) {
+        match shape {
+            Shape::Named => self.named = true,
+            Shape::Tuple => self.tuple = true,
+            Shape::Unit => self.unit = true,
+            Shape::Newtype => self.newtype = true,
+        }
+    }
+
+    /// Whether this set is empty.
+    pub fn is_empty(&self) -> bool {
+        !self.named && !self.newtype && !self.tuple && !self.unit
+    }
+
+    fn contains_shape(&self, shape: Shape) -> bool {
+        match shape {
+            Shape::Named => self.named,
+            Shape::Tuple => self.tuple,
+            Shape::Unit => self.unit,
+            Shape::Newtype => self.newtype || self.tuple,
+        }
+    }
+
+    /// Check if a fields container's shape is in this set.
+    pub fn contains(&self, fields: &impl AsShape) -> bool {
+        self.contains_shape(fields.as_shape())
+    }
+
+    /// Check if a field container's shape is in this set of shapes, and produce
+    /// an [`Error`](crate::Error) if it does not.
+    pub fn check(&self, fields: &impl AsShape) -> crate::Result<()> {
+        let shape = fields.as_shape();
+
+        if self.contains_shape(shape) {
+            Ok(())
+        } else {
+            Err(crate::Error::unsupported_shape_with_expected(
+                shape.description(),
+                self,
+            ))
+        }
+    }
+
+    fn to_vec(&self) -> Vec<Shape> {
+        let mut shapes = Vec::with_capacity(3);
+
+        if self.named {
+            shapes.push(Shape::Named);
+        }
+
+        if self.tuple || self.newtype {
+            shapes.push(if self.tuple {
+                Shape::Tuple
+            } else {
+                Shape::Newtype
+            });
+        }
+
+        if self.unit {
+            shapes.push(Shape::Unit)
+        }
+
+        shapes
+    }
+}
+
+impl fmt::Display for ShapeSet {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let shapes = self.to_vec();
+
+        match shapes.len() {
+            0 => write!(f, "nothing"),
+            1 => write!(f, "{}", shapes[0]),
+            2 => write!(f, "{} or {}", shapes[0], shapes[1]),
+            3 => write!(f, "{}, {}, or {}", shapes[0], shapes[1], shapes[2]),
+            _ => unreachable!(),
+        }
+    }
+}
+
+impl FromIterator<Shape> for ShapeSet {
+    fn from_iter<T: IntoIterator<Item = Shape>>(iter: T) -> Self {
+        let mut output = ShapeSet::default();
+        for shape in iter.into_iter() {
+            output.insert(shape);
+        }
+
+        output
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use syn::parse_quote;
+
+    use super::*;
+
+    #[test]
+    fn any_accepts_anything() {
+        let mut filter = ShapeSet::default();
+        filter.insert_all();
+        let unit_struct: syn::DeriveInput = syn::parse_quote! {
+            struct Example;
+        };
+        if let syn::Data::Struct(data) = unit_struct.data {
+            assert!(filter.contains(&data));
+        } else {
+            panic!("Struct not parsed as struct");
+        };
+    }
+
+    #[test]
+    fn tuple_accepts_newtype() {
+        let filter = ShapeSet::new(vec![Shape::Tuple]);
+        let newtype_struct: syn::DeriveInput = parse_quote! {
+            struct Example(String);
+        };
+
+        if let syn::Data::Struct(data) = newtype_struct.data {
+            assert!(filter.contains(&data));
+        } else {
+            panic!("Struct not parsed as struct");
+        };
+    }
+
+    #[test]
+    fn newtype_rejects_tuple() {
+        let filter = ShapeSet::new(vec![Shape::Newtype]);
+        let tuple_struct: syn::DeriveInput = parse_quote! {
+            struct Example(String, u64);
+        };
+
+        if let syn::Data::Struct(data) = tuple_struct.data {
+            assert!(!filter.contains(&data));
+        } else {
+            panic!("Struct not parsed as struct");
+        };
+    }
+}

vendor/darling_core/src/util/spanned_value.rs

@@ -0,0 +1,145 @@
+use proc_macro2::Span;
+use std::ops::{Deref, DerefMut};
+use syn::spanned::Spanned;
+
+use crate::{
+    FromDeriveInput, FromField, FromGenericParam, FromGenerics, FromMeta, FromTypeParam,
+    FromVariant, Result,
+};
+
+/// A value and an associated position in source code. The main use case for this is
+/// to preserve position information to emit warnings from proc macros. You can use
+/// a `SpannedValue<T>` as a field in any struct that implements or derives any of
+/// `darling`'s core traits.
+///
+/// To access the underlying value, use the struct's `Deref` implementation.
+///
+/// # Defaulting
+/// This type is meant to be used in conjunction with attribute-extracted options,
+/// but the user may not always explicitly set those options in their source code.
+/// In this case, using `Default::default()` will create an instance which points
+/// to `Span::call_site()`.
+#[derive(Debug, Clone, Copy)]
+pub struct SpannedValue<T> {
+    value: T,
+    span: Span,
+}
+
+impl<T> SpannedValue<T> {
+    pub fn new(value: T, span: Span) -> Self {
+        SpannedValue { value, span }
+    }
+
+    /// Get the source code location referenced by this struct.
+    pub fn span(&self) -> Span {
+        self.span
+    }
+
+    /// Apply a mapping function to a reference to the spanned value.
+    pub fn map_ref<U>(&self, map_fn: impl FnOnce(&T) -> U) -> SpannedValue<U> {
+        SpannedValue::new(map_fn(&self.value), self.span)
+    }
+}
+
+impl<T: Default> Default for SpannedValue<T> {
+    fn default() -> Self {
+        SpannedValue::new(Default::default(), Span::call_site())
+    }
+}
+
+impl<T> Deref for SpannedValue<T> {
+    type Target = T;
+
+    fn deref(&self) -> &T {
+        &self.value
+    }
+}
+
+impl<T> DerefMut for SpannedValue<T> {
+    fn deref_mut(&mut self) -> &mut T {
+        &mut self.value
+    }
+}
+
+impl<T> AsRef<T> for SpannedValue<T> {
+    fn as_ref(&self) -> &T {
+        &self.value
+    }
+}
+
+macro_rules! spanned {
+    ($trayt:ident, $method:ident, $syn:path) => {
+        impl<T: $trayt> $trayt for SpannedValue<T> {
+            fn $method(value: &$syn) -> Result<Self> {
+                Ok(SpannedValue::new(
+                    $trayt::$method(value).map_err(|e| e.with_span(value))?,
+                    value.span(),
+                ))
+            }
+        }
+    };
+}
+
+impl<T: FromMeta> FromMeta for SpannedValue<T> {
+    fn from_meta(item: &syn::Meta) -> Result<Self> {
+        let value = T::from_meta(item).map_err(|e| e.with_span(item))?;
+        let span = match item {
+            // Example: `#[darling(skip)]` as SpannedValue<bool>
+            // should have the span pointing to the word `skip`.
+            syn::Meta::Path(path) => path.span(),
+            // Example: `#[darling(attributes(Value))]` as a SpannedValue<Vec<String>>
+            // should have the span pointing to the list contents.
+            syn::Meta::List(list) => list.tokens.span(),
+            // Example: `#[darling(skip = true)]` as SpannedValue<bool>
+            // should have the span pointing to the word `true`.
+            syn::Meta::NameValue(nv) => nv.value.span(),
+        };
+
+        Ok(Self::new(value, span))
+    }
+
+    fn from_nested_meta(item: &crate::ast::NestedMeta) -> Result<Self> {
+        T::from_nested_meta(item)
+            .map(|value| Self::new(value, item.span()))
+            .map_err(|e| e.with_span(item))
+    }
+
+    fn from_value(literal: &syn::Lit) -> Result<Self> {
+        T::from_value(literal)
+            .map(|value| Self::new(value, literal.span()))
+            .map_err(|e| e.with_span(literal))
+    }
+
+    fn from_expr(expr: &syn::Expr) -> Result<Self> {
+        T::from_expr(expr)
+            .map(|value| Self::new(value, expr.span()))
+            .map_err(|e| e.with_span(expr))
+    }
+}
+
+spanned!(FromGenericParam, from_generic_param, syn::GenericParam);
+spanned!(FromGenerics, from_generics, syn::Generics);
+spanned!(FromTypeParam, from_type_param, syn::TypeParam);
+spanned!(FromDeriveInput, from_derive_input, syn::DeriveInput);
+spanned!(FromField, from_field, syn::Field);
+spanned!(FromVariant, from_variant, syn::Variant);
+
+impl<T: Spanned> From<T> for SpannedValue<T> {
+    fn from(value: T) -> Self {
+        let span = value.span();
+        SpannedValue::new(value, span)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use proc_macro2::Span;
+
+    /// Make sure that `SpannedValue` can be seamlessly used as its underlying type.
+    #[test]
+    fn deref() {
+        let test = SpannedValue::new("hello", Span::call_site());
+        assert_eq!("hello", test.trim());
+    }
+}

vendor/darling_core/src/util/with_original.rs

@@ -0,0 +1,35 @@
+use crate::{
+    FromDeriveInput, FromField, FromGenericParam, FromGenerics, FromMeta, FromTypeParam,
+    FromVariant, Result,
+};
+
+/// A container to parse some syntax and retain access to the original.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct WithOriginal<T, O> {
+    pub parsed: T,
+    pub original: O,
+}
+
+impl<T, O> WithOriginal<T, O> {
+    pub fn new(parsed: T, original: O) -> Self {
+        WithOriginal { parsed, original }
+    }
+}
+
+macro_rules! with_original {
+    ($trayt:ident, $func:ident, $syn:path) => {
+        impl<T: $trayt> $trayt for WithOriginal<T, $syn> {
+            fn $func(value: &$syn) -> Result<Self> {
+                Ok(WithOriginal::new($trayt::$func(value)?, value.clone()))
+            }
+        }
+    };
+}
+
+with_original!(FromDeriveInput, from_derive_input, syn::DeriveInput);
+with_original!(FromField, from_field, syn::Field);
+with_original!(FromGenerics, from_generics, syn::Generics);
+with_original!(FromGenericParam, from_generic_param, syn::GenericParam);
+with_original!(FromMeta, from_meta, syn::Meta);
+with_original!(FromTypeParam, from_type_param, syn::TypeParam);
+with_original!(FromVariant, from_variant, syn::Variant);