Rollup merge of #63535 - petrochenkov:expndata, r=matthewjasper

Continue refactoring resolve and hygiene

The general goal is addressing FIXMEs from the previous PRs.

Merging similar data structures (+ prerequisites for such merging), accounting for the fact that all `ExpnId`s have associated data in `HygieneData` now (less `Option`s).

Also, some renaming.
This should be the last renaming session in this area, I think.

r? @matthewjasper

18 files changed, 81 insertions, 109 deletions

diff --git a/src/libsyntax/attr/mod.rs b/src/libsyntax/attr/mod.rs
index 85c661d320a..bcf03b5237a 100644
--- a/src/libsyntax/attr/mod.rs
+++ b/src/libsyntax/attr/mod.rs
@@ -327,7 +327,7 @@ impl Attribute {
         if self.is_sugared_doc {
             let comment = self.value_str().unwrap();
             let meta = mk_name_value_item_str(
-                Ident::with_empty_ctxt(sym::doc),
+                Ident::with_dummy_span(sym::doc),
                 Symbol::intern(&strip_doc_comment_decoration(&comment.as_str())),
                 DUMMY_SP,
             );
@@ -412,7 +412,7 @@ pub fn mk_sugared_doc_attr(text: Symbol, span: Span) -> Attribute {
     Attribute {
         id: mk_attr_id(),
         style,
-        path: Path::from_ident(Ident::with_empty_ctxt(sym::doc).with_span_pos(span)),
+        path: Path::from_ident(Ident::with_dummy_span(sym::doc).with_span_pos(span)),
         tokens: MetaItemKind::NameValue(lit).tokens(span),
         is_sugared_doc: true,
         span,
diff --git a/src/libsyntax/diagnostics/plugin.rs b/src/libsyntax/diagnostics/plugin.rs
index 80591ad304d..9618b5acfb0 100644
--- a/src/libsyntax/diagnostics/plugin.rs
+++ b/src/libsyntax/diagnostics/plugin.rs
@@ -172,7 +172,7 @@ pub fn expand_build_diagnostic_array<'cx>(ecx: &'cx mut ExtCtxt<'_>,
             (descriptions.len(), ecx.expr_vec(span, descriptions))
         });
 
-    let static_ = ecx.lifetime(span, Ident::with_empty_ctxt(kw::StaticLifetime));
+    let static_ = ecx.lifetime(span, Ident::with_dummy_span(kw::StaticLifetime));
     let ty_str = ecx.ty_rptr(
         span,
         ecx.ty_ident(span, ecx.ident_of("str")),
diff --git a/src/libsyntax/ext/base.rs b/src/libsyntax/ext/base.rs
index edeca046c7b..fb1bf4d7160 100644
--- a/src/libsyntax/ext/base.rs
+++ b/src/libsyntax/ext/base.rs
@@ -15,7 +15,7 @@ use crate::tokenstream::{self, TokenStream, TokenTree};
 use errors::{DiagnosticBuilder, DiagnosticId};
 use smallvec::{smallvec, SmallVec};
 use syntax_pos::{FileName, Span, MultiSpan, DUMMY_SP};
-use syntax_pos::hygiene::{ExpnInfo, ExpnKind};
+use syntax_pos::hygiene::{ExpnData, ExpnKind};
 
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::sync::{self, Lrc};
@@ -640,10 +640,11 @@ impl SyntaxExtension {
         SyntaxExtension::default(SyntaxExtensionKind::NonMacroAttr { mark_used }, edition)
     }
 
-    pub fn expn_info(&self, call_site: Span, descr: Symbol) -> ExpnInfo {
-        ExpnInfo {
-            call_site,
+    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,
             default_transparency: self.default_transparency,
             allow_internal_unstable: self.allow_internal_unstable.clone(),
@@ -707,7 +708,7 @@ pub struct ExpansionData {
 
 /// 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_info` of their expansion context stored into their span.
+/// -> 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>,
@@ -756,13 +757,10 @@ impl<'a> ExtCtxt<'a> {
     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 {
-        match self.current_expansion.id.expn_info() {
-            Some(expn_info) => expn_info.call_site,
-            None => DUMMY_SP,
-        }
+        self.current_expansion.id.expn_data().call_site
     }
     pub fn backtrace(&self) -> SyntaxContext {
-        SyntaxContext::empty().apply_mark(self.current_expansion.id)
+        SyntaxContext::root().apply_mark(self.current_expansion.id)
     }
 
     /// Returns span for the macro which originally caused the current expansion to happen.
@@ -772,17 +770,13 @@ impl<'a> ExtCtxt<'a> {
         let mut ctxt = self.backtrace();
         let mut last_macro = None;
         loop {
-            if ctxt.outer_expn_info().map_or(None, |info| {
-                if info.kind.descr() == sym::include {
-                    // Stop going up the backtrace once include! is encountered
-                    return None;
-                }
-                ctxt = info.call_site.ctxt();
-                last_macro = Some(info.call_site);
-                Some(())
-            }).is_none() {
-                break
+            let expn_data = ctxt.outer_expn_data();
+            // Stop going up the backtrace once include! is encountered
+            if expn_data.is_root() || expn_data.kind.descr() == sym::include {
+                break;
             }
+            ctxt = expn_data.call_site.ctxt();
+            last_macro = Some(expn_data.call_site);
         }
         last_macro
     }
@@ -872,7 +866,7 @@ impl<'a> ExtCtxt<'a> {
     pub fn std_path(&self, components: &[Symbol]) -> Vec<ast::Ident> {
         let def_site = DUMMY_SP.apply_mark(self.current_expansion.id);
         iter::once(Ident::new(kw::DollarCrate, def_site))
-            .chain(components.iter().map(|&s| Ident::with_empty_ctxt(s)))
+            .chain(components.iter().map(|&s| Ident::with_dummy_span(s)))
             .collect()
     }
     pub fn name_of(&self, st: &str) -> ast::Name {
diff --git a/src/libsyntax/ext/build.rs b/src/libsyntax/ext/build.rs
index 38f46ee207c..e2ac4d573a1 100644
--- a/src/libsyntax/ext/build.rs
+++ b/src/libsyntax/ext/build.rs
@@ -340,7 +340,7 @@ impl<'a> ExtCtxt<'a> {
         self.expr_path(self.path_ident(span, id))
     }
     pub fn expr_self(&self, span: Span) -> P<ast::Expr> {
-        self.expr_ident(span, Ident::with_empty_ctxt(kw::SelfLower))
+        self.expr_ident(span, Ident::with_dummy_span(kw::SelfLower))
     }
 
     pub fn expr_binary(&self, sp: Span, op: ast::BinOpKind,
diff --git a/src/libsyntax/ext/expand.rs b/src/libsyntax/ext/expand.rs
index 97983944931..e7deadbc9a0 100644
--- a/src/libsyntax/ext/expand.rs
+++ b/src/libsyntax/ext/expand.rs
@@ -5,7 +5,7 @@ use crate::source_map::respan;
 use crate::config::StripUnconfigured;
 use crate::ext::base::*;
 use crate::ext::proc_macro::collect_derives;
-use crate::ext::hygiene::{ExpnId, SyntaxContext, ExpnInfo, ExpnKind};
+use crate::ext::hygiene::{ExpnId, SyntaxContext, ExpnData, ExpnKind};
 use crate::ext::tt::macro_rules::annotate_err_with_kind;
 use crate::ext::placeholders::{placeholder, PlaceholderExpander};
 use crate::feature_gate::{self, Features, GateIssue, is_builtin_attr, emit_feature_err};
@@ -353,7 +353,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                 derives.reserve(traits.len());
                 invocations.reserve(traits.len());
                 for path in traits {
-                    let expn_id = ExpnId::fresh(self.cx.current_expansion.id, None);
+                    let expn_id = ExpnId::fresh(None);
                     derives.push(expn_id);
                     invocations.push(Invocation {
                         kind: InvocationKind::Derive { path, item: item.clone() },
@@ -475,11 +475,11 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
         }
 
         if self.cx.current_expansion.depth > self.cx.ecfg.recursion_limit {
-            let info = self.cx.current_expansion.id.expn_info().unwrap();
+            let expn_data = self.cx.current_expansion.id.expn_data();
             let suggested_limit = self.cx.ecfg.recursion_limit * 2;
-            let mut err = self.cx.struct_span_err(info.call_site,
+            let mut err = self.cx.struct_span_err(expn_data.call_site,
                 &format!("recursion limit reached while expanding the macro `{}`",
-                         info.kind.descr()));
+                         expn_data.kind.descr()));
             err.help(&format!(
                 "consider adding a `#![recursion_limit=\"{}\"]` attribute to your crate",
                 suggested_limit));
@@ -759,7 +759,7 @@ impl<'a> Parser<'a> {
             let msg = format!("macro expansion ignores token `{}` and any following",
                               self.this_token_to_string());
             // Avoid emitting backtrace info twice.
-            let def_site_span = self.token.span.with_ctxt(SyntaxContext::empty());
+            let def_site_span = self.token.span.with_ctxt(SyntaxContext::root());
             let mut err = self.diagnostic().struct_span_err(def_site_span, &msg);
             err.span_label(span, "caused by the macro expansion here");
             let msg = format!(
@@ -796,17 +796,20 @@ struct InvocationCollector<'a, 'b> {
 
 impl<'a, 'b> InvocationCollector<'a, 'b> {
     fn collect(&mut self, fragment_kind: AstFragmentKind, kind: InvocationKind) -> AstFragment {
-        // Expansion info for all the collected invocations is set upon their resolution,
+        // Expansion data for all the collected invocations is set upon their resolution,
         // with exception of the derive container case which is not resolved and can get
-        // its expansion info immediately.
-        let expn_info = match &kind {
-            InvocationKind::DeriveContainer { item, .. } => Some(ExpnInfo::default(
-                ExpnKind::Macro(MacroKind::Attr, sym::derive),
-                item.span(), self.cx.parse_sess.edition,
-            )),
+        // its expansion data immediately.
+        let expn_data = match &kind {
+            InvocationKind::DeriveContainer { item, .. } => Some(ExpnData {
+                parent: self.cx.current_expansion.id,
+                ..ExpnData::default(
+                    ExpnKind::Macro(MacroKind::Attr, sym::derive),
+                    item.span(), self.cx.parse_sess.edition,
+                )
+            }),
             _ => None,
         };
-        let expn_id = ExpnId::fresh(self.cx.current_expansion.id, expn_info);
+        let expn_id = ExpnId::fresh(expn_data);
         self.invocations.push(Invocation {
             kind,
             fragment_kind,
@@ -1249,21 +1252,21 @@ impl<'a, 'b> MutVisitor for InvocationCollector<'a, 'b> {
                             let include_info = vec![
                                 ast::NestedMetaItem::MetaItem(
                                     attr::mk_name_value_item_str(
-                                        Ident::with_empty_ctxt(sym::file),
+                                        Ident::with_dummy_span(sym::file),
                                         file,
                                         DUMMY_SP,
                                     ),
                                 ),
                                 ast::NestedMetaItem::MetaItem(
                                     attr::mk_name_value_item_str(
-                                        Ident::with_empty_ctxt(sym::contents),
+                                        Ident::with_dummy_span(sym::contents),
                                         src_interned,
                                         DUMMY_SP,
                                     ),
                                 ),
                             ];
 
-                            let include_ident = Ident::with_empty_ctxt(sym::include);
+                            let include_ident = Ident::with_dummy_span(sym::include);
                             let item = attr::mk_list_item(include_ident, include_info);
                             items.push(ast::NestedMetaItem::MetaItem(item));
                         }
@@ -1325,7 +1328,7 @@ impl<'a, 'b> MutVisitor for InvocationCollector<'a, 'b> {
                 }
             }
 
-            let meta = attr::mk_list_item(Ident::with_empty_ctxt(sym::doc), items);
+            let meta = attr::mk_list_item(Ident::with_dummy_span(sym::doc), items);
             *at = attr::Attribute {
                 span: at.span,
                 id: at.id,
diff --git a/src/libsyntax/ext/proc_macro_server.rs b/src/libsyntax/ext/proc_macro_server.rs
index 36621ce7775..1619fa69941 100644
--- a/src/libsyntax/ext/proc_macro_server.rs
+++ b/src/libsyntax/ext/proc_macro_server.rs
@@ -362,10 +362,10 @@ pub(crate) struct Rustc<'a> {
 impl<'a> Rustc<'a> {
     pub fn new(cx: &'a ExtCtxt<'_>) -> Self {
         // No way to determine def location for a proc macro right now, so use call location.
-        let location = cx.current_expansion.id.expn_info().unwrap().call_site;
+        let location = cx.current_expansion.id.expn_data().call_site;
         let to_span = |transparency| {
             location.with_ctxt(
-                SyntaxContext::empty()
+                SyntaxContext::root()
                     .apply_mark_with_transparency(cx.current_expansion.id, transparency),
             )
         };
@@ -677,7 +677,7 @@ impl server::Span for Rustc<'_> {
         self.sess.source_map().lookup_char_pos(span.lo()).file
     }
     fn parent(&mut self, span: Self::Span) -> Option<Self::Span> {
-        span.ctxt().outer_expn_info().map(|i| i.call_site)
+        span.parent()
     }
     fn source(&mut self, span: Self::Span) -> Self::Span {
         span.source_callsite()
diff --git a/src/libsyntax/parse/lexer/mod.rs b/src/libsyntax/parse/lexer/mod.rs
index e86d4c7fde6..17629d392cd 100644
--- a/src/libsyntax/parse/lexer/mod.rs
+++ b/src/libsyntax/parse/lexer/mod.rs
@@ -4,7 +4,7 @@ use crate::symbol::{sym, Symbol};
 use crate::parse::unescape_error_reporting::{emit_unescape_error, push_escaped_char};
 
 use errors::{FatalError, DiagnosticBuilder};
-use syntax_pos::{BytePos, Pos, Span, NO_EXPANSION};
+use syntax_pos::{BytePos, Pos, Span};
 use rustc_lexer::Base;
 use rustc_lexer::unescape;
 
@@ -84,7 +84,7 @@ impl<'a> StringReader<'a> {
 
 
     fn mk_sp(&self, lo: BytePos, hi: BytePos) -> Span {
-        self.override_span.unwrap_or_else(|| Span::new(lo, hi, NO_EXPANSION))
+        self.override_span.unwrap_or_else(|| Span::with_root_ctxt(lo, hi))
     }
 
     /// Returns the next token, including trivia like whitespace or comments.
diff --git a/src/libsyntax/parse/lexer/tests.rs b/src/libsyntax/parse/lexer/tests.rs
index fc47e4f0b18..94570140996 100644
--- a/src/libsyntax/parse/lexer/tests.rs
+++ b/src/libsyntax/parse/lexer/tests.rs
@@ -1,41 +1,17 @@
 use super::*;
 
-use crate::ast::CrateConfig;
 use crate::symbol::Symbol;
 use crate::source_map::{SourceMap, FilePathMapping};
-use crate::feature_gate::UnstableFeatures;
 use crate::parse::token;
-use crate::diagnostics::plugin::ErrorMap;
 use crate::with_default_globals;
 use std::io;
 use std::path::PathBuf;
-use syntax_pos::{BytePos, Span, NO_EXPANSION, edition::Edition};
-use rustc_data_structures::fx::{FxHashSet, FxHashMap};
-use rustc_data_structures::sync::{Lock, Once};
+use errors::{Handler, emitter::EmitterWriter};
+use syntax_pos::{BytePos, Span};
 
 fn mk_sess(sm: Lrc<SourceMap>) -> ParseSess {
-    let emitter = errors::emitter::EmitterWriter::new(Box::new(io::sink()),
-                                                        Some(sm.clone()),
-                                                        false,
-                                                        false,
-                                                        false);
-    ParseSess {
-        span_diagnostic: errors::Handler::with_emitter(true, None, Box::new(emitter)),
-        unstable_features: UnstableFeatures::from_environment(),
-        config: CrateConfig::default(),
-        included_mod_stack: Lock::new(Vec::new()),
-        source_map: sm,
-        missing_fragment_specifiers: Lock::new(FxHashSet::default()),
-        raw_identifier_spans: Lock::new(Vec::new()),
-        registered_diagnostics: Lock::new(ErrorMap::new()),
-        buffered_lints: Lock::new(vec![]),
-        edition: Edition::from_session(),
-        ambiguous_block_expr_parse: Lock::new(FxHashMap::default()),
-        param_attr_spans: Lock::new(Vec::new()),
-        let_chains_spans: Lock::new(Vec::new()),
-        async_closure_spans: Lock::new(Vec::new()),
-        injected_crate_name: Once::new(),
-    }
+    let emitter = EmitterWriter::new(Box::new(io::sink()), Some(sm.clone()), false, false, false);
+    ParseSess::with_span_handler(Handler::with_emitter(true, None, Box::new(emitter)), sm)
 }
 
 // open a string reader for the given string
@@ -61,7 +37,7 @@ fn t1() {
         let tok1 = string_reader.next_token();
         let tok2 = Token::new(
             mk_ident("fn"),
-            Span::new(BytePos(21), BytePos(23), NO_EXPANSION),
+            Span::with_root_ctxt(BytePos(21), BytePos(23)),
         );
         assert_eq!(tok1.kind, tok2.kind);
         assert_eq!(tok1.span, tok2.span);
@@ -71,7 +47,7 @@ fn t1() {
         assert_eq!(string_reader.pos.clone(), BytePos(28));
         let tok4 = Token::new(
             mk_ident("main"),
-            Span::new(BytePos(24), BytePos(28), NO_EXPANSION),
+            Span::with_root_ctxt(BytePos(24), BytePos(28)),
         );
         assert_eq!(tok3.kind, tok4.kind);
         assert_eq!(tok3.span, tok4.span);
diff --git a/src/libsyntax/parse/lexer/unicode_chars.rs b/src/libsyntax/parse/lexer/unicode_chars.rs
index eaa736c6a35..525b4215aff 100644
--- a/src/libsyntax/parse/lexer/unicode_chars.rs
+++ b/src/libsyntax/parse/lexer/unicode_chars.rs
@@ -3,7 +3,7 @@
 
 use super::StringReader;
 use errors::{Applicability, DiagnosticBuilder};
-use syntax_pos::{BytePos, Pos, Span, NO_EXPANSION, symbol::kw};
+use syntax_pos::{BytePos, Pos, Span, symbol::kw};
 use crate::parse::token;
 
 #[rustfmt::skip] // for line breaks
@@ -343,7 +343,7 @@ crate fn check_for_substitution<'a>(
         None => return None,
     };
 
-    let span = Span::new(pos, pos + Pos::from_usize(ch.len_utf8()), NO_EXPANSION);
+    let span = Span::with_root_ctxt(pos, pos + Pos::from_usize(ch.len_utf8()));
 
     let (ascii_name, token) = match ASCII_ARRAY.iter().find(|&&(c, _, _)| c == ascii_char) {
         Some((_ascii_char, ascii_name, token)) => (ascii_name, token),
@@ -362,10 +362,9 @@ crate fn check_for_substitution<'a>(
             ascii_char, ascii_name
         );
         err.span_suggestion(
-            Span::new(
+            Span::with_root_ctxt(
                 pos,
                 pos + Pos::from_usize('“'.len_utf8() + s.len() + '”'.len_utf8()),
-                NO_EXPANSION,
             ),
             &msg,
             format!("\"{}\"", s),
diff --git a/src/libsyntax/parse/mod.rs b/src/libsyntax/parse/mod.rs
index 80aa7a35266..26f78b9c5c7 100644
--- a/src/libsyntax/parse/mod.rs
+++ b/src/libsyntax/parse/mod.rs
@@ -16,6 +16,7 @@ use errors::{Applicability, FatalError, Level, Handler, ColorConfig, Diagnostic,
 use rustc_data_structures::sync::{Lrc, Lock, Once};
 use syntax_pos::{Span, SourceFile, FileName, MultiSpan};
 use syntax_pos::edition::Edition;
+use syntax_pos::hygiene::ExpnId;
 
 use rustc_data_structures::fx::{FxHashSet, FxHashMap};
 use std::borrow::Cow;
@@ -86,7 +87,7 @@ impl ParseSess {
             included_mod_stack: Lock::new(vec![]),
             source_map,
             buffered_lints: Lock::new(vec![]),
-            edition: Edition::from_session(),
+            edition: ExpnId::root().expn_data().edition,
             ambiguous_block_expr_parse: Lock::new(FxHashMap::default()),
             param_attr_spans: Lock::new(Vec::new()),
             let_chains_spans: Lock::new(Vec::new()),
diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs
index 2286e74e633..89725d8b339 100644
--- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -13,7 +13,6 @@ mod generics;
 use crate::ast::{self, AttrStyle, Attribute, Arg, BindingMode, StrStyle, SelfKind};
 use crate::ast::{FnDecl, Ident, IsAsync, MacDelimiter, Mutability, TyKind};
 use crate::ast::{Visibility, VisibilityKind, Unsafety, CrateSugar};
-use crate::ext::hygiene::SyntaxContext;
 use crate::source_map::{self, respan};
 use crate::parse::{SeqSep, literal, token};
 use crate::parse::lexer::UnmatchedBrace;
@@ -1101,7 +1100,7 @@ impl<'a> Parser<'a> {
 
     crate fn process_potential_macro_variable(&mut self) {
         self.token = match self.token.kind {
-            token::Dollar if self.token.span.ctxt() != SyntaxContext::empty() &&
+            token::Dollar if self.token.span.from_expansion() &&
                              self.look_ahead(1, |t| t.is_ident()) => {
                 self.bump();
                 let name = match self.token.kind {
diff --git a/src/libsyntax/parse/parser/module.rs b/src/libsyntax/parse/parser/module.rs
index 58a7ffba948..3f6f87b1c44 100644
--- a/src/libsyntax/parse/parser/module.rs
+++ b/src/libsyntax/parse/parser/module.rs
@@ -60,7 +60,7 @@ impl<'a> Parser<'a> {
                 // Record that we fetched the mod from an external file
                 if warn {
                     let attr = attr::mk_attr_outer(
-                        attr::mk_word_item(Ident::with_empty_ctxt(sym::warn_directory_ownership)));
+                        attr::mk_word_item(Ident::with_dummy_span(sym::warn_directory_ownership)));
                     attr::mark_known(&attr);
                     attrs.push(attr);
                 }
diff --git a/src/libsyntax/parse/tests.rs b/src/libsyntax/parse/tests.rs
index 9edc83a3594..6a789ef99d6 100644
--- a/src/libsyntax/parse/tests.rs
+++ b/src/libsyntax/parse/tests.rs
@@ -12,7 +12,7 @@ use crate::symbol::{kw, sym};
 use crate::tests::{matches_codepattern, string_to_stream, with_error_checking_parse};
 use crate::tokenstream::{DelimSpan, TokenTree, TokenStream};
 use crate::with_default_globals;
-use syntax_pos::{Span, BytePos, Pos, NO_EXPANSION};
+use syntax_pos::{Span, BytePos, Pos};
 
 use std::path::PathBuf;
 
@@ -27,7 +27,7 @@ fn parse_item_from_source_str(name: FileName, source: String, sess: &ParseSess)
 
 // produce a syntax_pos::span
 fn sp(a: u32, b: u32) -> Span {
-    Span::new(BytePos(a), BytePos(b), NO_EXPANSION)
+    Span::with_root_ctxt(BytePos(a), BytePos(b))
 }
 
 /// Parse a string, return an expr
diff --git a/src/libsyntax/print/pprust.rs b/src/libsyntax/print/pprust.rs
index 5955b913842..8a7009828bc 100644
--- a/src/libsyntax/print/pprust.rs
+++ b/src/libsyntax/print/pprust.rs
@@ -123,13 +123,13 @@ pub fn print_crate<'a>(cm: &'a SourceMap,
         // of the feature gate, so we fake them up here.
 
         // #![feature(prelude_import)]
-        let pi_nested = attr::mk_nested_word_item(ast::Ident::with_empty_ctxt(sym::prelude_import));
-        let list = attr::mk_list_item(ast::Ident::with_empty_ctxt(sym::feature), vec![pi_nested]);
+        let pi_nested = attr::mk_nested_word_item(ast::Ident::with_dummy_span(sym::prelude_import));
+        let list = attr::mk_list_item(ast::Ident::with_dummy_span(sym::feature), vec![pi_nested]);
         let fake_attr = attr::mk_attr_inner(list);
         s.print_attribute(&fake_attr);
 
         // #![no_std]
-        let no_std_meta = attr::mk_word_item(ast::Ident::with_empty_ctxt(sym::no_std));
+        let no_std_meta = attr::mk_word_item(ast::Ident::with_dummy_span(sym::no_std));
         let fake_attr = attr::mk_attr_inner(no_std_meta);
         s.print_attribute(&fake_attr);
     }
diff --git a/src/libsyntax/source_map.rs b/src/libsyntax/source_map.rs
index 74cab00d3c1..940687cb5d4 100644
--- a/src/libsyntax/source_map.rs
+++ b/src/libsyntax/source_map.rs
@@ -8,7 +8,7 @@
 //! information, source code snippets, etc.
 
 pub use syntax_pos::*;
-pub use syntax_pos::hygiene::{ExpnKind, ExpnInfo};
+pub use syntax_pos::hygiene::{ExpnKind, ExpnData};
 
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::stable_hasher::StableHasher;
@@ -29,14 +29,15 @@ mod tests;
 
 /// Returns the span itself if it doesn't come from a macro expansion,
 /// otherwise return the call site span up to the `enclosing_sp` by
-/// following the `expn_info` chain.
+/// following the `expn_data` chain.
 pub fn original_sp(sp: Span, enclosing_sp: Span) -> Span {
-    let call_site1 = sp.ctxt().outer_expn_info().map(|ei| ei.call_site);
-    let call_site2 = enclosing_sp.ctxt().outer_expn_info().map(|ei| ei.call_site);
-    match (call_site1, call_site2) {
-        (None, _) => sp,
-        (Some(call_site1), Some(call_site2)) if call_site1 == call_site2 => sp,
-        (Some(call_site1), _) => original_sp(call_site1, enclosing_sp),
+    let expn_data1 = sp.ctxt().outer_expn_data();
+    let expn_data2 = enclosing_sp.ctxt().outer_expn_data();
+    if expn_data1.is_root() ||
+       !expn_data2.is_root() && expn_data1.call_site == expn_data2.call_site {
+        sp
+    } else {
+        original_sp(expn_data1.call_site, enclosing_sp)
     }
 }
 
diff --git a/src/libsyntax/source_map/tests.rs b/src/libsyntax/source_map/tests.rs
index 427e86b56e1..c7b8332c53e 100644
--- a/src/libsyntax/source_map/tests.rs
+++ b/src/libsyntax/source_map/tests.rs
@@ -91,7 +91,7 @@ fn t6() {
 fn t7() {
     // Test span_to_lines for a span ending at the end of source_file
     let sm = init_source_map();
-    let span = Span::new(BytePos(12), BytePos(23), NO_EXPANSION);
+    let span = Span::with_root_ctxt(BytePos(12), BytePos(23));
     let file_lines = sm.span_to_lines(span).unwrap();
 
     assert_eq!(file_lines.file.name, PathBuf::from("blork.rs").into());
@@ -107,7 +107,7 @@ fn span_from_selection(input: &str, selection: &str) -> Span {
     assert_eq!(input.len(), selection.len());
     let left_index = selection.find('~').unwrap() as u32;
     let right_index = selection.rfind('~').map(|x|x as u32).unwrap_or(left_index);
-    Span::new(BytePos(left_index), BytePos(right_index + 1), NO_EXPANSION)
+    Span::with_root_ctxt(BytePos(left_index), BytePos(right_index + 1))
 }
 
 /// Tests span_to_snippet and span_to_lines for a span converting 3
@@ -137,7 +137,7 @@ fn span_to_snippet_and_lines_spanning_multiple_lines() {
 fn t8() {
     // Test span_to_snippet for a span ending at the end of source_file
     let sm = init_source_map();
-    let span = Span::new(BytePos(12), BytePos(23), NO_EXPANSION);
+    let span = Span::with_root_ctxt(BytePos(12), BytePos(23));
     let snippet = sm.span_to_snippet(span);
 
     assert_eq!(snippet, Ok("second line".to_string()));
@@ -147,7 +147,7 @@ fn t8() {
 fn t9() {
     // Test span_to_str for a span ending at the end of source_file
     let sm = init_source_map();
-    let span = Span::new(BytePos(12), BytePos(23), NO_EXPANSION);
+    let span = Span::with_root_ctxt(BytePos(12), BytePos(23));
     let sstr =  sm.span_to_string(span);
 
     assert_eq!(sstr, "blork.rs:2:1: 2:12");
@@ -198,10 +198,9 @@ impl SourceMapExtension for SourceMap {
             let lo = hi + offset;
             hi = lo + substring.len();
             if i == n {
-                let span = Span::new(
+                let span = Span::with_root_ctxt(
                     BytePos(lo as u32 + file.start_pos.0),
                     BytePos(hi as u32 + file.start_pos.0),
-                    NO_EXPANSION,
                 );
                 assert_eq!(&self.span_to_snippet(span).unwrap()[..],
                         substring);
diff --git a/src/libsyntax/tests.rs b/src/libsyntax/tests.rs
index cff034fdeb1..4c0e1e3704d 100644
--- a/src/libsyntax/tests.rs
+++ b/src/libsyntax/tests.rs
@@ -9,7 +9,7 @@ use crate::with_default_globals;
 use errors::emitter::EmitterWriter;
 use errors::Handler;
 use rustc_data_structures::sync::Lrc;
-use syntax_pos::{BytePos, NO_EXPANSION, Span, MultiSpan};
+use syntax_pos::{BytePos, Span, MultiSpan};
 
 use std::io;
 use std::io::prelude::*;
@@ -169,7 +169,7 @@ fn make_span(file_text: &str, start: &Position, end: &Position) -> Span {
     let start = make_pos(file_text, start);
     let end = make_pos(file_text, end) + end.string.len(); // just after matching thing ends
     assert!(start <= end);
-    Span::new(BytePos(start as u32), BytePos(end as u32), NO_EXPANSION)
+    Span::with_root_ctxt(BytePos(start as u32), BytePos(end as u32))
 }
 
 fn make_pos(file_text: &str, pos: &Position) -> usize {
diff --git a/src/libsyntax/tokenstream/tests.rs b/src/libsyntax/tokenstream/tests.rs
index 72e22a49876..5017e5f5424 100644
--- a/src/libsyntax/tokenstream/tests.rs
+++ b/src/libsyntax/tokenstream/tests.rs
@@ -3,14 +3,14 @@ use super::*;
 use crate::ast::Name;
 use crate::with_default_globals;
 use crate::tests::string_to_stream;
-use syntax_pos::{Span, BytePos, NO_EXPANSION};
+use syntax_pos::{Span, BytePos};
 
 fn string_to_ts(string: &str) -> TokenStream {
     string_to_stream(string.to_owned())
 }
 
 fn sp(a: u32, b: u32) -> Span {
-    Span::new(BytePos(a), BytePos(b), NO_EXPANSION)
+    Span::with_root_ctxt(BytePos(a), BytePos(b))
 }
 
 #[test]