Initial vendor packages

Signed-off-by: Valentin Popov <valentin@popov.link>

1 files changed, 467 insertions, 0 deletions

diff --git a/vendor/syn/src/error.rs b/vendor/syn/src/error.rs
new file mode 100644
index 0000000..71247cd
--- /dev/null
+++ b/vendor/syn/src/error.rs
@@ -0,0 +1,467 @@
+#[cfg(feature = "parsing")]
+use crate::buffer::Cursor;
+use crate::thread::ThreadBound;
+use proc_macro2::{
+    Delimiter, Group, Ident, LexError, Literal, Punct, Spacing, Span, TokenStream, TokenTree,
+};
+#[cfg(feature = "printing")]
+use quote::ToTokens;
+use std::fmt::{self, Debug, Display};
+use std::slice;
+use std::vec;
+
+/// The result of a Syn parser.
+pub type Result<T> = std::result::Result<T, Error>;
+
+/// Error returned when a Syn parser cannot parse the input tokens.
+///
+/// # Error reporting in proc macros
+///
+/// The correct way to report errors back to the compiler from a procedural
+/// macro is by emitting an appropriately spanned invocation of
+/// [`compile_error!`] in the generated code. This produces a better diagnostic
+/// message than simply panicking the macro.
+///
+/// [`compile_error!`]: std::compile_error!
+///
+/// When parsing macro input, the [`parse_macro_input!`] macro handles the
+/// conversion to `compile_error!` automatically.
+///
+/// [`parse_macro_input!`]: crate::parse_macro_input!
+///
+/// ```
+/// # extern crate proc_macro;
+/// #
+/// use proc_macro::TokenStream;
+/// use syn::parse::{Parse, ParseStream, Result};
+/// use syn::{parse_macro_input, ItemFn};
+///
+/// # const IGNORE: &str = stringify! {
+/// #[proc_macro_attribute]
+/// # };
+/// pub fn my_attr(args: TokenStream, input: TokenStream) -> TokenStream {
+///     let args = parse_macro_input!(args as MyAttrArgs);
+///     let input = parse_macro_input!(input as ItemFn);
+///
+///     /* ... */
+///     # TokenStream::new()
+/// }
+///
+/// struct MyAttrArgs {
+///     # _k: [(); { stringify! {
+///     ...
+///     # }; 0 }]
+/// }
+///
+/// impl Parse for MyAttrArgs {
+///     fn parse(input: ParseStream) -> Result<Self> {
+///         # stringify! {
+///         ...
+///         # };
+///         # unimplemented!()
+///     }
+/// }
+/// ```
+///
+/// For errors that arise later than the initial parsing stage, the
+/// [`.to_compile_error()`] or [`.into_compile_error()`] methods can be used to
+/// perform an explicit conversion to `compile_error!`.
+///
+/// [`.to_compile_error()`]: Error::to_compile_error
+/// [`.into_compile_error()`]: Error::into_compile_error
+///
+/// ```
+/// # extern crate proc_macro;
+/// #
+/// # use proc_macro::TokenStream;
+/// # use syn::{parse_macro_input, DeriveInput};
+/// #
+/// # const IGNORE: &str = stringify! {
+/// #[proc_macro_derive(MyDerive)]
+/// # };
+/// pub fn my_derive(input: TokenStream) -> TokenStream {
+///     let input = parse_macro_input!(input as DeriveInput);
+///
+///     // fn(DeriveInput) -> syn::Result<proc_macro2::TokenStream>
+///     expand::my_derive(input)
+///         .unwrap_or_else(syn::Error::into_compile_error)
+///         .into()
+/// }
+/// #
+/// # mod expand {
+/// #     use proc_macro2::TokenStream;
+/// #     use syn::{DeriveInput, Result};
+/// #
+/// #     pub fn my_derive(input: DeriveInput) -> Result<TokenStream> {
+/// #         unimplemented!()
+/// #     }
+/// # }
+/// ```
+pub struct Error {
+    messages: Vec<ErrorMessage>,
+}
+
+struct ErrorMessage {
+    // Span is implemented as an index into a thread-local interner to keep the
+    // size small. It is not safe to access from a different thread. We want
+    // errors to be Send and Sync to play nicely with ecosystem crates for error
+    // handling, so pin the span we're given to its original thread and assume
+    // it is Span::call_site if accessed from any other thread.
+    span: ThreadBound<SpanRange>,
+    message: String,
+}
+
+// Cannot use std::ops::Range<Span> because that does not implement Copy,
+// whereas ThreadBound<T> requires a Copy impl as a way to ensure no Drop impls
+// are involved.
+struct SpanRange {
+    start: Span,
+    end: Span,
+}
+
+#[cfg(test)]
+struct _Test
+where
+    Error: Send + Sync;
+
+impl Error {
+    /// Usually the [`ParseStream::error`] method will be used instead, which
+    /// automatically uses the correct span from the current position of the
+    /// parse stream.
+    ///
+    /// Use `Error::new` when the error needs to be triggered on some span other
+    /// than where the parse stream is currently positioned.
+    ///
+    /// [`ParseStream::error`]: crate::parse::ParseBuffer::error
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use syn::{Error, Ident, LitStr, Result, Token};
+    /// use syn::parse::ParseStream;
+    ///
+    /// // Parses input that looks like `name = "string"` where the key must be
+    /// // the identifier `name` and the value may be any string literal.
+    /// // Returns the string literal.
+    /// fn parse_name(input: ParseStream) -> Result<LitStr> {
+    ///     let name_token: Ident = input.parse()?;
+    ///     if name_token != "name" {
+    ///         // Trigger an error not on the current position of the stream,
+    ///         // but on the position of the unexpected identifier.
+    ///         return Err(Error::new(name_token.span(), "expected `name`"));
+    ///     }
+    ///     input.parse::<Token![=]>()?;
+    ///     let s: LitStr = input.parse()?;
+    ///     Ok(s)
+    /// }
+    /// ```
+    pub fn new<T: Display>(span: Span, message: T) -> Self {
+        return new(span, message.to_string());
+
+        fn new(span: Span, message: String) -> Error {
+            Error {
+                messages: vec![ErrorMessage {
+                    span: ThreadBound::new(SpanRange {
+                        start: span,
+                        end: span,
+                    }),
+                    message,
+                }],
+            }
+        }
+    }
+
+    /// Creates an error with the specified message spanning the given syntax
+    /// tree node.
+    ///
+    /// Unlike the `Error::new` constructor, this constructor takes an argument
+    /// `tokens` which is a syntax tree node. This allows the resulting `Error`
+    /// to attempt to span all tokens inside of `tokens`. While you would
+    /// typically be able to use the `Spanned` trait with the above `Error::new`
+    /// constructor, implementation limitations today mean that
+    /// `Error::new_spanned` may provide a higher-quality error message on
+    /// stable Rust.
+    ///
+    /// When in doubt it's recommended to stick to `Error::new` (or
+    /// `ParseStream::error`)!
+    #[cfg(feature = "printing")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    pub fn new_spanned<T: ToTokens, U: Display>(tokens: T, message: U) -> Self {
+        return new_spanned(tokens.into_token_stream(), message.to_string());
+
+        fn new_spanned(tokens: TokenStream, message: String) -> Error {
+            let mut iter = tokens.into_iter();
+            let start = iter.next().map_or_else(Span::call_site, |t| t.span());
+            let end = iter.last().map_or(start, |t| t.span());
+            Error {
+                messages: vec![ErrorMessage {
+                    span: ThreadBound::new(SpanRange { start, end }),
+                    message,
+                }],
+            }
+        }
+    }
+
+    /// The source location of the error.
+    ///
+    /// Spans are not thread-safe so this function returns `Span::call_site()`
+    /// if called from a different thread than the one on which the `Error` was
+    /// originally created.
+    pub fn span(&self) -> Span {
+        let SpanRange { start, end } = match self.messages[0].span.get() {
+            Some(span) => *span,
+            None => return Span::call_site(),
+        };
+        start.join(end).unwrap_or(start)
+    }
+
+    /// Render the error as an invocation of [`compile_error!`].
+    ///
+    /// The [`parse_macro_input!`] macro provides a convenient way to invoke
+    /// this method correctly in a procedural macro.
+    ///
+    /// [`compile_error!`]: std::compile_error!
+    /// [`parse_macro_input!`]: crate::parse_macro_input!
+    pub fn to_compile_error(&self) -> TokenStream {
+        self.messages
+            .iter()
+            .map(ErrorMessage::to_compile_error)
+            .collect()
+    }
+
+    /// Render the error as an invocation of [`compile_error!`].
+    ///
+    /// [`compile_error!`]: std::compile_error!
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// # extern crate proc_macro;
+    /// #
+    /// use proc_macro::TokenStream;
+    /// use syn::{parse_macro_input, DeriveInput, Error};
+    ///
+    /// # const _: &str = stringify! {
+    /// #[proc_macro_derive(MyTrait)]
+    /// # };
+    /// pub fn derive_my_trait(input: TokenStream) -> TokenStream {
+    ///     let input = parse_macro_input!(input as DeriveInput);
+    ///     my_trait::expand(input)
+    ///         .unwrap_or_else(Error::into_compile_error)
+    ///         .into()
+    /// }
+    ///
+    /// mod my_trait {
+    ///     use proc_macro2::TokenStream;
+    ///     use syn::{DeriveInput, Result};
+    ///
+    ///     pub(crate) fn expand(input: DeriveInput) -> Result<TokenStream> {
+    ///         /* ... */
+    ///         # unimplemented!()
+    ///     }
+    /// }
+    /// ```
+    pub fn into_compile_error(self) -> TokenStream {
+        self.to_compile_error()
+    }
+
+    /// Add another error message to self such that when `to_compile_error()` is
+    /// called, both errors will be emitted together.
+    pub fn combine(&mut self, another: Error) {
+        self.messages.extend(another.messages);
+    }
+}
+
+impl ErrorMessage {
+    fn to_compile_error(&self) -> TokenStream {
+        let (start, end) = match self.span.get() {
+            Some(range) => (range.start, range.end),
+            None => (Span::call_site(), Span::call_site()),
+        };
+
+        // ::core::compile_error!($message)
+        TokenStream::from_iter(vec![
+            TokenTree::Punct({
+                let mut punct = Punct::new(':', Spacing::Joint);
+                punct.set_span(start);
+                punct
+            }),
+            TokenTree::Punct({
+                let mut punct = Punct::new(':', Spacing::Alone);
+                punct.set_span(start);
+                punct
+            }),
+            TokenTree::Ident(Ident::new("core", start)),
+            TokenTree::Punct({
+                let mut punct = Punct::new(':', Spacing::Joint);
+                punct.set_span(start);
+                punct
+            }),
+            TokenTree::Punct({
+                let mut punct = Punct::new(':', Spacing::Alone);
+                punct.set_span(start);
+                punct
+            }),
+            TokenTree::Ident(Ident::new("compile_error", start)),
+            TokenTree::Punct({
+                let mut punct = Punct::new('!', Spacing::Alone);
+                punct.set_span(start);
+                punct
+            }),
+            TokenTree::Group({
+                let mut group = Group::new(Delimiter::Brace, {
+                    TokenStream::from_iter(vec![TokenTree::Literal({
+                        let mut string = Literal::string(&self.message);
+                        string.set_span(end);
+                        string
+                    })])
+                });
+                group.set_span(end);
+                group
+            }),
+        ])
+    }
+}
+
+#[cfg(feature = "parsing")]
+pub(crate) fn new_at<T: Display>(scope: Span, cursor: Cursor, message: T) -> Error {
+    if cursor.eof() {
+        Error::new(scope, format!("unexpected end of input, {}", message))
+    } else {
+        let span = crate::buffer::open_span_of_group(cursor);
+        Error::new(span, message)
+    }
+}
+
+#[cfg(all(feature = "parsing", any(feature = "full", feature = "derive")))]
+pub(crate) fn new2<T: Display>(start: Span, end: Span, message: T) -> Error {
+    return new2(start, end, message.to_string());
+
+    fn new2(start: Span, end: Span, message: String) -> Error {
+        Error {
+            messages: vec![ErrorMessage {
+                span: ThreadBound::new(SpanRange { start, end }),
+                message,
+            }],
+        }
+    }
+}
+
+impl Debug for Error {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        if self.messages.len() == 1 {
+            formatter
+                .debug_tuple("Error")
+                .field(&self.messages[0])
+                .finish()
+        } else {
+            formatter
+                .debug_tuple("Error")
+                .field(&self.messages)
+                .finish()
+        }
+    }
+}
+
+impl Debug for ErrorMessage {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        Debug::fmt(&self.message, formatter)
+    }
+}
+
+impl Display for Error {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str(&self.messages[0].message)
+    }
+}
+
+impl Clone for Error {
+    fn clone(&self) -> Self {
+        Error {
+            messages: self.messages.clone(),
+        }
+    }
+}
+
+impl Clone for ErrorMessage {
+    fn clone(&self) -> Self {
+        ErrorMessage {
+            span: self.span,
+            message: self.message.clone(),
+        }
+    }
+}
+
+impl Clone for SpanRange {
+    fn clone(&self) -> Self {
+        *self
+    }
+}
+
+impl Copy for SpanRange {}
+
+impl std::error::Error for Error {}
+
+impl From<LexError> for Error {
+    fn from(err: LexError) -> Self {
+        Error::new(err.span(), err)
+    }
+}
+
+impl IntoIterator for Error {
+    type Item = Error;
+    type IntoIter = IntoIter;
+
+    fn into_iter(self) -> Self::IntoIter {
+        IntoIter {
+            messages: self.messages.into_iter(),
+        }
+    }
+}
+
+pub struct IntoIter {
+    messages: vec::IntoIter<ErrorMessage>,
+}
+
+impl Iterator for IntoIter {
+    type Item = Error;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        Some(Error {
+            messages: vec![self.messages.next()?],
+        })
+    }
+}
+
+impl<'a> IntoIterator for &'a Error {
+    type Item = Error;
+    type IntoIter = Iter<'a>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        Iter {
+            messages: self.messages.iter(),
+        }
+    }
+}
+
+pub struct Iter<'a> {
+    messages: slice::Iter<'a, ErrorMessage>,
+}
+
+impl<'a> Iterator for Iter<'a> {
+    type Item = Error;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        Some(Error {
+            messages: vec![self.messages.next()?.clone()],
+        })
+    }
+}
+
+impl Extend<Error> for Error {
+    fn extend<T: IntoIterator<Item = Error>>(&mut self, iter: T) {
+        for err in iter {
+            self.combine(err);
+        }
+    }
+}