mod.rs.html -- source
Description: Source to the Rust file `library/proc_macro/src/bridge/mod.rs`.
Keywords: rust, rustlang, rust-lang

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    //! Internal interface for communicating between a `proc_macro` client
    //! (a proc macro crate) and a `proc_macro` server (a compiler front-end).
    //!
    //! Serialization (with C ABI buffers) and unique integer handles are employed
    //! to allow safely interfacing between two copies of `proc_macro` built
    //! (from the same source) by different compilers with potentially mismatching
    //! Rust ABIs (e.g., stage0/bin/rustc vs stage1/bin/rustc during bootstrap).

    #![deny(unsafe_code)]

    use crate::{Delimiter, Level, LineColumn, Spacing};
    use std::fmt;
    use std::hash::Hash;
    use std::marker;
    use std::mem;
    use std::ops::Bound;
    use std::panic;
    use std::sync::atomic::AtomicUsize;
    use std::sync::Once;
    use std::thread;

    /// Higher-order macro describing the server RPC API, allowing automatic
    /// generation of type-safe Rust APIs, both client-side and server-side.
    ///
    /// `with_api!(MySelf, my_self, my_macro)` expands to:
    /// ```rust,ignore (pseudo-code)
    /// my_macro! {
    ///     // ...
    ///     Literal {
    ///         // ...
    ///         fn character(ch: char) -> MySelf::Literal;
    ///         // ...
    ///         fn span(my_self: &MySelf::Literal) -> MySelf::Span;
    ///         fn set_span(my_self: &mut MySelf::Literal, span: MySelf::Span);
    ///     },
    ///     // ...
    /// }
    /// ```
    ///
    /// The first two arguments serve to customize the arguments names
    /// and argument/return types, to enable several different usecases:
    ///
    /// If `my_self` is just `self`, then each `fn` signature can be used
    /// as-is for a method. If it's anything else (`self_` in practice),
    /// then the signatures don't have a special `self` argument, and
    /// can, therefore, have a different one introduced.
    ///
    /// If `MySelf` is just `Self`, then the types are only valid inside
    /// a trait or a trait impl, where the trait has associated types
    /// for each of the API types. If non-associated types are desired,
    /// a module name (`self` in practice) can be used instead of `Self`.
    macro_rules! with_api {
        ($S:ident, $self:ident, $m:ident) => {
            $m! {
                FreeFunctions {
                    fn drop($self: $S::FreeFunctions);
                    fn track_env_var(var: &str, value: Option<&str>);
                },
                TokenStream {
                    fn drop($self: $S::TokenStream);
                    fn clone($self: &$S::TokenStream) -> $S::TokenStream;
                    fn new() -> $S::TokenStream;
                    fn is_empty($self: &$S::TokenStream) -> bool;
                    fn from_str(src: &str) -> $S::TokenStream;
                    fn to_string($self: &$S::TokenStream) -> String;
                    fn from_token_tree(
                        tree: TokenTree<$S::Group, $S::Punct, $S::Ident, $S::Literal>,
                    ) -> $S::TokenStream;
                    fn into_iter($self: $S::TokenStream) -> $S::TokenStreamIter;
                },
                TokenStreamBuilder {
                    fn drop($self: $S::TokenStreamBuilder);
                    fn new() -> $S::TokenStreamBuilder;
                    fn push($self: &mut $S::TokenStreamBuilder, stream: $S::TokenStream);
                    fn build($self: $S::TokenStreamBuilder) -> $S::TokenStream;
                },
                TokenStreamIter {
                    fn drop($self: $S::TokenStreamIter);
                    fn clone($self: &$S::TokenStreamIter) -> $S::TokenStreamIter;
                    fn next(
                        $self: &mut $S::TokenStreamIter,
                    ) -> Option<TokenTree<$S::Group, $S::Punct, $S::Ident, $S::Literal>>;
                },
                Group {
                    fn drop($self: $S::Group);
                    fn clone($self: &$S::Group) -> $S::Group;
                    fn new(delimiter: Delimiter, stream: $S::TokenStream) -> $S::Group;
                    fn delimiter($self: &$S::Group) -> Delimiter;
                    fn stream($self: &$S::Group) -> $S::TokenStream;
                    fn span($self: &$S::Group) -> $S::Span;
                    fn span_open($self: &$S::Group) -> $S::Span;
                    fn span_close($self: &$S::Group) -> $S::Span;
                    fn set_span($self: &mut $S::Group, span: $S::Span);
                },
                Punct {
                    fn new(ch: char, spacing: Spacing) -> $S::Punct;
                    fn as_char($self: $S::Punct) -> char;
                    fn spacing($self: $S::Punct) -> Spacing;
                    fn span($self: $S::Punct) -> $S::Span;
                    fn with_span($self: $S::Punct, span: $S::Span) -> $S::Punct;
                },
                Ident {
                    fn new(string: &str, span: $S::Span, is_raw: bool) -> $S::Ident;
                    fn span($self: $S::Ident) -> $S::Span;
                    fn with_span($self: $S::Ident, span: $S::Span) -> $S::Ident;
                },
                Literal {
                    fn drop($self: $S::Literal);
                    fn clone($self: &$S::Literal) -> $S::Literal;
                    fn debug_kind($self: &$S::Literal) -> String;
                    fn symbol($self: &$S::Literal) -> String;
                    fn suffix($self: &$S::Literal) -> Option<String>;
                    fn integer(n: &str) -> $S::Literal;
                    fn typed_integer(n: &str, kind: &str) -> $S::Literal;
                    fn float(n: &str) -> $S::Literal;
                    fn f32(n: &str) -> $S::Literal;
                    fn f64(n: &str) -> $S::Literal;
                    fn string(string: &str) -> $S::Literal;
                    fn character(ch: char) -> $S::Literal;
                    fn byte_string(bytes: &[u8]) -> $S::Literal;
                    fn span($self: &$S::Literal) -> $S::Span;
                    fn set_span($self: &mut $S::Literal, span: $S::Span);
                    fn subspan(
                        $self: &$S::Literal,
                        start: Bound<usize>,
                        end: Bound<usize>,
                    ) -> Option<$S::Span>;
                },
                SourceFile {
                    fn drop($self: $S::SourceFile);
                    fn clone($self: &$S::SourceFile) -> $S::SourceFile;
                    fn eq($self: &$S::SourceFile, other: &$S::SourceFile) -> bool;
                    fn path($self: &$S::SourceFile) -> String;
                    fn is_real($self: &$S::SourceFile) -> bool;
                },
                MultiSpan {
                    fn drop($self: $S::MultiSpan);
                    fn new() -> $S::MultiSpan;
                    fn push($self: &mut $S::MultiSpan, span: $S::Span);
                },
                Diagnostic {
                    fn drop($self: $S::Diagnostic);
                    fn new(level: Level, msg: &str, span: $S::MultiSpan) -> $S::Diagnostic;
                    fn sub(
                        $self: &mut $S::Diagnostic,
                        level: Level,
                        msg: &str,
                        span: $S::MultiSpan,
                    );
                    fn emit($self: $S::Diagnostic);
                },
                Span {
                    fn debug($self: $S::Span) -> String;
                    fn def_site() -> $S::Span;
                    fn call_site() -> $S::Span;
                    fn mixed_site() -> $S::Span;
                    fn source_file($self: $S::Span) -> $S::SourceFile;
                    fn parent($self: $S::Span) -> Option<$S::Span>;
                    fn source($self: $S::Span) -> $S::Span;
                    fn start($self: $S::Span) -> LineColumn;
                    fn end($self: $S::Span) -> LineColumn;
                    fn join($self: $S::Span, other: $S::Span) -> Option<$S::Span>;
                    fn resolved_at($self: $S::Span, at: $S::Span) -> $S::Span;
                    fn source_text($self: $S::Span) -> Option<String>;
                },
            }
        };
    }

    // FIXME(eddyb) this calls `encode` for each argument, but in reverse,
    // to avoid borrow conflicts from borrows started by `&mut` arguments.
    macro_rules! reverse_encode {
        ($writer:ident;) => {};
        ($writer:ident; $first:ident $(, $rest:ident)*) => {
            reverse_encode!($writer; $($rest),*);
            $first.encode(&mut $writer, &mut ());
        }
    }

    // FIXME(eddyb) this calls `decode` for each argument, but in reverse,
    // to avoid borrow conflicts from borrows started by `&mut` arguments.
    macro_rules! reverse_decode {
        ($reader:ident, $s:ident;) => {};
        ($reader:ident, $s:ident; $first:ident: $first_ty:ty $(, $rest:ident: $rest_ty:ty)*) => {
            reverse_decode!($reader, $s; $($rest: $rest_ty),*);
            let $first = <$first_ty>::decode(&mut $reader, $s);
        }
    }

    #[allow(unsafe_code)]
    mod buffer;
    #[forbid(unsafe_code)]
    pub mod client;
    #[allow(unsafe_code)]
    mod closure;
    #[forbid(unsafe_code)]
    mod handle;
    #[macro_use]
    #[forbid(unsafe_code)]
    mod rpc;
    #[allow(unsafe_code)]
    mod scoped_cell;
    #[forbid(unsafe_code)]
    pub mod server;

    use buffer::Buffer;
    pub use rpc::PanicMessage;
    use rpc::{Decode, DecodeMut, Encode, Reader, Writer};

    /// An active connection between a server and a client.
    /// The server creates the bridge (`Bridge::run_server` in `server.rs`),
    /// then passes it to the client through the function pointer in the `run`
    /// field of `client::Client`. The client holds its copy of the `Bridge`
    /// in TLS during its execution (`Bridge::{enter, with}` in `client.rs`).
    #[repr(C)]
    pub struct Bridge<'a> {
        /// Reusable buffer (only `clear`-ed, never shrunk), primarily
        /// used for making requests, but also for passing input to client.
        cached_buffer: Buffer<u8>,

        /// Server-side function that the client uses to make requests.
        dispatch: closure::Closure<'a, Buffer<u8>, Buffer<u8>>,

        /// If 'true', always invoke the default panic hook
        force_show_panics: bool,
    }

    impl<'a> !Sync for Bridge<'a> {}
    impl<'a> !Send for Bridge<'a> {}

    #[forbid(unsafe_code)]
    #[allow(non_camel_case_types)]
    mod api_tags {
        use super::rpc::{DecodeMut, Encode, Reader, Writer};

        macro_rules! declare_tags {
            ($($name:ident {
                $(fn $method:ident($($arg:ident: $arg_ty:ty),* $(,)?) $(-> $ret_ty:ty)*;)*
            }),* $(,)?) => {
                $(
                    pub(super) enum $name {
                        $($method),*
                    }
                    rpc_encode_decode!(enum $name { $($method),* });
                )*

                pub(super) enum Method {
                    $($name($name)),*
                }
                rpc_encode_decode!(enum Method { $($name(m)),* });
            }
        }
        with_api!(self, self, declare_tags);
    }

    /// Helper to wrap associated types to allow trait impl dispatch.
    /// That is, normally a pair of impls for `T::Foo` and `T::Bar`
    /// can overlap, but if the impls are, instead, on types like
    /// `Marked<T::Foo, Foo>` and `Marked<T::Bar, Bar>`, they can't.
    trait Mark {
        type Unmarked;
        fn mark(unmarked: Self::Unmarked) -> Self;
    }

    /// Unwrap types wrapped by `Mark::mark` (see `Mark` for details).
    trait Unmark {
        type Unmarked;
        fn unmark(self) -> Self::Unmarked;
    }

    #[derive(Copy, Clone, PartialEq, Eq, Hash)]
    struct Marked<T, M> {
        value: T,
        _marker: marker::PhantomData<M>,
    }

    impl<T, M> Mark for Marked<T, M> {
        type Unmarked = T;
        fn mark(unmarked: Self::Unmarked) -> Self {
            Marked { value: unmarked, _marker: marker::PhantomData }
        }
    }
    impl<T, M> Unmark for Marked<T, M> {
        type Unmarked = T;
        fn unmark(self) -> Self::Unmarked {
            self.value
        }
    }
    impl<T, M> Unmark for &'a Marked<T, M> {
        type Unmarked = &'a T;
        fn unmark(self) -> Self::Unmarked {
            &self.value
        }
    }
    impl<T, M> Unmark for &'a mut Marked<T, M> {
        type Unmarked = &'a mut T;
        fn unmark(self) -> Self::Unmarked {
            &mut self.value
        }
    }

    impl<T: Mark> Mark for Option<T> {
        type Unmarked = Option<T::Unmarked>;
        fn mark(unmarked: Self::Unmarked) -> Self {
            unmarked.map(T::mark)
        }
    }
    impl<T: Unmark> Unmark for Option<T> {
        type Unmarked = Option<T::Unmarked>;
        fn unmark(self) -> Self::Unmarked {
            self.map(T::unmark)
        }
    }

    macro_rules! mark_noop {
        ($($ty:ty),* $(,)?) => {
            $(
                impl Mark for $ty {
                    type Unmarked = Self;
                    fn mark(unmarked: Self::Unmarked) -> Self {
                        unmarked
                    }
                }
                impl Unmark for $ty {
                    type Unmarked = Self;
                    fn unmark(self) -> Self::Unmarked {
                        self
                    }
                }
            )*
        }
    }
    mark_noop! {
        (),
        bool,
        char,
        &'a [u8],
        &'a str,
        String,
        Delimiter,
        Level,
        LineColumn,
        Spacing,
        Bound<usize>,
    }

    rpc_encode_decode!(
        enum Delimiter {
            Parenthesis,
            Brace,
            Bracket,
            None,
        }
    );
    rpc_encode_decode!(
        enum Level {
            Error,
            Warning,
            Note,
            Help,
        }
    );
    rpc_encode_decode!(struct LineColumn { line, column });
    rpc_encode_decode!(
        enum Spacing {
            Alone,
            Joint,
        }
    );

    #[derive(Clone)]
    pub enum TokenTree<G, P, I, L> {
        Group(G),
        Punct(P),
        Ident(I),
        Literal(L),
    }

    impl<G: Mark, P: Mark, I: Mark, L: Mark> Mark for TokenTree<G, P, I, L> {
        type Unmarked = TokenTree<G::Unmarked, P::Unmarked, I::Unmarked, L::Unmarked>;
        fn mark(unmarked: Self::Unmarked) -> Self {
            match unmarked {
                TokenTree::Group(tt) => TokenTree::Group(G::mark(tt)),
                TokenTree::Punct(tt) => TokenTree::Punct(P::mark(tt)),
                TokenTree::Ident(tt) => TokenTree::Ident(I::mark(tt)),
                TokenTree::Literal(tt) => TokenTree::Literal(L::mark(tt)),
            }
        }
    }
    impl<G: Unmark, P: Unmark, I: Unmark, L: Unmark> Unmark for TokenTree<G, P, I, L> {
        type Unmarked = TokenTree<G::Unmarked, P::Unmarked, I::Unmarked, L::Unmarked>;
        fn unmark(self) -> Self::Unmarked {
            match self {
                TokenTree::Group(tt) => TokenTree::Group(tt.unmark()),
                TokenTree::Punct(tt) => TokenTree::Punct(tt.unmark()),
                TokenTree::Ident(tt) => TokenTree::Ident(tt.unmark()),
                TokenTree::Literal(tt) => TokenTree::Literal(tt.unmark()),
            }
        }
    }

    rpc_encode_decode!(
        enum TokenTree<G, P, I, L> {
            Group(tt),
            Punct(tt),
            Ident(tt),
            Literal(tt),
        }
    );