Fix handling of Self keyword in type definition

serde_derive/Cargo.toml

@@ -22,7 +22,7 @@ proc-macro = true
 [dependencies]
 proc-macro2 = "1.0"
 quote = "1.0"
-syn = { version = "1.0.58", features = ["visit"] }
+syn = { version = "1.0.58", features = ["visit", "visit-mut"] }
 
 [dev-dependencies]
 serde = { version = "1.0", path = "../serde" }

serde_derive/src/de.rs

@@ -8,13 +8,17 @@ use bound;
 use dummy;
 use fragment::{Expr, Fragment, Match, Stmts};
 use internals::ast::{Container, Data, Field, Style, Variant};
-use internals::{attr, ungroup, Ctxt, Derive};
+use internals::{attr, replace_receiver, ungroup, Ctxt, Derive};
 use pretend;
 
 use std::collections::BTreeSet;
 use std::ptr;
 
-pub fn expand_derive_deserialize(input: &syn::DeriveInput) -> Result<TokenStream, Vec<syn::Error>> {
+pub fn expand_derive_deserialize(
+    input: &mut syn::DeriveInput,
+) -> Result<TokenStream, Vec<syn::Error>> {
+    replace_receiver(input);
+
     let ctxt = Ctxt::new();
     let cont = match Container::from_ast(&ctxt, input, Derive::Deserialize) {
         Some(cont) => cont,

serde_derive/src/internals/mod.rs

@@ -4,8 +4,12 @@ pub mod attr;
 mod ctxt;
 pub use self::ctxt::Ctxt;
 
+mod receiver;
+pub use self::receiver::replace_receiver;
+
 mod case;
 mod check;
+mod respan;
 mod symbol;
 
 use syn::Type;

serde_derive/src/internals/receiver.rs

@@ -0,0 +1,178 @@
+use super::respan::respan;
+use proc_macro2::{Group, Spacing, Span, TokenStream, TokenTree};
+use quote::{quote, quote_spanned};
+use std::{iter::FromIterator, mem};
+use syn::{
+    parse_quote,
+    punctuated::Punctuated,
+    visit_mut::{self, VisitMut},
+    DeriveInput, ExprPath, Macro, Path, PathArguments, QSelf, Type, TypePath,
+};
+
+pub fn replace_receiver(input: &mut DeriveInput) {
+    let ident = &input.ident;
+    let ty_generics = input.generics.split_for_impl().1;
+    let self_ty = parse_quote!(#ident #ty_generics);
+    let mut visitor = ReplaceReceiver(&self_ty);
+    visitor.visit_generics_mut(&mut input.generics);
+    visitor.visit_data_mut(&mut input.data);
+}
+
+struct ReplaceReceiver<'a>(&'a TypePath);
+
+impl ReplaceReceiver<'_> {
+    fn self_ty(&self, span: Span) -> TypePath {
+        respan(self.0, span)
+    }
+
+    fn self_to_qself(&self, qself: &mut Option<QSelf>, path: &mut Path) {
+        if path.leading_colon.is_some() {
+            return;
+        }
+
+        let first = &path.segments[0];
+        if first.ident != "Self" || !first.arguments.is_empty() {
+            return;
+        }
+
+        if path.segments.len() == 1 {
+            self.self_to_expr_path(path);
+            return;
+        }
+
+        let span = first.ident.span();
+        *qself = Some(QSelf {
+            lt_token: Token![<](span),
+            ty: Box::new(self.self_ty(span).into()),
+            position: 0,
+            as_token: None,
+            gt_token: Token![>](span),
+        });
+
+        path.leading_colon = Some(**path.segments.pairs().next().unwrap().punct().unwrap());
+
+        let segments = mem::replace(&mut path.segments, Punctuated::new());
+        path.segments = segments.into_pairs().skip(1).collect();
+    }
+
+    fn self_to_expr_path(&self, path: &mut Path) {
+        if path.leading_colon.is_some() {
+            return;
+        }
+
+        let first = &path.segments[0];
+        if first.ident != "Self" || !first.arguments.is_empty() {
+            return;
+        }
+
+        let self_ty = self.self_ty(first.ident.span());
+        let variant = mem::replace(path, self_ty.path);
+        for segment in &mut path.segments {
+            if let PathArguments::AngleBracketed(bracketed) = &mut segment.arguments {
+                if bracketed.colon2_token.is_none() && !bracketed.args.is_empty() {
+                    bracketed.colon2_token = Some(<Token![::]>::default());
+                }
+            }
+        }
+        if variant.segments.len() > 1 {
+            path.segments.push_punct(<Token![::]>::default());
+            path.segments.extend(variant.segments.into_pairs().skip(1));
+        }
+    }
+
+    fn visit_token_stream(&self, tokens: &mut TokenStream) -> bool {
+        let mut out = Vec::new();
+        let mut modified = false;
+        let mut iter = tokens.clone().into_iter().peekable();
+        while let Some(tt) = iter.next() {
+            match tt {
+                TokenTree::Ident(ident) => {
+                    if ident == "Self" {
+                        modified = true;
+                        let self_ty = self.self_ty(ident.span());
+                        match iter.peek() {
+                            Some(TokenTree::Punct(p))
+                                if p.as_char() == ':' && p.spacing() == Spacing::Joint =>
+                            {
+                                let next = iter.next().unwrap();
+                                match iter.peek() {
+                                    Some(TokenTree::Punct(p)) if p.as_char() == ':' => {
+                                        let span = ident.span();
+                                        out.extend(quote_spanned!(span=> <#self_ty>));
+                                    }
+                                    _ => out.extend(quote!(#self_ty)),
+                                }
+                                out.push(next);
+                            }
+                            _ => out.extend(quote!(#self_ty)),
+                        }
+                    } else {
+                        out.push(TokenTree::Ident(ident));
+                    }
+                }
+                TokenTree::Group(group) => {
+                    let mut content = group.stream();
+                    modified |= self.visit_token_stream(&mut content);
+                    let mut new = Group::new(group.delimiter(), content);
+                    new.set_span(group.span());
+                    out.push(TokenTree::Group(new));
+                }
+                other => out.push(other),
+            }
+        }
+        if modified {
+            *tokens = TokenStream::from_iter(out);
+        }
+        modified
+    }
+}
+
+impl VisitMut for ReplaceReceiver<'_> {
+    // `Self` -> `Receiver`
+    fn visit_type_mut(&mut self, ty: &mut Type) {
+        if let Type::Path(node) = ty {
+            if node.qself.is_none() && node.path.is_ident("Self") {
+                *ty = self.self_ty(node.path.segments[0].ident.span()).into();
+            } else {
+                self.visit_type_path_mut(node);
+            }
+        } else {
+            visit_mut::visit_type_mut(self, ty);
+        }
+    }
+
+    // `Self::Assoc` -> `<Receiver>::Assoc`
+    fn visit_type_path_mut(&mut self, ty: &mut TypePath) {
+        if ty.qself.is_none() {
+            self.self_to_qself(&mut ty.qself, &mut ty.path);
+        }
+        visit_mut::visit_type_path_mut(self, ty);
+    }
+
+    // `Self::method` -> `<Receiver>::method`
+    fn visit_expr_path_mut(&mut self, expr: &mut ExprPath) {
+        if expr.qself.is_none() {
+            self.self_to_qself(&mut expr.qself, &mut expr.path);
+        }
+        visit_mut::visit_expr_path_mut(self, expr);
+    }
+
+    fn visit_macro_mut(&mut self, mac: &mut Macro) {
+        // We can't tell in general whether `self` inside a macro invocation
+        // refers to the self in the argument list or a different self
+        // introduced within the macro. Heuristic: if the macro input contains
+        // `fn`, then `self` is more likely to refer to something other than the
+        // outer function's self argument.
+        if !contains_fn(mac.tokens.clone()) {
+            self.visit_token_stream(&mut mac.tokens);
+        }
+    }
+}
+
+fn contains_fn(tokens: TokenStream) -> bool {
+    tokens.into_iter().any(|tt| match tt {
+        TokenTree::Ident(ident) => ident == "fn",
+        TokenTree::Group(group) => contains_fn(group.stream()),
+        _ => false,
+    })
+}

serde_derive/src/internals/respan.rs

@@ -0,0 +1,22 @@
+use proc_macro2::{Span, TokenStream};
+use quote::ToTokens;
+use syn::parse::Parse;
+
+pub(crate) fn respan<T>(node: &T, span: Span) -> T
+where
+    T: ToTokens + Parse,
+{
+    let tokens = node.to_token_stream();
+    let respanned = respan_tokens(tokens, span);
+    syn::parse2(respanned).unwrap()
+}
+
+fn respan_tokens(tokens: TokenStream, span: Span) -> TokenStream {
+    tokens
+        .into_iter()
+        .map(|mut token| {
+            token.set_span(span);
+            token
+        })
+        .collect()
+}

serde_derive/src/lib.rs

@@ -86,8 +86,8 @@ pub fn derive_serialize(input: TokenStream) -> TokenStream {
 
 #[proc_macro_derive(Deserialize, attributes(serde))]
 pub fn derive_deserialize(input: TokenStream) -> TokenStream {
-    let input = parse_macro_input!(input as DeriveInput);
-    de::expand_derive_deserialize(&input)
+    let mut input = parse_macro_input!(input as DeriveInput);
+    de::expand_derive_deserialize(&mut input)
         .unwrap_or_else(to_compile_errors)
         .into()
 }

serde_derive_internals/Cargo.toml

@@ -16,7 +16,7 @@ path = "lib.rs"
 [dependencies]
 proc-macro2 = "1.0"
 quote = "1.0"
-syn = { version = "1.0.33", default-features = false, features = ["derive", "parsing", "printing", "clone-impls"] }
+syn = { version = "1.0.33", default-features = false, features = ["derive", "parsing", "printing", "clone-impls", "visit-mut"] }
 
 [package.metadata.docs.rs]
 targets = ["x86_64-unknown-linux-gnu"]

test_suite/tests/test_self.rs

@@ -0,0 +1,101 @@
+use serde::{Deserialize, Serialize};
+
+#[test]
+fn test_self() {
+    macro_rules! mac {
+        ($($tt:tt)*) => {
+            $($tt)*
+        };
+    }
+
+    pub trait Trait {
+        type Assoc;
+    }
+
+    #[derive(Deserialize, Serialize)]
+    pub struct Generics<T: Trait<Assoc = Self>>
+    where
+        Self: Trait<Assoc = Self>,
+        <Self as Trait>::Assoc: Sized,
+        mac!(Self): Trait<Assoc = mac!(Self)>,
+    {
+        _f: T,
+    }
+
+    impl<T: Trait<Assoc = Self>> Trait for Generics<T> {
+        type Assoc = Self;
+    }
+
+    #[derive(Deserialize, Serialize)]
+    pub struct Struct {
+        _f1: Box<Self>,
+        _f2: Box<<Self as Trait>::Assoc>,
+        _f3: Box<mac!(Self)>,
+        _f4: [(); Self::ASSOC],
+        _f5: [(); Self::assoc()],
+        _f6: [(); mac!(Self::assoc())],
+    }
+
+    impl Struct {
+        const ASSOC: usize = 1;
+        const fn assoc() -> usize {
+            0
+        }
+    }
+
+    impl Trait for Struct {
+        type Assoc = Self;
+    }
+
+    #[derive(Deserialize, Serialize)]
+    struct Tuple(
+        Box<Self>,
+        Box<<Self as Trait>::Assoc>,
+        Box<mac!(Self)>,
+        [(); Self::ASSOC],
+        [(); Self::assoc()],
+        [(); mac!(Self::assoc())],
+    );
+
+    impl Tuple {
+        const ASSOC: usize = 1;
+        const fn assoc() -> usize {
+            0
+        }
+    }
+
+    impl Trait for Tuple {
+        type Assoc = Self;
+    }
+
+    #[derive(Deserialize, Serialize)]
+    enum Enum {
+        Struct {
+            _f1: Box<Self>,
+            _f2: Box<<Self as Trait>::Assoc>,
+            _f3: Box<mac!(Self)>,
+            _f4: [(); Self::ASSOC],
+            _f5: [(); Self::assoc()],
+            _f6: [(); mac!(Self::assoc())],
+        },
+        Tuple(
+            Box<Self>,
+            Box<<Self as Trait>::Assoc>,
+            Box<mac!(Self)>,
+            [(); Self::ASSOC],
+            [(); Self::assoc()],
+            [(); mac!(Self::assoc())],
+        ),
+    }
+
+    impl Enum {
+        const ASSOC: usize = 1;
+        const fn assoc() -> usize {
+            0
+        }
+    }
+
+    impl Trait for Enum {
+        type Assoc = Self;
+    }
+}