syntax: Factor out common fields from SyntaxExtension variants

src/doc/unstable-book/src/language-features/plugin.md

@@ -132,7 +132,7 @@ The advantages over a simple `fn(&str) -> u32` are:
 In addition to procedural macros, you can define new
 [`derive`](../../reference/attributes/derive.md)-like attributes and other kinds
 of extensions.  See `Registry::register_syntax_extension` and the
-`SyntaxExtension` enum.  For a more involved macro example, see
+`SyntaxExtension` struct.  For a more involved macro example, see
 [`regex_macros`](https://github.com/rust-lang/regex/blob/master/regex_macros/src/lib.rs).
 
 

src/librustc/hir/lowering.rs

@@ -62,14 +62,14 @@ use syntax::errors;
 use syntax::ext::hygiene::{Mark, SyntaxContext};
 use syntax::print::pprust;
 use syntax::ptr::P;
-use syntax::source_map::{self, respan, CompilerDesugaringKind, Spanned};
+use syntax::source_map::{self, respan, ExpnInfo, CompilerDesugaringKind, Spanned};
 use syntax::source_map::CompilerDesugaringKind::IfTemporary;
 use syntax::std_inject;
 use syntax::symbol::{kw, sym, Symbol};
 use syntax::tokenstream::{TokenStream, TokenTree};
 use syntax::parse::token::{self, Token};
 use syntax::visit::{self, Visitor};
-use syntax_pos::{DUMMY_SP, edition, Span};
+use syntax_pos::{DUMMY_SP, Span};
 
 const HIR_ID_COUNTER_LOCKED: u32 = 0xFFFFFFFF;
 
@@ -142,6 +142,9 @@ pub struct LoweringContext<'a> {
     current_hir_id_owner: Vec<(DefIndex, u32)>,
     item_local_id_counters: NodeMap<u32>,
     node_id_to_hir_id: IndexVec<NodeId, hir::HirId>,
+
+    allow_try_trait: Option<Lrc<[Symbol]>>,
+    allow_gen_future: Option<Lrc<[Symbol]>>,
 }
 
 pub trait Resolver {
@@ -267,6 +270,8 @@ pub fn lower_crate(
         lifetimes_to_define: Vec::new(),
         is_collecting_in_band_lifetimes: false,
         in_scope_lifetimes: Vec::new(),
+        allow_try_trait: Some([sym::try_trait][..].into()),
+        allow_gen_future: Some([sym::gen_future][..].into()),
     }.lower_crate(krate)
 }
 
@@ -848,14 +853,10 @@ impl<'a> LoweringContext<'a> {
         allow_internal_unstable: Option<Lrc<[Symbol]>>,
     ) -> Span {
         let mark = Mark::fresh(Mark::root());
-        mark.set_expn_info(source_map::ExpnInfo {
-            call_site: span,
+        mark.set_expn_info(ExpnInfo {
             def_site: Some(span),
-            format: source_map::CompilerDesugaring(reason),
             allow_internal_unstable,
-            allow_internal_unsafe: false,
-            local_inner_macros: false,
-            edition: edition::Edition::from_session(),
+            ..ExpnInfo::default(source_map::CompilerDesugaring(reason), span, self.sess.edition())
         });
         span.with_ctxt(SyntaxContext::empty().apply_mark(mark))
     }
@@ -1156,7 +1157,7 @@ impl<'a> LoweringContext<'a> {
         let unstable_span = self.mark_span_with_reason(
             CompilerDesugaringKind::Async,
             span,
-            Some(vec![sym::gen_future].into()),
+            self.allow_gen_future.clone(),
         );
         let gen_future = self.expr_std_path(
             unstable_span, &[sym::future, sym::from_generator], None, ThinVec::new());
@@ -4382,7 +4383,7 @@ impl<'a> LoweringContext<'a> {
                     let unstable_span = this.mark_span_with_reason(
                         CompilerDesugaringKind::TryBlock,
                         body.span,
-                        Some(vec![sym::try_trait].into()),
+                        this.allow_try_trait.clone(),
                     );
                     let mut block = this.lower_block(body, true).into_inner();
                     let tail = block.expr.take().map_or_else(
@@ -4968,13 +4969,13 @@ impl<'a> LoweringContext<'a> {
                 let unstable_span = self.mark_span_with_reason(
                     CompilerDesugaringKind::QuestionMark,
                     e.span,
-                    Some(vec![sym::try_trait].into()),
+                    self.allow_try_trait.clone(),
                 );
                 let try_span = self.sess.source_map().end_point(e.span);
                 let try_span = self.mark_span_with_reason(
                     CompilerDesugaringKind::QuestionMark,
                     try_span,
-                    Some(vec![sym::try_trait].into()),
+                    self.allow_try_trait.clone(),
                 );
 
                 // `Try::into_result(<expr>)`
@@ -5776,7 +5777,7 @@ impl<'a> LoweringContext<'a> {
         let gen_future_span = self.mark_span_with_reason(
             CompilerDesugaringKind::Await,
             await_span,
-            Some(vec![sym::gen_future].into()),
+            self.allow_gen_future.clone(),
         );
 
         // let mut pinned = <expr>;

src/librustc/ich/impls_syntax.rs

@@ -391,10 +391,17 @@ impl_stable_hash_for!(enum ::syntax::ast::MetaItemKind {
     NameValue(lit)
 });
 
+impl_stable_hash_for!(enum ::syntax_pos::hygiene::Transparency {
+    Transparent,
+    SemiTransparent,
+    Opaque,
+});
+
 impl_stable_hash_for!(struct ::syntax_pos::hygiene::ExpnInfo {
     call_site,
-    def_site,
     format,
+    def_site,
+    default_transparency,
     allow_internal_unstable,
     allow_internal_unsafe,
     local_inner_macros,

src/librustc_allocator/expand.rs

@@ -19,7 +19,7 @@ use syntax::{
     mut_visit::{self, MutVisitor},
     parse::ParseSess,
     ptr::P,
-    symbol::{kw, sym, Symbol}
+    symbol::{kw, sym}
 };
 use syntax_pos::Span;
 
@@ -58,11 +58,10 @@ impl MutVisitor for ExpandAllocatorDirectives<'_> {
     fn flat_map_item(&mut self, item: P<Item>) -> SmallVec<[P<Item>; 1]> {
         debug!("in submodule {}", self.in_submod);
 
-        let name = if attr::contains_name(&item.attrs, sym::global_allocator) {
-            "global_allocator"
-        } else {
+        if !attr::contains_name(&item.attrs, sym::global_allocator) {
             return mut_visit::noop_flat_map_item(item, self);
-        };
+        }
+
         match item.node {
             ItemKind::Static(..) => {}
             _ => {
@@ -87,15 +86,9 @@ impl MutVisitor for ExpandAllocatorDirectives<'_> {
 
         // Create a fresh Mark for the new macro expansion we are about to do
         let mark = Mark::fresh(Mark::root());
-        mark.set_expn_info(ExpnInfo {
-            call_site: item.span, // use the call site of the static
-            def_site: None,
-            format: MacroAttribute(Symbol::intern(name)),
-            allow_internal_unstable: Some(vec![sym::rustc_attrs].into()),
-            allow_internal_unsafe: false,
-            local_inner_macros: false,
-            edition: self.sess.edition,
-        });
+        mark.set_expn_info(ExpnInfo::with_unstable(
+            MacroAttribute(sym::global_allocator), item.span, self.sess.edition, &[sym::rustc_attrs]
+        ));
 
         // Tie the span to the macro expansion info we just created
         let span = item.span.with_ctxt(SyntaxContext::empty().apply_mark(mark));

src/librustc_metadata/creader.rs

@@ -26,7 +26,7 @@ use std::{cmp, fs};
 
 use syntax::ast;
 use syntax::attr;
-use syntax::ext::base::SyntaxExtension;
+use syntax::ext::base::{SyntaxExtension, SyntaxExtensionKind};
 use syntax::symbol::{Symbol, sym};
 use syntax::visit;
 use syntax::{span_err, span_fatal};
@@ -611,33 +611,31 @@ impl<'a> CrateLoader<'a> {
         };
 
         let extensions = decls.iter().map(|&decl| {
-            match decl {
+            let (name, kind, helper_attrs) = match decl {
                 ProcMacro::CustomDerive { trait_name, attributes, client } => {
-                    let attrs = attributes.iter().cloned().map(Symbol::intern).collect::<Vec<_>>();
-                    (trait_name, SyntaxExtension::Derive(
-                        Box::new(ProcMacroDerive {
-                            client,
-                            attrs: attrs.clone(),
-                        }),
-                        attrs,
-                        root.edition,
-                    ))
+                    let helper_attrs =
+                        attributes.iter().cloned().map(Symbol::intern).collect::<Vec<_>>();
+                    (
+                        trait_name,
+                        SyntaxExtensionKind::Derive(Box::new(ProcMacroDerive {
+                            client, attrs: helper_attrs.clone()
+                        })),
+                        helper_attrs,
+                    )
                 }
-                ProcMacro::Attr { name, client } => {
-                    (name, SyntaxExtension::Attr(
-                        Box::new(AttrProcMacro { client }),
-                        root.edition,
-                    ))
-                }
-                ProcMacro::Bang { name, client } => {
-                    (name, SyntaxExtension::Bang {
-                        expander: Box::new(BangProcMacro { client }),
-                        allow_internal_unstable: None,
-                        edition: root.edition,
-                    })
-                }
-            }
-        }).map(|(name, ext)| (Symbol::intern(name), Lrc::new(ext))).collect();
+                ProcMacro::Attr { name, client } => (
+                    name, SyntaxExtensionKind::Attr(Box::new(AttrProcMacro { client })), Vec::new()
+                ),
+                ProcMacro::Bang { name, client } => (
+                    name, SyntaxExtensionKind::Bang(Box::new(BangProcMacro { client })), Vec::new()
+                )
+            };
+
+            (Symbol::intern(name), Lrc::new(SyntaxExtension {
+                helper_attrs,
+                ..SyntaxExtension::default(kind, root.edition)
+            }))
+        }).collect();
 
         // Intentionally leak the dynamic library. We can't ever unload it
         // since the library can make things that will live arbitrarily long.

src/librustc_metadata/cstore_impl.rs

@@ -30,9 +30,11 @@ use syntax::ast;
 use syntax::attr;
 use syntax::source_map;
 use syntax::edition::Edition;
+use syntax::ext::base::{SyntaxExtension, SyntaxExtensionKind};
 use syntax::parse::source_file_to_stream;
 use syntax::parse::parser::emit_unclosed_delims;
 use syntax::symbol::{Symbol, sym};
+use syntax_ext::proc_macro_impl::BangProcMacro;
 use syntax_pos::{Span, NO_EXPANSION, FileName};
 use rustc_data_structures::bit_set::BitSet;
 
@@ -427,14 +429,11 @@ impl cstore::CStore {
         if let Some(ref proc_macros) = data.proc_macros {
             return LoadedMacro::ProcMacro(proc_macros[id.index.to_proc_macro_index()].1.clone());
         } else if data.name == sym::proc_macro && data.item_name(id.index) == sym::quote {
-            use syntax::ext::base::SyntaxExtension;
-            use syntax_ext::proc_macro_impl::BangProcMacro;
-
             let client = proc_macro::bridge::client::Client::expand1(proc_macro::quote);
-            let ext = SyntaxExtension::Bang {
-                expander: Box::new(BangProcMacro { client }),
-                allow_internal_unstable: Some(vec![sym::proc_macro_def_site].into()),
-                edition: data.root.edition,
+            let kind = SyntaxExtensionKind::Bang(Box::new(BangProcMacro { client }));
+            let ext = SyntaxExtension {
+                allow_internal_unstable: Some([sym::proc_macro_def_site][..].into()),
+                ..SyntaxExtension::default(kind, data.root.edition)
             };
             return LoadedMacro::ProcMacro(Lrc::new(ext));
         }

src/librustc_metadata/decoder.rs

@@ -511,8 +511,9 @@ impl<'a, 'tcx> CrateMetadata {
         if !self.is_proc_macro(index) {
             self.entry(index).kind.def_kind()
         } else {
-            let kind = self.proc_macros.as_ref().unwrap()[index.to_proc_macro_index()].1.kind();
-            Some(DefKind::Macro(kind))
+            Some(DefKind::Macro(
+                self.proc_macros.as_ref().unwrap()[index.to_proc_macro_index()].1.macro_kind()
+            ))
         }
     }
 
@@ -739,7 +740,7 @@ impl<'a, 'tcx> CrateMetadata {
             if id == CRATE_DEF_INDEX {
                 for (id, &(name, ref ext)) in proc_macros.iter().enumerate() {
                     let res = Res::Def(
-                        DefKind::Macro(ext.kind()),
+                        DefKind::Macro(ext.macro_kind()),
                         self.local_def_id(DefIndex::from_proc_macro_index(id)),
                     );
                     let ident = Ident::with_empty_ctxt(name);

src/librustc_plugin/registry.rs

@@ -4,9 +4,8 @@ use rustc::lint::{EarlyLintPassObject, LateLintPassObject, LintId, Lint};
 use rustc::session::Session;
 use rustc::util::nodemap::FxHashMap;
 
-use syntax::ext::base::{SyntaxExtension, NamedSyntaxExtension};
+use syntax::ext::base::{SyntaxExtension, SyntaxExtensionKind, NamedSyntaxExtension};
 use syntax::ext::base::MacroExpanderFn;
-use syntax::ext::hygiene::Transparency;
 use syntax::symbol::{Symbol, sym};
 use syntax::ast;
 use syntax::feature_gate::AttributeType;
@@ -89,28 +88,21 @@ impl<'a> Registry<'a> {
         if name == sym::macro_rules {
             panic!("user-defined macros may not be named `macro_rules`");
         }
-        if let SyntaxExtension::LegacyBang { def_info: ref mut def_info @ None, .. } = extension {
-            *def_info = Some((ast::CRATE_NODE_ID, self.krate_span));
+        if extension.def_info.is_none() {
+            extension.def_info = Some((ast::CRATE_NODE_ID, self.krate_span));
         }
         self.syntax_exts.push((name, extension));
     }
 
     /// Register a macro of the usual kind.
     ///
     /// This is a convenience wrapper for `register_syntax_extension`.
-    /// It builds for you a `SyntaxExtension::LegacyBang` that calls `expander`,
+    /// It builds for you a `SyntaxExtensionKind::LegacyBang` that calls `expander`,
     /// and also takes care of interning the macro's name.
     pub fn register_macro(&mut self, name: &str, expander: MacroExpanderFn) {
-        self.register_syntax_extension(Symbol::intern(name), SyntaxExtension::LegacyBang {
-            expander: Box::new(expander),
-            def_info: None,
-            transparency: Transparency::SemiTransparent,
-            allow_internal_unstable: None,
-            allow_internal_unsafe: false,
-            local_inner_macros: false,
-            unstable_feature: None,
-            edition: self.sess.edition(),
-        });
+        let kind = SyntaxExtensionKind::LegacyBang(Box::new(expander));
+        let ext = SyntaxExtension::default(kind, self.sess.edition());
+        self.register_syntax_extension(Symbol::intern(name), ext);
     }
 
     /// Register a compiler lint pass.

src/librustc_resolve/build_reduced_graph.rs

@@ -772,9 +772,8 @@ impl<'a> Resolver<'a> {
     pub fn get_macro(&mut self, res: Res) -> Lrc<SyntaxExtension> {
         let def_id = match res {
             Res::Def(DefKind::Macro(..), def_id) => def_id,
-            Res::NonMacroAttr(attr_kind) => return Lrc::new(SyntaxExtension::NonMacroAttr {
-                mark_used: attr_kind == NonMacroAttrKind::Tool,
-            }),
+            Res::NonMacroAttr(attr_kind) =>
+                return self.non_macro_attr(attr_kind == NonMacroAttrKind::Tool),
             _ => panic!("expected `DefKind::Macro` or `Res::NonMacroAttr`"),
         };
         if let Some(ext) = self.macro_map.get(&def_id) {

src/librustc_resolve/lib.rs

@@ -41,7 +41,7 @@ use rustc_metadata::cstore::CStore;
 use syntax::source_map::SourceMap;
 use syntax::ext::hygiene::{Mark, Transparency, SyntaxContext};
 use syntax::ast::{self, Name, NodeId, Ident, FloatTy, IntTy, UintTy};
-use syntax::ext::base::SyntaxExtension;
+use syntax::ext::base::{SyntaxExtension, SyntaxExtensionKind};
 use syntax::ext::base::Determinacy::{self, Determined, Undetermined};
 use syntax::ext::base::MacroKind;
 use syntax::symbol::{Symbol, kw, sym};
@@ -1668,6 +1668,7 @@ pub struct Resolver<'a> {
     macro_use_prelude: FxHashMap<Name, &'a NameBinding<'a>>,
     pub all_macros: FxHashMap<Name, Res>,
     macro_map: FxHashMap<DefId, Lrc<SyntaxExtension>>,
+    non_macro_attrs: [Lrc<SyntaxExtension>; 2],
     macro_defs: FxHashMap<Mark, DefId>,
     local_macro_def_scopes: FxHashMap<NodeId, Module<'a>>,
 
@@ -1941,6 +1942,10 @@ impl<'a> Resolver<'a> {
         let mut macro_defs = FxHashMap::default();
         macro_defs.insert(Mark::root(), root_def_id);
 
+        let non_macro_attr = |mark_used| Lrc::new(SyntaxExtension::default(
+            SyntaxExtensionKind::NonMacroAttr { mark_used }, session.edition()
+        ));
+
         Resolver {
             session,
 
@@ -2014,6 +2019,7 @@ impl<'a> Resolver<'a> {
             macro_use_prelude: FxHashMap::default(),
             all_macros: FxHashMap::default(),
             macro_map: FxHashMap::default(),
+            non_macro_attrs: [non_macro_attr(false), non_macro_attr(true)],
             invocations,
             macro_defs,
             local_macro_def_scopes: FxHashMap::default(),
@@ -2030,6 +2036,10 @@ impl<'a> Resolver<'a> {
         Default::default()
     }
 
+    fn non_macro_attr(&self, mark_used: bool) -> Lrc<SyntaxExtension> {
+        self.non_macro_attrs[mark_used as usize].clone()
+    }
+
     /// Runs the function on each namespace.
     fn per_ns<F: FnMut(&mut Self, Namespace)>(&mut self, mut f: F) {
         f(self, TypeNS);