1 files changed, 179 insertions, 0 deletions
diff --git a/third_party/rust/async-trait/src/receiver.rs b/third_party/rust/async-trait/src/receiver.rs
new file mode 100644
index 0000000000..2230db6ea2
--- /dev/null
+++ b/third_party/rust/async-trait/src/receiver.rs
@@ -0,0 +1,179 @@
+use proc_macro2::{Group, Span, TokenStream, TokenTree};
+use std::iter::FromIterator;
+use syn::visit_mut::{self, VisitMut};
+use syn::{
+    Block, ExprPath, Ident, Item, Macro, Pat, PatIdent, PatPath, Path, Receiver, Signature, Token,
+    TypePath,
+};
+
+pub fn has_self_in_sig(sig: &mut Signature) -> bool {
+    let mut visitor = HasSelf(false);
+    visitor.visit_signature_mut(sig);
+    visitor.0
+}
+
+pub fn has_self_in_block(block: &mut Block) -> bool {
+    let mut visitor = HasSelf(false);
+    visitor.visit_block_mut(block);
+    visitor.0
+}
+
+fn has_self_in_token_stream(tokens: TokenStream) -> bool {
+    tokens.into_iter().any(|tt| match tt {
+        TokenTree::Ident(ident) => ident == "Self",
+        TokenTree::Group(group) => has_self_in_token_stream(group.stream()),
+        _ => false,
+    })
+}
+
+pub fn mut_pat(pat: &mut Pat) -> Option<Token![mut]> {
+    let mut visitor = HasMutPat(None);
+    visitor.visit_pat_mut(pat);
+    visitor.0
+}
+
+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,
+    })
+}
+
+struct HasMutPat(Option<Token![mut]>);
+
+impl VisitMut for HasMutPat {
+    fn visit_pat_ident_mut(&mut self, i: &mut PatIdent) {
+        if let Some(m) = i.mutability {
+            self.0 = Some(m);
+        } else {
+            visit_mut::visit_pat_ident_mut(self, i);
+        }
+    }
+}
+
+struct HasSelf(bool);
+
+impl VisitMut for HasSelf {
+    fn visit_expr_path_mut(&mut self, expr: &mut ExprPath) {
+        self.0 |= expr.path.segments[0].ident == "Self";
+        visit_mut::visit_expr_path_mut(self, expr);
+    }
+
+    fn visit_pat_path_mut(&mut self, pat: &mut PatPath) {
+        self.0 |= pat.path.segments[0].ident == "Self";
+        visit_mut::visit_pat_path_mut(self, pat);
+    }
+
+    fn visit_type_path_mut(&mut self, ty: &mut TypePath) {
+        self.0 |= ty.path.segments[0].ident == "Self";
+        visit_mut::visit_type_path_mut(self, ty);
+    }
+
+    fn visit_receiver_mut(&mut self, _arg: &mut Receiver) {
+        self.0 = true;
+    }
+
+    fn visit_item_mut(&mut self, _: &mut Item) {
+        // Do not recurse into nested items.
+    }
+
+    fn visit_macro_mut(&mut self, mac: &mut Macro) {
+        if !contains_fn(mac.tokens.clone()) {
+            self.0 |= has_self_in_token_stream(mac.tokens.clone());
+        }
+    }
+}
+
+pub struct ReplaceSelf(pub Span);
+
+impl ReplaceSelf {
+    #[cfg_attr(not(self_span_hack), allow(clippy::unused_self))]
+    fn prepend_underscore_to_self(&self, ident: &mut Ident) -> bool {
+        let modified = ident == "self";
+        if modified {
+            *ident = Ident::new("__self", ident.span());
+            #[cfg(self_span_hack)]
+            ident.set_span(self.0);
+        }
+        modified
+    }
+
+    fn visit_token_stream(&mut self, tokens: &mut TokenStream) -> bool {
+        let mut out = Vec::new();
+        let mut modified = false;
+        visit_token_stream_impl(self, tokens.clone(), &mut modified, &mut out);
+        if modified {
+            *tokens = TokenStream::from_iter(out);
+        }
+        return modified;
+
+        fn visit_token_stream_impl(
+            visitor: &mut ReplaceSelf,
+            tokens: TokenStream,
+            modified: &mut bool,
+            out: &mut Vec<TokenTree>,
+        ) {
+            for tt in tokens {
+                match tt {
+                    TokenTree::Ident(mut ident) => {
+                        *modified |= visitor.prepend_underscore_to_self(&mut ident);
+                        out.push(TokenTree::Ident(ident));
+                    }
+                    TokenTree::Group(group) => {
+                        let mut content = group.stream();
+                        *modified |= visitor.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),
+                }
+            }
+        }
+    }
+}
+
+impl VisitMut for ReplaceSelf {
+    fn visit_ident_mut(&mut self, i: &mut Ident) {
+        self.prepend_underscore_to_self(i);
+    }
+
+    fn visit_path_mut(&mut self, p: &mut Path) {
+        if p.segments.len() == 1 {
+            // Replace `self`, but not `self::function`.
+            self.visit_ident_mut(&mut p.segments[0].ident);
+        }
+        for segment in &mut p.segments {
+            self.visit_path_arguments_mut(&mut segment.arguments);
+        }
+    }
+
+    fn visit_item_mut(&mut self, i: &mut Item) {
+        // Visit `macro_rules!` because locally defined macros can refer to
+        // `self`.
+        //
+        // Visit `futures::select` and similar select macros, which commonly
+        // appear syntactically like an item despite expanding to an expression.
+        //
+        // Otherwise, do not recurse into nested items.
+        if let Item::Macro(i) = i {
+            if i.mac.path.is_ident("macro_rules")
+                || i.mac.path.segments.last().unwrap().ident == "select"
+            {
+                self.visit_macro_mut(&mut i.mac);
+            }
+        }
+    }
+
+    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);
+        }
+    }
+}