Merge branch 'master' into rusty-hermit

1 files changed, 0 insertions, 1187 deletions

diff --git a/src/libsyntax/ext/base.rs b/src/libsyntax/ext/base.rs
deleted file mode 100644
index 583fb3f7701..00000000000
--- a/src/libsyntax/ext/base.rs
+++ /dev/null
@@ -1,1187 +0,0 @@
-use crate::ast::{self, NodeId, Attribute, Name, PatKind};
-use crate::attr::{self, HasAttrs, Stability, Deprecation};
-use crate::source_map::SourceMap;
-use crate::edition::Edition;
-use crate::ext::expand::{self, AstFragment, Invocation};
-use crate::ext::hygiene::ExpnId;
-use crate::mut_visit::{self, MutVisitor};
-use crate::parse::{self, parser, ParseSess, DirectoryOwnership};
-use crate::parse::token;
-use crate::ptr::P;
-use crate::symbol::{kw, sym, Ident, Symbol};
-use crate::{ThinVec, MACRO_ARGUMENTS};
-use crate::tokenstream::{self, TokenStream};
-use crate::visit::Visitor;
-
-use errors::{DiagnosticBuilder, DiagnosticId};
-use smallvec::{smallvec, SmallVec};
-use syntax_pos::{FileName, Span, MultiSpan, DUMMY_SP};
-use syntax_pos::hygiene::{AstPass, ExpnData, ExpnKind};
-
-use rustc_data_structures::fx::FxHashMap;
-use rustc_data_structures::sync::{self, Lrc};
-use std::iter;
-use std::path::PathBuf;
-use std::rc::Rc;
-use std::default::Default;
-
-pub use syntax_pos::hygiene::MacroKind;
-
-#[derive(Debug,Clone)]
-pub enum Annotatable {
-    Item(P<ast::Item>),
-    TraitItem(P<ast::TraitItem>),
-    ImplItem(P<ast::ImplItem>),
-    ForeignItem(P<ast::ForeignItem>),
-    Stmt(P<ast::Stmt>),
-    Expr(P<ast::Expr>),
-    Arm(ast::Arm),
-    Field(ast::Field),
-    FieldPat(ast::FieldPat),
-    GenericParam(ast::GenericParam),
-    Param(ast::Param),
-    StructField(ast::StructField),
-    Variant(ast::Variant),
-}
-
-impl HasAttrs for Annotatable {
-    fn attrs(&self) -> &[Attribute] {
-        match *self {
-            Annotatable::Item(ref item) => &item.attrs,
-            Annotatable::TraitItem(ref trait_item) => &trait_item.attrs,
-            Annotatable::ImplItem(ref impl_item) => &impl_item.attrs,
-            Annotatable::ForeignItem(ref foreign_item) => &foreign_item.attrs,
-            Annotatable::Stmt(ref stmt) => stmt.attrs(),
-            Annotatable::Expr(ref expr) => &expr.attrs,
-            Annotatable::Arm(ref arm) => &arm.attrs,
-            Annotatable::Field(ref field) => &field.attrs,
-            Annotatable::FieldPat(ref fp) => &fp.attrs,
-            Annotatable::GenericParam(ref gp) => &gp.attrs,
-            Annotatable::Param(ref p) => &p.attrs,
-            Annotatable::StructField(ref sf) => &sf.attrs,
-            Annotatable::Variant(ref v) => &v.attrs(),
-        }
-    }
-
-    fn visit_attrs<F: FnOnce(&mut Vec<Attribute>)>(&mut self, f: F) {
-        match self {
-            Annotatable::Item(item) => item.visit_attrs(f),
-            Annotatable::TraitItem(trait_item) => trait_item.visit_attrs(f),
-            Annotatable::ImplItem(impl_item) => impl_item.visit_attrs(f),
-            Annotatable::ForeignItem(foreign_item) => foreign_item.visit_attrs(f),
-            Annotatable::Stmt(stmt) => stmt.visit_attrs(f),
-            Annotatable::Expr(expr) => expr.visit_attrs(f),
-            Annotatable::Arm(arm) => arm.visit_attrs(f),
-            Annotatable::Field(field) => field.visit_attrs(f),
-            Annotatable::FieldPat(fp) => fp.visit_attrs(f),
-            Annotatable::GenericParam(gp) => gp.visit_attrs(f),
-            Annotatable::Param(p) => p.visit_attrs(f),
-            Annotatable::StructField(sf) => sf.visit_attrs(f),
-            Annotatable::Variant(v) => v.visit_attrs(f),
-        }
-    }
-}
-
-impl Annotatable {
-    pub fn span(&self) -> Span {
-        match *self {
-            Annotatable::Item(ref item) => item.span,
-            Annotatable::TraitItem(ref trait_item) => trait_item.span,
-            Annotatable::ImplItem(ref impl_item) => impl_item.span,
-            Annotatable::ForeignItem(ref foreign_item) => foreign_item.span,
-            Annotatable::Stmt(ref stmt) => stmt.span,
-            Annotatable::Expr(ref expr) => expr.span,
-            Annotatable::Arm(ref arm) => arm.span,
-            Annotatable::Field(ref field) => field.span,
-            Annotatable::FieldPat(ref fp) => fp.pat.span,
-            Annotatable::GenericParam(ref gp) => gp.ident.span,
-            Annotatable::Param(ref p) => p.span,
-            Annotatable::StructField(ref sf) => sf.span,
-            Annotatable::Variant(ref v) => v.span,
-        }
-    }
-
-    pub fn visit_with<'a, V: Visitor<'a>>(&'a self, visitor: &mut V) {
-        match self {
-            Annotatable::Item(item) => visitor.visit_item(item),
-            Annotatable::TraitItem(trait_item) => visitor.visit_trait_item(trait_item),
-            Annotatable::ImplItem(impl_item) => visitor.visit_impl_item(impl_item),
-            Annotatable::ForeignItem(foreign_item) => visitor.visit_foreign_item(foreign_item),
-            Annotatable::Stmt(stmt) => visitor.visit_stmt(stmt),
-            Annotatable::Expr(expr) => visitor.visit_expr(expr),
-            Annotatable::Arm(arm) => visitor.visit_arm(arm),
-            Annotatable::Field(field) => visitor.visit_field(field),
-            Annotatable::FieldPat(fp) => visitor.visit_field_pattern(fp),
-            Annotatable::GenericParam(gp) => visitor.visit_generic_param(gp),
-            Annotatable::Param(p) => visitor.visit_param(p),
-            Annotatable::StructField(sf) =>visitor.visit_struct_field(sf),
-            Annotatable::Variant(v) => visitor.visit_variant(v),
-        }
-    }
-
-    pub fn expect_item(self) -> P<ast::Item> {
-        match self {
-            Annotatable::Item(i) => i,
-            _ => panic!("expected Item")
-        }
-    }
-
-    pub fn map_item_or<F, G>(self, mut f: F, mut or: G) -> Annotatable
-        where F: FnMut(P<ast::Item>) -> P<ast::Item>,
-              G: FnMut(Annotatable) -> Annotatable
-    {
-        match self {
-            Annotatable::Item(i) => Annotatable::Item(f(i)),
-            _ => or(self)
-        }
-    }
-
-    pub fn expect_trait_item(self) -> ast::TraitItem {
-        match self {
-            Annotatable::TraitItem(i) => i.into_inner(),
-            _ => panic!("expected Item")
-        }
-    }
-
-    pub fn expect_impl_item(self) -> ast::ImplItem {
-        match self {
-            Annotatable::ImplItem(i) => i.into_inner(),
-            _ => panic!("expected Item")
-        }
-    }
-
-    pub fn expect_foreign_item(self) -> ast::ForeignItem {
-        match self {
-            Annotatable::ForeignItem(i) => i.into_inner(),
-            _ => panic!("expected foreign item")
-        }
-    }
-
-    pub fn expect_stmt(self) -> ast::Stmt {
-        match self {
-            Annotatable::Stmt(stmt) => stmt.into_inner(),
-            _ => panic!("expected statement"),
-        }
-    }
-
-    pub fn expect_expr(self) -> P<ast::Expr> {
-        match self {
-            Annotatable::Expr(expr) => expr,
-            _ => panic!("expected expression"),
-        }
-    }
-
-    pub fn expect_arm(self) -> ast::Arm {
-        match self {
-            Annotatable::Arm(arm) => arm,
-            _ => panic!("expected match arm")
-        }
-    }
-
-    pub fn expect_field(self) -> ast::Field {
-        match self {
-            Annotatable::Field(field) => field,
-            _ => panic!("expected field")
-        }
-    }
-
-    pub fn expect_field_pattern(self) -> ast::FieldPat {
-        match self {
-            Annotatable::FieldPat(fp) => fp,
-            _ => panic!("expected field pattern")
-        }
-    }
-
-    pub fn expect_generic_param(self) -> ast::GenericParam {
-        match self {
-            Annotatable::GenericParam(gp) => gp,
-            _ => panic!("expected generic parameter")
-        }
-    }
-
-    pub fn expect_param(self) -> ast::Param {
-        match self {
-            Annotatable::Param(param) => param,
-            _ => panic!("expected parameter")
-        }
-    }
-
-    pub fn expect_struct_field(self) -> ast::StructField {
-        match self {
-            Annotatable::StructField(sf) => sf,
-            _ => panic!("expected struct field")
-        }
-    }
-
-    pub fn expect_variant(self) -> ast::Variant {
-        match self {
-            Annotatable::Variant(v) => v,
-            _ => panic!("expected variant")
-        }
-    }
-
-    pub fn derive_allowed(&self) -> bool {
-        match *self {
-            Annotatable::Item(ref item) => match item.kind {
-                ast::ItemKind::Struct(..) |
-                ast::ItemKind::Enum(..) |
-                ast::ItemKind::Union(..) => true,
-                _ => false,
-            },
-            _ => false,
-        }
-    }
-}
-
-// `meta_item` is the annotation, and `item` is the item being modified.
-// FIXME Decorators should follow the same pattern too.
-pub trait MultiItemModifier {
-    fn expand(&self,
-              ecx: &mut ExtCtxt<'_>,
-              span: Span,
-              meta_item: &ast::MetaItem,
-              item: Annotatable)
-              -> Vec<Annotatable>;
-}
-
-impl<F, T> MultiItemModifier for F
-    where F: Fn(&mut ExtCtxt<'_>, Span, &ast::MetaItem, Annotatable) -> T,
-          T: Into<Vec<Annotatable>>,
-{
-    fn expand(&self,
-              ecx: &mut ExtCtxt<'_>,
-              span: Span,
-              meta_item: &ast::MetaItem,
-              item: Annotatable)
-              -> Vec<Annotatable> {
-        (*self)(ecx, span, meta_item, item).into()
-    }
-}
-
-impl Into<Vec<Annotatable>> for Annotatable {
-    fn into(self) -> Vec<Annotatable> {
-        vec![self]
-    }
-}
-
-pub trait ProcMacro {
-    fn expand<'cx>(&self,
-                   ecx: &'cx mut ExtCtxt<'_>,
-                   span: Span,
-                   ts: TokenStream)
-                   -> TokenStream;
-}
-
-impl<F> ProcMacro for F
-    where F: Fn(TokenStream) -> TokenStream
-{
-    fn expand<'cx>(&self,
-                   _ecx: &'cx mut ExtCtxt<'_>,
-                   _span: Span,
-                   ts: TokenStream)
-                   -> TokenStream {
-        // FIXME setup implicit context in TLS before calling self.
-        (*self)(ts)
-    }
-}
-
-pub trait AttrProcMacro {
-    fn expand<'cx>(&self,
-                   ecx: &'cx mut ExtCtxt<'_>,
-                   span: Span,
-                   annotation: TokenStream,
-                   annotated: TokenStream)
-                   -> TokenStream;
-}
-
-impl<F> AttrProcMacro for F
-    where F: Fn(TokenStream, TokenStream) -> TokenStream
-{
-    fn expand<'cx>(&self,
-                   _ecx: &'cx mut ExtCtxt<'_>,
-                   _span: Span,
-                   annotation: TokenStream,
-                   annotated: TokenStream)
-                   -> TokenStream {
-        // FIXME setup implicit context in TLS before calling self.
-        (*self)(annotation, annotated)
-    }
-}
-
-/// Represents a thing that maps token trees to Macro Results
-pub trait TTMacroExpander {
-    fn expand<'cx>(
-        &self,
-        ecx: &'cx mut ExtCtxt<'_>,
-        span: Span,
-        input: TokenStream,
-    ) -> Box<dyn MacResult+'cx>;
-}
-
-pub type MacroExpanderFn =
-    for<'cx> fn(&'cx mut ExtCtxt<'_>, Span, TokenStream)
-                -> Box<dyn MacResult+'cx>;
-
-impl<F> TTMacroExpander for F
-    where F: for<'cx> Fn(&'cx mut ExtCtxt<'_>, Span, TokenStream)
-    -> Box<dyn MacResult+'cx>
-{
-    fn expand<'cx>(
-        &self,
-        ecx: &'cx mut ExtCtxt<'_>,
-        span: Span,
-        mut input: TokenStream,
-    ) -> Box<dyn MacResult+'cx> {
-        struct AvoidInterpolatedIdents;
-
-        impl MutVisitor for AvoidInterpolatedIdents {
-            fn visit_tt(&mut self, tt: &mut tokenstream::TokenTree) {
-                if let tokenstream::TokenTree::Token(token) = tt {
-                    if let token::Interpolated(nt) = &token.kind {
-                        if let token::NtIdent(ident, is_raw) = **nt {
-                            *tt = tokenstream::TokenTree::token(
-                                token::Ident(ident.name, is_raw), ident.span
-                            );
-                        }
-                    }
-                }
-                mut_visit::noop_visit_tt(tt, self)
-            }
-
-            fn visit_mac(&mut self, mac: &mut ast::Mac) {
-                mut_visit::noop_visit_mac(mac, self)
-            }
-        }
-        AvoidInterpolatedIdents.visit_tts(&mut input);
-        (*self)(ecx, span, input)
-    }
-}
-
-// Use a macro because forwarding to a simple function has type system issues
-macro_rules! make_stmts_default {
-    ($me:expr) => {
-        $me.make_expr().map(|e| smallvec![ast::Stmt {
-            id: ast::DUMMY_NODE_ID,
-            span: e.span,
-            kind: ast::StmtKind::Expr(e),
-        }])
-    }
-}
-
-/// The result of a macro expansion. The return values of the various
-/// methods are spliced into the AST at the callsite of the macro.
-pub trait MacResult {
-    /// Creates an expression.
-    fn make_expr(self: Box<Self>) -> Option<P<ast::Expr>> {
-        None
-    }
-    /// Creates zero or more items.
-    fn make_items(self: Box<Self>) -> Option<SmallVec<[P<ast::Item>; 1]>> {
-        None
-    }
-
-    /// Creates zero or more impl items.
-    fn make_impl_items(self: Box<Self>) -> Option<SmallVec<[ast::ImplItem; 1]>> {
-        None
-    }
-
-    /// Creates zero or more trait items.
-    fn make_trait_items(self: Box<Self>) -> Option<SmallVec<[ast::TraitItem; 1]>> {
-        None
-    }
-
-    /// Creates zero or more items in an `extern {}` block
-    fn make_foreign_items(self: Box<Self>) -> Option<SmallVec<[ast::ForeignItem; 1]>> { None }
-
-    /// Creates a pattern.
-    fn make_pat(self: Box<Self>) -> Option<P<ast::Pat>> {
-        None
-    }
-
-    /// Creates zero or more statements.
-    ///
-    /// By default this attempts to create an expression statement,
-    /// returning None if that fails.
-    fn make_stmts(self: Box<Self>) -> Option<SmallVec<[ast::Stmt; 1]>> {
-        make_stmts_default!(self)
-    }
-
-    fn make_ty(self: Box<Self>) -> Option<P<ast::Ty>> {
-        None
-    }
-
-    fn make_arms(self: Box<Self>) -> Option<SmallVec<[ast::Arm; 1]>> {
-        None
-    }
-
-    fn make_fields(self: Box<Self>) -> Option<SmallVec<[ast::Field; 1]>> {
-        None
-    }
-
-    fn make_field_patterns(self: Box<Self>) -> Option<SmallVec<[ast::FieldPat; 1]>> {
-        None
-    }
-
-    fn make_generic_params(self: Box<Self>) -> Option<SmallVec<[ast::GenericParam; 1]>> {
-        None
-    }
-
-    fn make_params(self: Box<Self>) -> Option<SmallVec<[ast::Param; 1]>> {
-        None
-    }
-
-    fn make_struct_fields(self: Box<Self>) -> Option<SmallVec<[ast::StructField; 1]>> {
-        None
-    }
-
-    fn make_variants(self: Box<Self>) -> Option<SmallVec<[ast::Variant; 1]>> {
-        None
-    }
-}
-
-macro_rules! make_MacEager {
-    ( $( $fld:ident: $t:ty, )* ) => {
-        /// `MacResult` implementation for the common case where you've already
-        /// built each form of AST that you might return.
-        #[derive(Default)]
-        pub struct MacEager {
-            $(
-                pub $fld: Option<$t>,
-            )*
-        }
-
-        impl MacEager {
-            $(
-                pub fn $fld(v: $t) -> Box<dyn MacResult> {
-                    Box::new(MacEager {
-                        $fld: Some(v),
-                        ..Default::default()
-                    })
-                }
-            )*
-        }
-    }
-}
-
-make_MacEager! {
-    expr: P<ast::Expr>,
-    pat: P<ast::Pat>,
-    items: SmallVec<[P<ast::Item>; 1]>,
-    impl_items: SmallVec<[ast::ImplItem; 1]>,
-    trait_items: SmallVec<[ast::TraitItem; 1]>,
-    foreign_items: SmallVec<[ast::ForeignItem; 1]>,
-    stmts: SmallVec<[ast::Stmt; 1]>,
-    ty: P<ast::Ty>,
-}
-
-impl MacResult for MacEager {
-    fn make_expr(self: Box<Self>) -> Option<P<ast::Expr>> {
-        self.expr
-    }
-
-    fn make_items(self: Box<Self>) -> Option<SmallVec<[P<ast::Item>; 1]>> {
-        self.items
-    }
-
-    fn make_impl_items(self: Box<Self>) -> Option<SmallVec<[ast::ImplItem; 1]>> {
-        self.impl_items
-    }
-
-    fn make_trait_items(self: Box<Self>) -> Option<SmallVec<[ast::TraitItem; 1]>> {
-        self.trait_items
-    }
-
-    fn make_foreign_items(self: Box<Self>) -> Option<SmallVec<[ast::ForeignItem; 1]>> {
-        self.foreign_items
-    }
-
-    fn make_stmts(self: Box<Self>) -> Option<SmallVec<[ast::Stmt; 1]>> {
-        match self.stmts.as_ref().map_or(0, |s| s.len()) {
-            0 => make_stmts_default!(self),
-            _ => self.stmts,
-        }
-    }
-
-    fn make_pat(self: Box<Self>) -> Option<P<ast::Pat>> {
-        if let Some(p) = self.pat {
-            return Some(p);
-        }
-        if let Some(e) = self.expr {
-            if let ast::ExprKind::Lit(_) = e.kind {
-                return Some(P(ast::Pat {
-                    id: ast::DUMMY_NODE_ID,
-                    span: e.span,
-                    kind: PatKind::Lit(e),
-                }));
-            }
-        }
-        None
-    }
-
-    fn make_ty(self: Box<Self>) -> Option<P<ast::Ty>> {
-        self.ty
-    }
-}
-
-/// Fill-in macro expansion result, to allow compilation to continue
-/// after hitting errors.
-#[derive(Copy, Clone)]
-pub struct DummyResult {
-    is_error: bool,
-    span: Span,
-}
-
-impl DummyResult {
-    /// Creates a default MacResult that can be anything.
-    ///
-    /// Use this as a return value after hitting any errors and
-    /// calling `span_err`.
-    pub fn any(span: Span) -> Box<dyn MacResult+'static> {
-        Box::new(DummyResult { is_error: true, span })
-    }
-
-    /// Same as `any`, but must be a valid fragment, not error.
-    pub fn any_valid(span: Span) -> Box<dyn MacResult+'static> {
-        Box::new(DummyResult { is_error: false, span })
-    }
-
-    /// A plain dummy expression.
-    pub fn raw_expr(sp: Span, is_error: bool) -> P<ast::Expr> {
-        P(ast::Expr {
-            id: ast::DUMMY_NODE_ID,
-            kind: if is_error { ast::ExprKind::Err } else { ast::ExprKind::Tup(Vec::new()) },
-            span: sp,
-            attrs: ThinVec::new(),
-        })
-    }
-
-    /// A plain dummy pattern.
-    pub fn raw_pat(sp: Span) -> ast::Pat {
-        ast::Pat {
-            id: ast::DUMMY_NODE_ID,
-            kind: PatKind::Wild,
-            span: sp,
-        }
-    }
-
-    /// A plain dummy type.
-    pub fn raw_ty(sp: Span, is_error: bool) -> P<ast::Ty> {
-        P(ast::Ty {
-            id: ast::DUMMY_NODE_ID,
-            kind: if is_error { ast::TyKind::Err } else { ast::TyKind::Tup(Vec::new()) },
-            span: sp
-        })
-    }
-}
-
-impl MacResult for DummyResult {
-    fn make_expr(self: Box<DummyResult>) -> Option<P<ast::Expr>> {
-        Some(DummyResult::raw_expr(self.span, self.is_error))
-    }
-
-    fn make_pat(self: Box<DummyResult>) -> Option<P<ast::Pat>> {
-        Some(P(DummyResult::raw_pat(self.span)))
-    }
-
-    fn make_items(self: Box<DummyResult>) -> Option<SmallVec<[P<ast::Item>; 1]>> {
-        Some(SmallVec::new())
-    }
-
-    fn make_impl_items(self: Box<DummyResult>) -> Option<SmallVec<[ast::ImplItem; 1]>> {
-        Some(SmallVec::new())
-    }
-
-    fn make_trait_items(self: Box<DummyResult>) -> Option<SmallVec<[ast::TraitItem; 1]>> {
-        Some(SmallVec::new())
-    }
-
-    fn make_foreign_items(self: Box<Self>) -> Option<SmallVec<[ast::ForeignItem; 1]>> {
-        Some(SmallVec::new())
-    }
-
-    fn make_stmts(self: Box<DummyResult>) -> Option<SmallVec<[ast::Stmt; 1]>> {
-        Some(smallvec![ast::Stmt {
-            id: ast::DUMMY_NODE_ID,
-            kind: ast::StmtKind::Expr(DummyResult::raw_expr(self.span, self.is_error)),
-            span: self.span,
-        }])
-    }
-
-    fn make_ty(self: Box<DummyResult>) -> Option<P<ast::Ty>> {
-        Some(DummyResult::raw_ty(self.span, self.is_error))
-    }
-
-    fn make_arms(self: Box<DummyResult>) -> Option<SmallVec<[ast::Arm; 1]>> {
-       Some(SmallVec::new())
-    }
-
-    fn make_fields(self: Box<DummyResult>) -> Option<SmallVec<[ast::Field; 1]>> {
-        Some(SmallVec::new())
-    }
-
-    fn make_field_patterns(self: Box<DummyResult>) -> Option<SmallVec<[ast::FieldPat; 1]>> {
-        Some(SmallVec::new())
-    }
-
-    fn make_generic_params(self: Box<DummyResult>) -> Option<SmallVec<[ast::GenericParam; 1]>> {
-        Some(SmallVec::new())
-    }
-
-    fn make_params(self: Box<DummyResult>) -> Option<SmallVec<[ast::Param; 1]>> {
-        Some(SmallVec::new())
-    }
-
-    fn make_struct_fields(self: Box<DummyResult>) -> Option<SmallVec<[ast::StructField; 1]>> {
-        Some(SmallVec::new())
-    }
-
-    fn make_variants(self: Box<DummyResult>) -> Option<SmallVec<[ast::Variant; 1]>> {
-        Some(SmallVec::new())
-    }
-}
-
-/// A syntax extension kind.
-pub enum SyntaxExtensionKind {
-    /// A token-based function-like macro.
-    Bang(
-        /// An expander with signature TokenStream -> TokenStream.
-        Box<dyn ProcMacro + sync::Sync + sync::Send>,
-    ),
-
-    /// An AST-based function-like macro.
-    LegacyBang(
-        /// An expander with signature TokenStream -> AST.
-        Box<dyn TTMacroExpander + sync::Sync + sync::Send>,
-    ),
-
-    /// A token-based attribute macro.
-    Attr(
-        /// An expander with signature (TokenStream, TokenStream) -> TokenStream.
-        /// The first TokenSteam is the attribute itself, the second is the annotated item.
-        /// The produced TokenSteam replaces the input TokenSteam.
-        Box<dyn AttrProcMacro + sync::Sync + sync::Send>,
-    ),
-
-    /// An AST-based attribute macro.
-    LegacyAttr(
-        /// An expander with signature (AST, AST) -> AST.
-        /// The first AST fragment is the attribute itself, the second is the annotated item.
-        /// The produced AST fragment replaces the input AST fragment.
-        Box<dyn MultiItemModifier + sync::Sync + sync::Send>,
-    ),
-
-    /// A trivial attribute "macro" that does nothing,
-    /// only keeps the attribute and marks it as inert,
-    /// thus making it ineligible for further expansion.
-    NonMacroAttr {
-        /// Suppresses the `unused_attributes` lint for this attribute.
-        mark_used: bool,
-    },
-
-    /// A token-based derive macro.
-    Derive(
-        /// An expander with signature TokenStream -> TokenStream (not yet).
-        /// The produced TokenSteam is appended to the input TokenSteam.
-        Box<dyn MultiItemModifier + sync::Sync + sync::Send>,
-    ),
-
-    /// An AST-based derive macro.
-    LegacyDerive(
-        /// An expander with signature AST -> AST.
-        /// The produced AST fragment is appended to the input AST fragment.
-        Box<dyn MultiItemModifier + sync::Sync + sync::Send>,
-    ),
-}
-
-/// A struct representing a macro definition in "lowered" form ready for expansion.
-pub struct SyntaxExtension {
-    /// A syntax extension kind.
-    pub kind: SyntaxExtensionKind,
-    /// Span of the macro definition.
-    pub span: Span,
-    /// Whitelist of unstable features that are treated as stable inside this macro.
-    pub allow_internal_unstable: Option<Lrc<[Symbol]>>,
-    /// Suppresses the `unsafe_code` lint for code produced by this macro.
-    pub allow_internal_unsafe: bool,
-    /// Enables the macro helper hack (`ident!(...)` -> `$crate::ident!(...)`) for this macro.
-    pub local_inner_macros: bool,
-    /// The macro's stability info.
-    pub stability: Option<Stability>,
-    /// The macro's deprecation info.
-    pub deprecation: Option<Deprecation>,
-    /// Names of helper attributes registered by this macro.
-    pub helper_attrs: Vec<Symbol>,
-    /// Edition of the crate in which this macro is defined.
-    pub edition: Edition,
-    /// Built-in macros have a couple of special properties like availability
-    /// in `#[no_implicit_prelude]` modules, so we have to keep this flag.
-    pub is_builtin: bool,
-    /// We have to identify macros providing a `Copy` impl early for compatibility reasons.
-    pub is_derive_copy: bool,
-}
-
-impl SyntaxExtension {
-    /// Returns which kind of macro calls this syntax extension.
-    pub fn macro_kind(&self) -> MacroKind {
-        match self.kind {
-            SyntaxExtensionKind::Bang(..) |
-            SyntaxExtensionKind::LegacyBang(..) => MacroKind::Bang,
-            SyntaxExtensionKind::Attr(..) |
-            SyntaxExtensionKind::LegacyAttr(..) |
-            SyntaxExtensionKind::NonMacroAttr { .. } => MacroKind::Attr,
-            SyntaxExtensionKind::Derive(..) |
-            SyntaxExtensionKind::LegacyDerive(..) => MacroKind::Derive,
-        }
-    }
-
-    /// Constructs a syntax extension with default properties.
-    pub fn default(kind: SyntaxExtensionKind, edition: Edition) -> SyntaxExtension {
-        SyntaxExtension {
-            span: DUMMY_SP,
-            allow_internal_unstable: None,
-            allow_internal_unsafe: false,
-            local_inner_macros: false,
-            stability: None,
-            deprecation: None,
-            helper_attrs: Vec::new(),
-            edition,
-            is_builtin: false,
-            is_derive_copy: false,
-            kind,
-        }
-    }
-
-    /// Constructs a syntax extension with the given properties
-    /// and other properties converted from attributes.
-    pub fn new(
-        sess: &ParseSess,
-        kind: SyntaxExtensionKind,
-        span: Span,
-        helper_attrs: Vec<Symbol>,
-        edition: Edition,
-        name: Name,
-        attrs: &[ast::Attribute],
-    ) -> SyntaxExtension {
-        let allow_internal_unstable = attr::allow_internal_unstable(
-            &attrs, &sess.span_diagnostic,
-        ).map(|features| features.collect::<Vec<Symbol>>().into());
-
-        let mut local_inner_macros = false;
-        if let Some(macro_export) = attr::find_by_name(attrs, sym::macro_export) {
-            if let Some(l) = macro_export.meta_item_list() {
-                local_inner_macros = attr::list_contains_name(&l, sym::local_inner_macros);
-            }
-        }
-
-        let is_builtin = attr::contains_name(attrs, sym::rustc_builtin_macro);
-
-        SyntaxExtension {
-            kind,
-            span,
-            allow_internal_unstable,
-            allow_internal_unsafe: attr::contains_name(attrs, sym::allow_internal_unsafe),
-            local_inner_macros,
-            stability: attr::find_stability(&sess, attrs, span),
-            deprecation: attr::find_deprecation(&sess, attrs, span),
-            helper_attrs,
-            edition,
-            is_builtin,
-            is_derive_copy: is_builtin && name == sym::Copy,
-        }
-    }
-
-    pub fn dummy_bang(edition: Edition) -> SyntaxExtension {
-        fn expander<'cx>(_: &'cx mut ExtCtxt<'_>, span: Span, _: TokenStream)
-                         -> Box<dyn MacResult + 'cx> {
-            DummyResult::any(span)
-        }
-        SyntaxExtension::default(SyntaxExtensionKind::LegacyBang(Box::new(expander)), edition)
-    }
-
-    pub fn dummy_derive(edition: Edition) -> SyntaxExtension {
-        fn expander(_: &mut ExtCtxt<'_>, _: Span, _: &ast::MetaItem, _: Annotatable)
-                    -> Vec<Annotatable> {
-            Vec::new()
-        }
-        SyntaxExtension::default(SyntaxExtensionKind::Derive(Box::new(expander)), edition)
-    }
-
-    pub fn non_macro_attr(mark_used: bool, edition: Edition) -> SyntaxExtension {
-        SyntaxExtension::default(SyntaxExtensionKind::NonMacroAttr { mark_used }, edition)
-    }
-
-    pub fn expn_data(&self, parent: ExpnId, call_site: Span, descr: Symbol) -> ExpnData {
-        ExpnData {
-            kind: ExpnKind::Macro(self.macro_kind(), descr),
-            parent,
-            call_site,
-            def_site: self.span,
-            allow_internal_unstable: self.allow_internal_unstable.clone(),
-            allow_internal_unsafe: self.allow_internal_unsafe,
-            local_inner_macros: self.local_inner_macros,
-            edition: self.edition,
-        }
-    }
-}
-
-pub type NamedSyntaxExtension = (Name, SyntaxExtension);
-
-/// Result of resolving a macro invocation.
-pub enum InvocationRes {
-    Single(Lrc<SyntaxExtension>),
-    DeriveContainer(Vec<Lrc<SyntaxExtension>>),
-}
-
-/// Error type that denotes indeterminacy.
-pub struct Indeterminate;
-
-bitflags::bitflags! {
-    /// Built-in derives that need some extra tracking beyond the usual macro functionality.
-    #[derive(Default)]
-    pub struct SpecialDerives: u8 {
-        const PARTIAL_EQ = 1 << 0;
-        const EQ         = 1 << 1;
-        const COPY       = 1 << 2;
-    }
-}
-
-pub trait Resolver {
-    fn next_node_id(&mut self) -> NodeId;
-
-    fn resolve_dollar_crates(&mut self);
-    fn visit_ast_fragment_with_placeholders(&mut self, expn_id: ExpnId, fragment: &AstFragment,
-                                            extra_placeholders: &[NodeId]);
-    fn register_builtin_macro(&mut self, ident: ast::Ident, ext: SyntaxExtension);
-
-    fn expansion_for_ast_pass(
-        &mut self,
-        call_site: Span,
-        pass: AstPass,
-        features: &[Symbol],
-        parent_module_id: Option<NodeId>,
-    ) -> ExpnId;
-
-    fn resolve_imports(&mut self);
-
-    fn resolve_macro_invocation(
-        &mut self, invoc: &Invocation, eager_expansion_root: ExpnId, force: bool
-    ) -> Result<InvocationRes, Indeterminate>;
-
-    fn check_unused_macros(&self);
-
-    fn has_derives(&self, expn_id: ExpnId, derives: SpecialDerives) -> bool;
-    fn add_derives(&mut self, expn_id: ExpnId, derives: SpecialDerives);
-}
-
-#[derive(Clone)]
-pub struct ModuleData {
-    pub mod_path: Vec<ast::Ident>,
-    pub directory: PathBuf,
-}
-
-#[derive(Clone)]
-pub struct ExpansionData {
-    pub id: ExpnId,
-    pub depth: usize,
-    pub module: Rc<ModuleData>,
-    pub directory_ownership: DirectoryOwnership,
-    pub prior_type_ascription: Option<(Span, bool)>,
-}
-
-/// One of these is made during expansion and incrementally updated as we go;
-/// when a macro expansion occurs, the resulting nodes have the `backtrace()
-/// -> expn_data` of their expansion context stored into their span.
-pub struct ExtCtxt<'a> {
-    pub parse_sess: &'a parse::ParseSess,
-    pub ecfg: expand::ExpansionConfig<'a>,
-    pub root_path: PathBuf,
-    pub resolver: &'a mut dyn Resolver,
-    pub current_expansion: ExpansionData,
-    pub expansions: FxHashMap<Span, Vec<String>>,
-}
-
-impl<'a> ExtCtxt<'a> {
-    pub fn new(parse_sess: &'a parse::ParseSess,
-               ecfg: expand::ExpansionConfig<'a>,
-               resolver: &'a mut dyn Resolver)
-               -> ExtCtxt<'a> {
-        ExtCtxt {
-            parse_sess,
-            ecfg,
-            root_path: PathBuf::new(),
-            resolver,
-            current_expansion: ExpansionData {
-                id: ExpnId::root(),
-                depth: 0,
-                module: Rc::new(ModuleData { mod_path: Vec::new(), directory: PathBuf::new() }),
-                directory_ownership: DirectoryOwnership::Owned { relative: None },
-                prior_type_ascription: None,
-            },
-            expansions: FxHashMap::default(),
-        }
-    }
-
-    /// Returns a `Folder` for deeply expanding all macros in an AST node.
-    pub fn expander<'b>(&'b mut self) -> expand::MacroExpander<'b, 'a> {
-        expand::MacroExpander::new(self, false)
-    }
-
-    /// Returns a `Folder` that deeply expands all macros and assigns all `NodeId`s in an AST node.
-    /// Once `NodeId`s are assigned, the node may not be expanded, removed, or otherwise modified.
-    pub fn monotonic_expander<'b>(&'b mut self) -> expand::MacroExpander<'b, 'a> {
-        expand::MacroExpander::new(self, true)
-    }
-    pub fn new_parser_from_tts(&self, stream: TokenStream) -> parser::Parser<'a> {
-        parse::stream_to_parser(self.parse_sess, stream, MACRO_ARGUMENTS)
-    }
-    pub fn source_map(&self) -> &'a SourceMap { self.parse_sess.source_map() }
-    pub fn parse_sess(&self) -> &'a parse::ParseSess { self.parse_sess }
-    pub fn cfg(&self) -> &ast::CrateConfig { &self.parse_sess.config }
-    pub fn call_site(&self) -> Span {
-        self.current_expansion.id.expn_data().call_site
-    }
-
-    /// Equivalent of `Span::def_site` from the proc macro API,
-    /// except that the location is taken from the span passed as an argument.
-    pub fn with_def_site_ctxt(&self, span: Span) -> Span {
-        span.with_def_site_ctxt(self.current_expansion.id)
-    }
-
-    /// Equivalent of `Span::call_site` from the proc macro API,
-    /// except that the location is taken from the span passed as an argument.
-    pub fn with_call_site_ctxt(&self, span: Span) -> Span {
-        span.with_call_site_ctxt(self.current_expansion.id)
-    }
-
-    /// Equivalent of `Span::mixed_site` from the proc macro API,
-    /// except that the location is taken from the span passed as an argument.
-    pub fn with_mixed_site_ctxt(&self, span: Span) -> Span {
-        span.with_mixed_site_ctxt(self.current_expansion.id)
-    }
-
-    /// Returns span for the macro which originally caused the current expansion to happen.
-    ///
-    /// Stops backtracing at include! boundary.
-    pub fn expansion_cause(&self) -> Option<Span> {
-        let mut expn_id = self.current_expansion.id;
-        let mut last_macro = None;
-        loop {
-            let expn_data = expn_id.expn_data();
-            // Stop going up the backtrace once include! is encountered
-            if expn_data.is_root() || expn_data.kind.descr() == sym::include {
-                break;
-            }
-            expn_id = expn_data.call_site.ctxt().outer_expn();
-            last_macro = Some(expn_data.call_site);
-        }
-        last_macro
-    }
-
-    pub fn struct_span_warn<S: Into<MultiSpan>>(&self,
-                                                sp: S,
-                                                msg: &str)
-                                                -> DiagnosticBuilder<'a> {
-        self.parse_sess.span_diagnostic.struct_span_warn(sp, msg)
-    }
-    pub fn struct_span_err<S: Into<MultiSpan>>(&self,
-                                               sp: S,
-                                               msg: &str)
-                                               -> DiagnosticBuilder<'a> {
-        self.parse_sess.span_diagnostic.struct_span_err(sp, msg)
-    }
-    pub fn struct_span_fatal<S: Into<MultiSpan>>(&self,
-                                                 sp: S,
-                                                 msg: &str)
-                                                 -> DiagnosticBuilder<'a> {
-        self.parse_sess.span_diagnostic.struct_span_fatal(sp, msg)
-    }
-
-    /// Emit `msg` attached to `sp`, and stop compilation immediately.
-    ///
-    /// `span_err` should be strongly preferred where-ever possible:
-    /// this should *only* be used when:
-    ///
-    /// - continuing has a high risk of flow-on errors (e.g., errors in
-    ///   declaring a macro would cause all uses of that macro to
-    ///   complain about "undefined macro"), or
-    /// - there is literally nothing else that can be done (however,
-    ///   in most cases one can construct a dummy expression/item to
-    ///   substitute; we never hit resolve/type-checking so the dummy
-    ///   value doesn't have to match anything)
-    pub fn span_fatal<S: Into<MultiSpan>>(&self, sp: S, msg: &str) -> ! {
-        self.parse_sess.span_diagnostic.span_fatal(sp, msg).raise();
-    }
-
-    /// Emit `msg` attached to `sp`, without immediately stopping
-    /// compilation.
-    ///
-    /// Compilation will be stopped in the near future (at the end of
-    /// the macro expansion phase).
-    pub fn span_err<S: Into<MultiSpan>>(&self, sp: S, msg: &str) {
-        self.parse_sess.span_diagnostic.span_err(sp, msg);
-    }
-    pub fn span_err_with_code<S: Into<MultiSpan>>(&self, sp: S, msg: &str, code: DiagnosticId) {
-        self.parse_sess.span_diagnostic.span_err_with_code(sp, msg, code);
-    }
-    pub fn span_warn<S: Into<MultiSpan>>(&self, sp: S, msg: &str) {
-        self.parse_sess.span_diagnostic.span_warn(sp, msg);
-    }
-    pub fn span_bug<S: Into<MultiSpan>>(&self, sp: S, msg: &str) -> ! {
-        self.parse_sess.span_diagnostic.span_bug(sp, msg);
-    }
-    pub fn trace_macros_diag(&mut self) {
-        for (sp, notes) in self.expansions.iter() {
-            let mut db = self.parse_sess.span_diagnostic.span_note_diag(*sp, "trace_macro");
-            for note in notes {
-                db.note(note);
-            }
-            db.emit();
-        }
-        // Fixme: does this result in errors?
-        self.expansions.clear();
-    }
-    pub fn bug(&self, msg: &str) -> ! {
-        self.parse_sess.span_diagnostic.bug(msg);
-    }
-    pub fn trace_macros(&self) -> bool {
-        self.ecfg.trace_mac
-    }
-    pub fn set_trace_macros(&mut self, x: bool) {
-        self.ecfg.trace_mac = x
-    }
-    pub fn ident_of(&self, st: &str, sp: Span) -> ast::Ident {
-        ast::Ident::from_str_and_span(st, sp)
-    }
-    pub fn std_path(&self, components: &[Symbol]) -> Vec<ast::Ident> {
-        let def_site = self.with_def_site_ctxt(DUMMY_SP);
-        iter::once(Ident::new(kw::DollarCrate, def_site))
-            .chain(components.iter().map(|&s| Ident::with_dummy_span(s)))
-            .collect()
-    }
-    pub fn name_of(&self, st: &str) -> ast::Name {
-        Symbol::intern(st)
-    }
-
-    pub fn check_unused_macros(&self) {
-        self.resolver.check_unused_macros();
-    }
-
-    /// Resolves a path mentioned inside Rust code.
-    ///
-    /// This unifies the logic used for resolving `include_X!`, and `#[doc(include)]` file paths.
-    ///
-    /// Returns an absolute path to the file that `path` refers to.
-    pub fn resolve_path(&self, path: impl Into<PathBuf>, span: Span) -> PathBuf {
-        let path = path.into();
-
-        // Relative paths are resolved relative to the file in which they are found
-        // after macro expansion (that is, they are unhygienic).
-        if !path.is_absolute() {
-            let callsite = span.source_callsite();
-            let mut result = match self.source_map().span_to_unmapped_path(callsite) {
-                FileName::Real(path) => path,
-                FileName::DocTest(path, _) => path,
-                other => panic!("cannot resolve relative path in non-file source `{}`", other),
-            };
-            result.pop();
-            result.push(path);
-            result
-        } else {
-            path
-        }
-    }
-}
-
-/// Extracts a string literal from the macro expanded version of `expr`,
-/// emitting `err_msg` if `expr` is not a string literal. This does not stop
-/// compilation on error, merely emits a non-fatal error and returns `None`.
-pub fn expr_to_spanned_string<'a>(
-    cx: &'a mut ExtCtxt<'_>,
-    expr: P<ast::Expr>,
-    err_msg: &str,
-) -> Result<(Symbol, ast::StrStyle, Span), Option<DiagnosticBuilder<'a>>> {
-    // Perform eager expansion on the expression.
-    // We want to be able to handle e.g., `concat!("foo", "bar")`.
-    let expr = cx.expander().fully_expand_fragment(AstFragment::Expr(expr)).make_expr();
-
-    Err(match expr.kind {
-        ast::ExprKind::Lit(ref l) => match l.kind {
-            ast::LitKind::Str(s, style) => return Ok((s, style, expr.span)),
-            ast::LitKind::Err(_) => None,
-            _ => Some(cx.struct_span_err(l.span, err_msg))
-        },
-        ast::ExprKind::Err => None,
-        _ => Some(cx.struct_span_err(expr.span, err_msg))
-    })
-}
-
-pub fn expr_to_string(cx: &mut ExtCtxt<'_>, expr: P<ast::Expr>, err_msg: &str)
-                      -> Option<(Symbol, ast::StrStyle)> {
-    expr_to_spanned_string(cx, expr, err_msg)
-        .map_err(|err| err.map(|mut err| err.emit()))
-        .ok()
-        .map(|(symbol, style, _)| (symbol, style))
-}
-
-/// Non-fatally assert that `tts` is empty. Note that this function
-/// returns even when `tts` is non-empty, macros that *need* to stop
-/// compilation should call
-/// `cx.parse_sess.span_diagnostic.abort_if_errors()` (this should be
-/// done as rarely as possible).
-pub fn check_zero_tts(cx: &ExtCtxt<'_>,
-                      sp: Span,
-                      tts: TokenStream,
-                      name: &str) {
-    if !tts.is_empty() {
-        cx.span_err(sp, &format!("{} takes no arguments", name));
-    }
-}
-
-/// Interpreting `tts` as a comma-separated sequence of expressions,
-/// expect exactly one string literal, or emit an error and return `None`.
-pub fn get_single_str_from_tts(cx: &mut ExtCtxt<'_>,
-                               sp: Span,
-                               tts: TokenStream,
-                               name: &str)
-                               -> Option<String> {
-    let mut p = cx.new_parser_from_tts(tts);
-    if p.token == token::Eof {
-        cx.span_err(sp, &format!("{} takes 1 argument", name));
-        return None
-    }
-    let ret = panictry!(p.parse_expr());
-    let _ = p.eat(&token::Comma);
-
-    if p.token != token::Eof {
-        cx.span_err(sp, &format!("{} takes 1 argument", name));
-    }
-    expr_to_string(cx, ret, "argument must be a string literal").map(|(s, _)| {
-        s.to_string()
-    })
-}
-
-/// Extracts comma-separated expressions from `tts`. If there is a
-/// parsing error, emit a non-fatal error and return `None`.
-pub fn get_exprs_from_tts(cx: &mut ExtCtxt<'_>,
-                          sp: Span,
-                          tts: TokenStream) -> Option<Vec<P<ast::Expr>>> {
-    let mut p = cx.new_parser_from_tts(tts);
-    let mut es = Vec::new();
-    while p.token != token::Eof {
-        let expr = panictry!(p.parse_expr());
-
-        // Perform eager expansion on the expression.
-        // We want to be able to handle e.g., `concat!("foo", "bar")`.
-        let expr = cx.expander().fully_expand_fragment(AstFragment::Expr(expr)).make_expr();
-
-        es.push(expr);
-        if p.eat(&token::Comma) {
-            continue;
-        }
-        if p.token != token::Eof {
-            cx.span_err(sp, "expected token: `,`");
-            return None;
-        }
-    }
-    Some(es)
-}