Auto merge of #49154 - petrochenkov:spident, r=eddyb

AST: Give spans to all identifiers

Change representation of `ast::Ident` from `{ name: Symbol, ctxt: SyntaxContext }` to `{ name: Symbol, span: Span }`.
Syntax contexts still can be extracted from spans (`span.ctxt()`).

Why this should not require more memory:
- `Span` is `u32` just like `SyntaxContext`.
- Despite keeping more spans in AST we don't actually *create* more spans, so the number of "outlined" spans kept in span interner shouldn't become larger.

Why this may be slightly slower:
- When we need to extract ctxt from an identifier instead of just field read we need to do bit field extraction possibly followed by and access by index into span interner's vector. Both operations should be fast (unless the span interner is under some synchronization) and we already do ctxt extraction from spans all the time during macro expansion, so the difference should be lost in noise.

cc #48842 (comment)

Author: bors

src/libproc_macro/lib.rs

@@ -1097,15 +1097,17 @@ impl TokenTree {
                 }).into();
             },
             self::TokenTree::Term(tt) => {
-                let ident = ast::Ident { name: tt.sym, ctxt: tt.span.0.ctxt() };
+                let ident = ast::Ident::new(tt.sym, tt.span.0);
                 let sym_str = tt.sym.as_str();
-                let token =
-                    if sym_str.starts_with("'") { Lifetime(ident) }
-                    else if sym_str.starts_with("r#") {
-                        let name = Symbol::intern(&sym_str[2..]);
-                        let ident = ast::Ident { name, ctxt: tt.span.0.ctxt() };
-                        Ident(ident, true)
-                    } else { Ident(ident, false) };
+                let token = if sym_str.starts_with("'") {
+                    Lifetime(ident)
+                } else if sym_str.starts_with("r#") {
+                    let name = Symbol::intern(&sym_str[2..]);
+                    let ident = ast::Ident::new(name, ident.span);
+                    Ident(ident, true)
+                } else {
+                    Ident(ident, false)
+                };
                 return TokenTree::Token(tt.span.0, token).into();
             }
             self::TokenTree::Literal(self::Literal {

src/librustc/hir/lowering.rs

@@ -909,7 +909,7 @@ impl<'a> LoweringContext<'a> {
 
     fn lower_ident(&mut self, ident: Ident) -> Name {
         let ident = ident.modern();
-        if ident.ctxt == SyntaxContext::empty() {
+        if ident.span.ctxt() == SyntaxContext::empty() {
             return ident.name;
         }
         *self.name_map
@@ -920,7 +920,7 @@ impl<'a> LoweringContext<'a> {
     fn lower_label(&mut self, label: Option<Label>) -> Option<hir::Label> {
         label.map(|label| hir::Label {
             name: label.ident.name,
-            span: label.span,
+            span: label.ident.span,
         })
     }
 
@@ -1358,7 +1358,7 @@ impl<'a> LoweringContext<'a> {
     fn lower_variant(&mut self, v: &Variant) -> hir::Variant {
         Spanned {
             node: hir::Variant_ {
-                name: v.node.name.name,
+                name: v.node.ident.name,
                 attrs: self.lower_attrs(&v.node.attrs),
                 data: self.lower_variant_data(&v.node.data),
                 disr_expr: v.node
@@ -1607,7 +1607,7 @@ impl<'a> LoweringContext<'a> {
         }
 
         hir::PathSegment::new(
-            self.lower_ident(segment.identifier),
+            self.lower_ident(segment.ident),
             parameters,
             infer_types,
         )
@@ -1720,7 +1720,7 @@ impl<'a> LoweringContext<'a> {
         decl.inputs
             .iter()
             .map(|arg| match arg.pat.node {
-                PatKind::Ident(_, ident, None) => respan(ident.span, ident.node.name),
+                PatKind::Ident(_, ident, None) => respan(ident.span, ident.name),
                 _ => respan(arg.pat.span, keywords::Invalid.name()),
             })
             .collect()
@@ -1810,7 +1810,7 @@ impl<'a> LoweringContext<'a> {
             default: tp.default
                 .as_ref()
                 .map(|x| self.lower_ty(x, ImplTraitContext::Disallowed)),
-            span: tp.span,
+            span: tp.ident.span,
             pure_wrt_drop: attr::contains_name(&tp.attrs, "may_dangle"),
             synthetic: tp.attrs
                 .iter()
@@ -1822,21 +1822,22 @@ impl<'a> LoweringContext<'a> {
     }
 
     fn lower_lifetime(&mut self, l: &Lifetime) -> hir::Lifetime {
+        let span = l.ident.span;
         match self.lower_ident(l.ident) {
-            x if x == "'static" => self.new_named_lifetime(l.id, l.span, hir::LifetimeName::Static),
+            x if x == "'static" => self.new_named_lifetime(l.id, span, hir::LifetimeName::Static),
             x if x == "'_" => match self.anonymous_lifetime_mode {
                 AnonymousLifetimeMode::CreateParameter => {
-                    let fresh_name = self.collect_fresh_in_band_lifetime(l.span);
-                    self.new_named_lifetime(l.id, l.span, fresh_name)
+                    let fresh_name = self.collect_fresh_in_band_lifetime(span);
+                    self.new_named_lifetime(l.id, span, fresh_name)
                 }
 
                 AnonymousLifetimeMode::PassThrough => {
-                    self.new_named_lifetime(l.id, l.span, hir::LifetimeName::Underscore)
+                    self.new_named_lifetime(l.id, span, hir::LifetimeName::Underscore)
                 }
             },
             name => {
-                self.maybe_collect_in_band_lifetime(l.span, name);
-                self.new_named_lifetime(l.id, l.span, hir::LifetimeName::Name(name))
+                self.maybe_collect_in_band_lifetime(span, name);
+                self.new_named_lifetime(l.id, span, hir::LifetimeName::Name(name))
             }
         }
     }
@@ -2089,10 +2090,7 @@ impl<'a> LoweringContext<'a> {
             name: self.lower_ident(match f.ident {
                 Some(ident) => ident,
                 // FIXME(jseyfried) positional field hygiene
-                None => Ident {
-                    name: Symbol::intern(&index.to_string()),
-                    ctxt: f.span.ctxt(),
-                },
+                None => Ident::new(Symbol::intern(&index.to_string()), f.span),
             }),
             vis: self.lower_visibility(&f.vis, None),
             ty: self.lower_ty(&f.ty, ImplTraitContext::Disallowed),
@@ -2102,7 +2100,7 @@ impl<'a> LoweringContext<'a> {
 
     fn lower_field(&mut self, f: &Field) -> hir::Field {
         hir::Field {
-            name: respan(f.ident.span, self.lower_ident(f.ident.node)),
+            name: respan(f.ident.span, self.lower_ident(f.ident)),
             expr: P(self.lower_expr(&f.expr)),
             span: f.span,
             is_shorthand: f.is_shorthand,
@@ -2359,11 +2357,11 @@ impl<'a> LoweringContext<'a> {
 
                 // Correctly resolve `self` imports
                 if path.segments.len() > 1
-                    && path.segments.last().unwrap().identifier.name == keywords::SelfValue.name()
+                    && path.segments.last().unwrap().ident.name == keywords::SelfValue.name()
                 {
                     let _ = path.segments.pop();
                     if rename.is_none() {
-                        *name = path.segments.last().unwrap().identifier.name;
+                        *name = path.segments.last().unwrap().ident.name;
                     }
                 }
 
@@ -2804,7 +2802,7 @@ impl<'a> LoweringContext<'a> {
     fn lower_pat(&mut self, p: &Pat) -> P<hir::Pat> {
         let node = match p.node {
             PatKind::Wild => hir::PatKind::Wild,
-            PatKind::Ident(ref binding_mode, pth1, ref sub) => {
+            PatKind::Ident(ref binding_mode, ident, ref sub) => {
                 match self.resolver.get_resolution(p.id).map(|d| d.base_def()) {
                     // `None` can occur in body-less function signatures
                     def @ None | def @ Some(Def::Local(_)) => {
@@ -2815,16 +2813,16 @@ impl<'a> LoweringContext<'a> {
                         hir::PatKind::Binding(
                             self.lower_binding_mode(binding_mode),
                             canonical_id,
-                            respan(pth1.span, pth1.node.name),
+                            respan(ident.span, ident.name),
                             sub.as_ref().map(|x| self.lower_pat(x)),
                         )
                     }
                     Some(def) => hir::PatKind::Path(hir::QPath::Resolved(
                         None,
                         P(hir::Path {
-                            span: pth1.span,
+                            span: ident.span,
                             def,
-                            segments: hir_vec![hir::PathSegment::from_name(pth1.node.name)],
+                            segments: hir_vec![hir::PathSegment::from_name(ident.name)],
                         }),
                     )),
                 }
@@ -2939,7 +2937,7 @@ impl<'a> LoweringContext<'a> {
                     ImplTraitContext::Disallowed,
                 );
                 let args = args.iter().map(|x| self.lower_expr(x)).collect();
-                hir::ExprMethodCall(hir_seg, seg.span, args)
+                hir::ExprMethodCall(hir_seg, seg.ident.span, args)
             }
             ExprKind::Binary(binop, ref lhs, ref rhs) => {
                 let binop = self.lower_binop(binop);
@@ -3074,7 +3072,7 @@ impl<'a> LoweringContext<'a> {
             ),
             ExprKind::Field(ref el, ident) => hir::ExprField(
                 P(self.lower_expr(el)),
-                respan(ident.span, self.lower_ident(ident.node)),
+                respan(ident.span, self.lower_ident(ident)),
             ),
             ExprKind::TupField(ref el, ident) => hir::ExprTupField(P(self.lower_expr(el)), ident),
             ExprKind::Index(ref el, ref er) => {
@@ -3505,12 +3503,10 @@ impl<'a> LoweringContext<'a> {
                 let attr = {
                     // allow(unreachable_code)
                     let allow = {
-                        let allow_ident = self.str_to_ident("allow");
-                        let uc_ident = self.str_to_ident("unreachable_code");
-                        let uc_meta_item = attr::mk_spanned_word_item(e.span, uc_ident);
-                        let uc_nested = NestedMetaItemKind::MetaItem(uc_meta_item);
-                        let uc_spanned = respan(e.span, uc_nested);
-                        attr::mk_spanned_list_item(e.span, allow_ident, vec![uc_spanned])
+                        let allow_ident = Ident::from_str("allow").with_span_pos(e.span);
+                        let uc_ident = Ident::from_str("unreachable_code").with_span_pos(e.span);
+                        let uc_nested = attr::mk_nested_word_item(uc_ident);
+                        attr::mk_list_item(e.span, allow_ident, vec![uc_nested])
                     };
                     attr::mk_spanned_attr_outer(e.span, attr::mk_attr_id(), allow)
                 };

src/librustc/hir/map/def_collector.rs

@@ -132,7 +132,7 @@ impl<'a> visit::Visitor<'a> for DefCollector<'a> {
                     for v in &enum_definition.variants {
                         let variant_def_index =
                             this.create_def(v.node.data.id(),
-                                            DefPathData::EnumVariant(v.node.name.name.as_str()),
+                                            DefPathData::EnumVariant(v.node.ident.name.as_str()),
                                             REGULAR_SPACE,
                                             v.span);
                         this.with_parent(variant_def_index, |this| {
@@ -202,15 +202,15 @@ impl<'a> visit::Visitor<'a> for DefCollector<'a> {
                     lifetime_def.lifetime.id,
                     DefPathData::LifetimeDef(lifetime_def.lifetime.ident.name.as_str()),
                     REGULAR_SPACE,
-                    lifetime_def.lifetime.span
+                    lifetime_def.lifetime.ident.span
                 );
             }
             GenericParam::Type(ref ty_param) => {
                 self.create_def(
                     ty_param.id,
                     DefPathData::TypeParam(ty_param.ident.name.as_str()),
                     REGULAR_SPACE,
-                    ty_param.span
+                    ty_param.ident.span
                 );
             }
         }

src/librustc/ich/impls_hir.rs

@@ -654,11 +654,12 @@ impl<'a> HashStable<StableHashingContext<'a>> for ast::Ident {
                                           hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         let ast::Ident {
-            ref name,
-            ctxt: _ // Ignore this
+            name,
+            span,
         } = *self;
 
         name.hash_stable(hcx, hasher);
+        span.hash_stable(hcx, hasher);
     }
 }
 

src/librustc/ich/impls_syntax.rs

@@ -162,7 +162,7 @@ impl_stable_hash_for!(enum ::syntax::ast::FloatTy { F32, F64 });
 impl_stable_hash_for!(enum ::syntax::ast::Unsafety { Unsafe, Normal });
 impl_stable_hash_for!(enum ::syntax::ast::Constness { Const, NotConst });
 impl_stable_hash_for!(enum ::syntax::ast::Defaultness { Default, Final });
-impl_stable_hash_for!(struct ::syntax::ast::Lifetime { id, span, ident });
+impl_stable_hash_for!(struct ::syntax::ast::Lifetime { id, ident });
 impl_stable_hash_for!(enum ::syntax::ast::StrStyle { Cooked, Raw(pounds) });
 impl_stable_hash_for!(enum ::syntax::ast::AttrStyle { Outer, Inner });
 
@@ -211,7 +211,7 @@ impl<'a> HashStable<StableHashingContext<'a>> for ast::Attribute {
         style.hash_stable(hcx, hasher);
         path.segments.len().hash_stable(hcx, hasher);
         for segment in &path.segments {
-            segment.identifier.name.hash_stable(hcx, hasher);
+            segment.ident.name.hash_stable(hcx, hasher);
         }
         for tt in tokens.trees() {
             tt.hash_stable(hcx, hasher);
@@ -341,7 +341,7 @@ impl_stable_hash_for!(enum ::syntax::ast::NestedMetaItemKind {
 });
 
 impl_stable_hash_for!(struct ::syntax::ast::MetaItem {
-    name,
+    ident,
     node,
     span
 });

src/librustc/lint/context.rs

@@ -952,8 +952,8 @@ impl<'a> ast_visit::Visitor<'a> for EarlyContext<'a> {
         ast_visit::walk_ty(self, t);
     }
 
-    fn visit_ident(&mut self, sp: Span, id: ast::Ident) {
-        run_lints!(self, check_ident, early_passes, sp, id);
+    fn visit_ident(&mut self, ident: ast::Ident) {
+        run_lints!(self, check_ident, early_passes, ident);
     }
 
     fn visit_mod(&mut self, m: &'a ast::Mod, s: Span, _a: &[ast::Attribute], n: ast::NodeId) {

src/librustc/lint/levels.rs

@@ -221,7 +221,7 @@ impl<'a> LintLevelsBuilder<'a> {
                         continue
                     }
                 };
-                let name = word.name();
+                let name = word.ident.name;
                 match store.check_lint_name(&name.as_str()) {
                     CheckLintNameResult::Ok(ids) => {
                         let src = LintSource::Node(name, li.span);

src/librustc/lint/mod.rs

@@ -236,7 +236,7 @@ pub trait LateLintPass<'a, 'tcx>: LintPass {
 }
 
 pub trait EarlyLintPass: LintPass {
-    fn check_ident(&mut self, _: &EarlyContext, _: Span, _: ast::Ident) { }
+    fn check_ident(&mut self, _: &EarlyContext, _: ast::Ident) { }
     fn check_crate(&mut self, _: &EarlyContext, _: &ast::Crate) { }
     fn check_crate_post(&mut self, _: &EarlyContext, _: &ast::Crate) { }
     fn check_mod(&mut self, _: &EarlyContext, _: &ast::Mod, _: Span, _: ast::NodeId) { }

src/librustc/session/config.rs

@@ -1683,12 +1683,12 @@ pub fn parse_cfgspecs(cfgspecs: Vec<String>) -> ast::CrateConfig {
             } else if meta_item.is_meta_item_list() {
                 let msg = format!(
                     "invalid predicate in --cfg command line argument: `{}`",
-                    meta_item.name()
+                    meta_item.ident
                 );
                 early_error(ErrorOutputType::default(), &msg)
             }
 
-            (meta_item.name(), meta_item.value_str())
+            (meta_item.ident.name, meta_item.value_str())
         })
         .collect::<ast::CrateConfig>()
 }

src/librustc/traits/on_unimplemented.rs

@@ -190,7 +190,7 @@ impl<'a, 'gcx, 'tcx> OnUnimplementedDirective {
         for command in self.subcommands.iter().chain(Some(self)).rev() {
             if let Some(ref condition) = command.condition {
                 if !attr::eval_condition(condition, &tcx.sess.parse_sess, &mut |c| {
-                    options.contains(&(c.name().as_str().to_string(),
+                    options.contains(&(c.ident.name.as_str().to_string(),
                                       match c.value_str().map(|s| s.as_str().to_string()) {
                                           Some(s) => Some(s),
                                           None => None