Hygiene serialization implementation

32 files changed, 929 insertions, 284 deletions

diff --git a/src/librustc_ast_lowering/expr.rs b/src/librustc_ast_lowering/expr.rs
index 201972fcf26..abd5df537db 100644
--- a/src/librustc_ast_lowering/expr.rs
+++ b/src/librustc_ast_lowering/expr.rs
@@ -9,7 +9,8 @@ use rustc_data_structures::thin_vec::ThinVec;
 use rustc_errors::struct_span_err;
 use rustc_hir as hir;
 use rustc_hir::def::Res;
-use rustc_span::source_map::{respan, DesugaringKind, ForLoopLoc, Span, Spanned};
+use rustc_span::hygiene::ForLoopLoc;
+use rustc_span::source_map::{respan, DesugaringKind, Span, Spanned};
 use rustc_span::symbol::{sym, Ident, Symbol};
 use rustc_target::asm;
 use std::collections::hash_map::Entry;
diff --git a/src/librustc_expand/base.rs b/src/librustc_expand/base.rs
index 64e2d5b3a46..daa75d42324 100644
--- a/src/librustc_expand/base.rs
+++ b/src/librustc_expand/base.rs
@@ -13,7 +13,7 @@ use rustc_data_structures::sync::{self, Lrc};
 use rustc_errors::{DiagnosticBuilder, ErrorReported};
 use rustc_parse::{self, nt_to_tokenstream, parser, MACRO_ARGUMENTS};
 use rustc_session::{parse::ParseSess, Limit};
-use rustc_span::def_id::DefId;
+use rustc_span::def_id::{DefId, LOCAL_CRATE};
 use rustc_span::edition::Edition;
 use rustc_span::hygiene::{AstPass, ExpnData, ExpnId, ExpnKind};
 use rustc_span::source_map::SourceMap;
@@ -873,6 +873,8 @@ impl SyntaxExtension {
             local_inner_macros: self.local_inner_macros,
             edition: self.edition,
             macro_def_id,
+            krate: LOCAL_CRATE,
+            orig_id: None,
         }
     }
 }
diff --git a/src/librustc_expand/expand.rs b/src/librustc_expand/expand.rs
index bd7a094c5e3..4a40f799c15 100644
--- a/src/librustc_expand/expand.rs
+++ b/src/librustc_expand/expand.rs
@@ -1,7 +1,7 @@
 use crate::base::*;
 use crate::config::StripUnconfigured;
 use crate::configure;
-use crate::hygiene::{ExpnData, ExpnId, ExpnKind, SyntaxContext};
+use crate::hygiene::{ExpnData, ExpnKind, SyntaxContext};
 use crate::mbe::macro_rules::annotate_err_with_kind;
 use crate::module::{parse_external_mod, push_directory, Directory, DirectoryOwnership};
 use crate::placeholders::{placeholder, PlaceholderExpander};
@@ -27,7 +27,7 @@ use rustc_session::parse::{feature_err, ParseSess};
 use rustc_session::Limit;
 use rustc_span::source_map::respan;
 use rustc_span::symbol::{sym, Ident, Symbol};
-use rustc_span::{FileName, Span, DUMMY_SP};
+use rustc_span::{ExpnId, FileName, Span, DUMMY_SP};
 
 use smallvec::{smallvec, SmallVec};
 use std::io::ErrorKind;
diff --git a/src/librustc_metadata/creader.rs b/src/librustc_metadata/creader.rs
index 0d2101cb2cb..724b4123fab 100644
--- a/src/librustc_metadata/creader.rs
+++ b/src/librustc_metadata/creader.rs
@@ -307,11 +307,16 @@ impl<'a> CrateLoader<'a> {
         let private_dep =
             self.sess.opts.externs.get(&name.as_str()).map(|e| e.is_private_dep).unwrap_or(false);
 
-        info!("register crate `{}` (private_dep = {})", crate_root.name(), private_dep);
-
         // Claim this crate number and cache it
         let cnum = self.cstore.alloc_new_crate_num();
 
+        info!(
+            "register crate `{}` (cnum = {}. private_dep = {})",
+            crate_root.name(),
+            cnum,
+            private_dep
+        );
+
         // Maintain a reference to the top most crate.
         // Stash paths for top-most crate locally if necessary.
         let crate_paths;
@@ -339,22 +344,21 @@ impl<'a> CrateLoader<'a> {
             None
         };
 
-        self.cstore.set_crate_data(
+        let crate_metadata = CrateMetadata::new(
+            self.sess,
+            metadata,
+            crate_root,
+            raw_proc_macros,
             cnum,
-            CrateMetadata::new(
-                self.sess,
-                metadata,
-                crate_root,
-                raw_proc_macros,
-                cnum,
-                cnum_map,
-                dep_kind,
-                source,
-                private_dep,
-                host_hash,
-            ),
+            cnum_map,
+            dep_kind,
+            source,
+            private_dep,
+            host_hash,
         );
 
+        self.cstore.set_crate_data(cnum, crate_metadata);
+
         Ok(cnum)
     }
 
@@ -569,6 +573,8 @@ impl<'a> CrateLoader<'a> {
             let cnum = self.maybe_resolve_crate(dep.name, dep_kind, Some((root, &dep)))?;
             crate_num_map.push(cnum);
         }
+
+        debug!("resolve_crate_deps: cnum_map for {:?} is {:?}", krate, crate_num_map);
         Ok(crate_num_map)
     }
 
diff --git a/src/librustc_metadata/lib.rs b/src/librustc_metadata/lib.rs
index 76e39a476c6..d4add2ab7ad 100644
--- a/src/librustc_metadata/lib.rs
+++ b/src/librustc_metadata/lib.rs
@@ -9,6 +9,7 @@
 #![feature(proc_macro_internals)]
 #![feature(min_specialization)]
 #![feature(stmt_expr_attributes)]
+#![feature(never_type)]
 #![recursion_limit = "256"]
 
 extern crate proc_macro;
diff --git a/src/librustc_metadata/rmeta/decoder.rs b/src/librustc_metadata/rmeta/decoder.rs
index a6d708ebe90..7d428840cc9 100644
--- a/src/librustc_metadata/rmeta/decoder.rs
+++ b/src/librustc_metadata/rmeta/decoder.rs
@@ -32,18 +32,21 @@ use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_middle::util::common::record_time;
 use rustc_serialize::{opaque, Decodable, Decoder, SpecializedDecoder, UseSpecializedDecodable};
 use rustc_session::Session;
+use rustc_span::hygiene::ExpnDataDecodeMode;
 use rustc_span::source_map::{respan, Spanned};
 use rustc_span::symbol::{sym, Ident, Symbol};
-use rustc_span::{self, hygiene::MacroKind, BytePos, Pos, Span, DUMMY_SP};
+use rustc_span::{self, hygiene::MacroKind, BytePos, ExpnId, Pos, Span, SyntaxContext, DUMMY_SP};
 
 use log::debug;
 use proc_macro::bridge::client::ProcMacro;
+use std::cell::Cell;
 use std::io;
 use std::mem;
 use std::num::NonZeroUsize;
 use std::path::Path;
 
 pub use cstore_impl::{provide, provide_extern};
+use rustc_span::hygiene::HygieneContext;
 
 mod cstore_impl;
 
@@ -106,6 +109,13 @@ crate struct CrateMetadata {
     /// The hash for the host proc macro. Used to support `-Z dual-proc-macro`.
     host_hash: Option<Svh>,
 
+    /// Additional data used for decoding `HygieneData` (e.g. `SyntaxContext`
+    /// and `ExpnId`).
+    /// Note that we store a `HygieneContext` for each `CrateMetadat`. This is
+    /// because `SyntaxContext` ids are not globally unique, so we need
+    /// to track which ids we've decoded on a per-crate basis.
+    hygiene_context: HygieneContext,
+
     // --- Data used only for improving diagnostics ---
     /// Information about the `extern crate` item or path that caused this crate to be loaded.
     /// If this is `None`, then the crate was injected (e.g., by the allocator).
@@ -411,6 +421,7 @@ impl<'a, 'tcx> SpecializedDecoder<Span> for DecodeContext<'a, 'tcx> {
 
         let lo = BytePos::decode(self)?;
         let len = BytePos::decode(self)?;
+        let ctxt = SyntaxContext::decode(self)?;
         let hi = lo + len;
 
         let sess = if let Some(sess) = self.sess {
@@ -524,7 +535,7 @@ impl<'a, 'tcx> SpecializedDecoder<Span> for DecodeContext<'a, 'tcx> {
         let hi =
             (hi + source_file.translated_source_file.start_pos) - source_file.original_start_pos;
 
-        Ok(Span::with_root_ctxt(lo, hi))
+        Ok(Span::new(lo, hi, ctxt))
     }
 }
 
@@ -1120,6 +1131,14 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
         !self.is_proc_macro(id) && self.root.tables.mir.get(self, id).is_some()
     }
 
+    fn module_expansion(&self, id: DefIndex, sess: &Session) -> ExpnId {
+        if let EntryKind::Mod(m) = self.kind(id) {
+            m.decode((self, sess)).expansion
+        } else {
+            panic!("Expected module, found {:?}", self.local_def_id(id))
+        }
+    }
+
     fn get_optimized_mir(&self, tcx: TyCtxt<'tcx>, id: DefIndex) -> Body<'tcx> {
         self.root
             .tables
@@ -1652,6 +1671,7 @@ impl CrateMetadata {
             private_dep,
             host_hash,
             extern_crate: Lock::new(None),
+            hygiene_context: HygieneContext::new(),
         }
     }
 
@@ -1784,3 +1804,57 @@ fn macro_kind(raw: &ProcMacro) -> MacroKind {
         ProcMacro::Bang { .. } => MacroKind::Bang,
     }
 }
+
+impl<'a, 'tcx> SpecializedDecoder<SyntaxContext> for DecodeContext<'a, 'tcx> {
+    fn specialized_decode(&mut self) -> Result<SyntaxContext, Self::Error> {
+        let cdata = self.cdata();
+        let sess = self.sess.unwrap();
+        let cname = cdata.root.name;
+        rustc_span::hygiene::decode_syntax_context(self, &cdata.hygiene_context, |_, id| {
+            debug!("SpecializedDecoder<SyntaxContext>: decoding {}", id);
+            Ok(cdata
+                .root
+                .syntax_contexts
+                .get(&cdata, id)
+                .unwrap_or_else(|| panic!("Missing SyntaxContext {:?} for crate {:?}", id, cname))
+                .decode((&cdata, sess)))
+        })
+    }
+}
+
+impl<'a, 'tcx> SpecializedDecoder<ExpnId> for DecodeContext<'a, 'tcx> {
+    fn specialized_decode(&mut self) -> Result<ExpnId, Self::Error> {
+        let local_cdata = self.cdata();
+        let sess = self.sess.unwrap();
+        let expn_cnum = Cell::new(None);
+        let get_ctxt = |cnum| {
+            expn_cnum.set(Some(cnum));
+            if cnum == LOCAL_CRATE {
+                &local_cdata.hygiene_context
+            } else {
+                &local_cdata.cstore.get_crate_data(cnum).cdata.hygiene_context
+            }
+        };
+
+        rustc_span::hygiene::decode_expn_id(
+            self,
+            ExpnDataDecodeMode::Metadata(get_ctxt),
+            |_this, index| {
+                let cnum = expn_cnum.get().unwrap();
+                // Lookup local `ExpnData`s in our own crate data. Foreign `ExpnData`s
+                // are stored in the owning crate, to avoid duplication.
+                let crate_data = if cnum == LOCAL_CRATE {
+                    local_cdata
+                } else {
+                    local_cdata.cstore.get_crate_data(cnum)
+                };
+                Ok(crate_data
+                    .root
+                    .expn_data
+                    .get(&crate_data, index)
+                    .unwrap()
+                    .decode((&crate_data, sess)))
+            },
+        )
+    }
+}
diff --git a/src/librustc_metadata/rmeta/decoder/cstore_impl.rs b/src/librustc_metadata/rmeta/decoder/cstore_impl.rs
index 9160327c1d1..e51862be9a8 100644
--- a/src/librustc_metadata/rmeta/decoder/cstore_impl.rs
+++ b/src/librustc_metadata/rmeta/decoder/cstore_impl.rs
@@ -21,9 +21,10 @@ use rustc_middle::ty::{self, TyCtxt};
 use rustc_session::utils::NativeLibKind;
 use rustc_session::{CrateDisambiguator, Session};
 use rustc_span::source_map::{self, Span, Spanned};
-use rustc_span::symbol::{Ident, Symbol};
+use rustc_span::symbol::Symbol;
 
 use rustc_data_structures::sync::Lrc;
+use rustc_span::ExpnId;
 use smallvec::SmallVec;
 use std::any::Any;
 
@@ -417,13 +418,7 @@ impl CStore {
             attr::mark_used(attr);
         }
 
-        let ident = data
-            .def_key(id.index)
-            .disambiguated_data
-            .data
-            .get_opt_name()
-            .map(Ident::with_dummy_span) // FIXME: cross-crate hygiene
-            .expect("no name in load_macro");
+        let ident = data.item_ident(id.index, sess);
 
         LoadedMacro::MacroDef(
             ast::Item {
@@ -454,6 +449,10 @@ impl CStore {
     pub fn item_generics_num_lifetimes(&self, def_id: DefId, sess: &Session) -> usize {
         self.get_crate_data(def_id.krate).get_generics(def_id.index, sess).own_counts().lifetimes
     }
+
+    pub fn module_expansion_untracked(&self, def_id: DefId, sess: &Session) -> ExpnId {
+        self.get_crate_data(def_id.krate).module_expansion(def_id.index, sess)
+    }
 }
 
 impl CrateStore for CStore {
diff --git a/src/librustc_metadata/rmeta/encoder.rs b/src/librustc_metadata/rmeta/encoder.rs
index 186828b6a19..6539c13d812 100644
--- a/src/librustc_metadata/rmeta/encoder.rs
+++ b/src/librustc_metadata/rmeta/encoder.rs
@@ -1,4 +1,4 @@
-use crate::rmeta::table::FixedSizeEncoding;
+use crate::rmeta::table::{FixedSizeEncoding, TableBuilder};
 use crate::rmeta::*;
 
 use log::{debug, trace};
@@ -30,9 +30,10 @@ use rustc_middle::ty::codec::{self as ty_codec, TyEncoder};
 use rustc_middle::ty::{self, SymbolName, Ty, TyCtxt};
 use rustc_serialize::{opaque, Encodable, Encoder, SpecializedEncoder, UseSpecializedEncodable};
 use rustc_session::config::CrateType;
+use rustc_span::hygiene::ExpnDataEncodeMode;
 use rustc_span::source_map::Spanned;
 use rustc_span::symbol::{sym, Ident, Symbol};
-use rustc_span::{self, ExternalSource, FileName, SourceFile, Span};
+use rustc_span::{self, ExternalSource, FileName, SourceFile, Span, SyntaxContext};
 use rustc_target::abi::VariantIdx;
 use std::hash::Hash;
 use std::num::NonZeroUsize;
@@ -66,6 +67,15 @@ struct EncodeContext<'tcx> {
     // with a result containing a foreign `Span`.
     required_source_files: Option<GrowableBitSet<usize>>,
     is_proc_macro: bool,
+    /// All `SyntaxContexts` for which we have writen `SyntaxContextData` into crate metadata.
+    /// This is `None` after we finish encoding `SyntaxContexts`, to ensure
+    /// that we don't accidentally try to encode any more `SyntaxContexts`
+    serialized_ctxts: Option<FxHashSet<SyntaxContext>>,
+    /// The `SyntaxContexts` that we have serialized (e.g. as a result of encoding `Spans`)
+    /// in the most recent 'round' of serializnig. Serializing `SyntaxContextData`
+    /// may cause us to serialize more `SyntaxContext`s, so serialize in a loop
+    /// until we reach a fixed point.
+    latest_ctxts: Option<FxHashSet<SyntaxContext>>,
 }
 
 macro_rules! encoder_methods {
@@ -150,6 +160,21 @@ impl<'tcx> SpecializedEncoder<DefId> for EncodeContext<'tcx> {
     }
 }
 
+impl<'tcx> SpecializedEncoder<SyntaxContext> for EncodeContext<'tcx> {
+    fn specialized_encode(&mut self, ctxt: &SyntaxContext) -> Result<(), Self::Error> {
+        if !self.serialized_ctxts.as_ref().unwrap().contains(ctxt) {
+            self.latest_ctxts.as_mut().unwrap().insert(*ctxt);
+        }
+        rustc_span::hygiene::raw_encode_syntax_context(*ctxt, self)
+    }
+}
+
+impl<'tcx> SpecializedEncoder<ExpnId> for EncodeContext<'tcx> {
+    fn specialized_encode(&mut self, expn: &ExpnId) -> Result<(), Self::Error> {
+        rustc_span::hygiene::raw_encode_expn_id(*expn, ExpnDataEncodeMode::Metadata, self)
+    }
+}
+
 impl<'tcx> SpecializedEncoder<DefIndex> for EncodeContext<'tcx> {
     #[inline]
     fn specialized_encode(&mut self, def_index: &DefIndex) -> Result<(), Self::Error> {
@@ -234,15 +259,24 @@ impl<'tcx> SpecializedEncoder<Span> for EncodeContext<'tcx> {
         let len = hi - lo;
         len.encode(self)?;
 
+        // FIXME: Once #69976 is merged, treat proc-macros normally
+        // Currently, we can't encode `SyntaxContextData` for proc-macro crates,
+        // since the `SyntaxContextData`/`ExpnData` might reference `DefIds` from
+        // dependencies (which are not currently loaded during decoding).
+        if self.is_proc_macro {
+            SyntaxContext::root().encode(self)?;
+        } else {
+            span.ctxt.encode(self)?;
+        }
+
         if tag == TAG_VALID_SPAN_FOREIGN {
             // This needs to be two lines to avoid holding the `self.source_file_cache`
             // while calling `cnum.encode(self)`
             let cnum = self.source_file_cache.0.cnum;
             cnum.encode(self)?;
         }
-        Ok(())
 
-        // Don't encode the expansion context.
+        Ok(())
     }
 }
 
@@ -478,6 +512,7 @@ impl<'tcx> EncodeContext<'tcx> {
 
         let mut i = self.position();
 
+        // Encode the crate deps
         let crate_deps = self.encode_crate_deps();
         let dylib_dependency_formats = self.encode_dylib_dependency_formats();
         let dep_bytes = self.position() - i;
@@ -556,12 +591,23 @@ impl<'tcx> EncodeContext<'tcx> {
         let proc_macro_data_bytes = self.position() - i;
 
         // Encode exported symbols info. This is prefetched in `encode_metadata` so we encode
-        // this late to give the prefetching as much time as possible to complete.
+        // this as late as possible to give the prefetching as much time as possible to complete.
         i = self.position();
         let exported_symbols = tcx.exported_symbols(LOCAL_CRATE);
         let exported_symbols = self.encode_exported_symbols(&exported_symbols);
         let exported_symbols_bytes = self.position() - i;
 
+        // Encode the hygiene data,
+        // IMPORTANT: this *must* be the last thing that we encode (other than `SourceMap`). The process
+        // of encoding other items (e.g. `optimized_mir`) may cause us to load
+        // data from the incremental cache. If this causes us to deserialize a `Span`,
+        // then we may load additional `SyntaxContext`s into the global `HygieneData`.
+        // Therefore, we need to encode the hygiene data last to ensure that we encode
+        // any `SyntaxContext`s that might be used.
+        i = self.position();
+        let (syntax_contexts, syntax_bytes, expn_data, expn_bytes) = self.encode_hygiene();
+        let hygiene_bytes = self.position() - i;
+
         // Encode source_map. This needs to be done last,
         // since encoding `Span`s tells us which `SourceFiles` we actually
         // need to encode.
@@ -618,6 +664,8 @@ impl<'tcx> EncodeContext<'tcx> {
             exported_symbols,
             interpret_alloc_index,
             tables,
+            syntax_contexts,
+            expn_data,
         });
 
         let total_bytes = self.position();
@@ -643,6 +691,9 @@ impl<'tcx> EncodeContext<'tcx> {
             println!(" proc-macro-data-bytes: {}", proc_macro_data_bytes);
             println!("            item bytes: {}", item_bytes);
             println!("           table bytes: {}", tables_bytes);
+            println!("         hygiene bytes: {}", hygiene_bytes);
+            println!("   SyntaxContext bytes: {}", syntax_bytes);
+            println!("          ExpnId bytes: {}", expn_bytes);
             println!("            zero bytes: {}", zero_bytes);
             println!("           total bytes: {}", total_bytes);
         }
@@ -752,11 +803,12 @@ impl EncodeContext<'tcx> {
         vis: &hir::Visibility<'_>,
     ) {
         let tcx = self.tcx;
-        let def_id = tcx.hir().local_def_id(id);
+        let local_def_id = tcx.hir().local_def_id(id);
+        let def_id = local_def_id.to_def_id();
         debug!("EncodeContext::encode_info_for_mod({:?})", def_id);
 
         let data = ModData {
-            reexports: match tcx.module_exports(def_id) {
+            reexports: match tcx.module_exports(local_def_id) {
                 Some(exports) => {
                     let hir_map = self.tcx.hir();
                     self.lazy(
@@ -767,10 +819,9 @@ impl EncodeContext<'tcx> {
                 }
                 _ => Lazy::empty(),
             },
+            expansion: tcx.hir().definitions().expansion_that_defined(local_def_id),
         };
 
-        let def_id = def_id.to_def_id();
-
         record!(self.tables.kind[def_id] <- EntryKind::Mod(self.lazy(data)));
         record!(self.tables.visibility[def_id] <- ty::Visibility::from_hir(vis, id, self.tcx));
         record!(self.tables.span[def_id] <- self.tcx.def_span(def_id));
@@ -1425,6 +1476,77 @@ impl EncodeContext<'tcx> {
         self.lazy(foreign_modules.iter().cloned())
     }
 
+    fn encode_hygiene(&mut self) -> (SyntaxContextTable, usize, ExpnDataTable, usize) {
+        let mut syntax_contexts: TableBuilder<_, _> = Default::default();
+        let mut expn_data_table: TableBuilder<_, _> = Default::default();
+
+        let mut i = self.position();
+        // We need to encode the `ExpnData` *before* we encode
+        // the `SyntaxContextData`, since encoding `ExpnData` may cause
+        // us to use more `SyntaxContexts` when we encode the spans stored
+        // inside `ExpnData`
+        rustc_span::hygiene::for_all_expn_data(|index, expn_data| {
+            // Don't encode the ExpnData for ExpnIds from foreign crates.
+            // The crate that defines the ExpnId will store the ExpnData,
+            // and the metadata decoder will look it from from that crate via the CStore
+            if expn_data.krate == LOCAL_CRATE {
+                expn_data_table.set(index, self.lazy(expn_data));
+            }
+            Ok::<(), !>(())
+        })
+        .unwrap();
+
+        let expn_bytes = self.position() - i;
+
+        i = self.position();
+        let mut num_serialized = 0;
+
+        // When we serialize a `SyntaxContextData`, we may end up serializing
+        // a `SyntaxContext` that we haven't seen before. Therefore,
+        while !self.latest_ctxts.as_ref().unwrap().is_empty() {
+            debug!(
+                "encode_hygiene: Serializing a round of {:?} SyntaxContextDatas: {:?}",
+                self.latest_ctxts.as_ref().unwrap().len(),
+                self.latest_ctxts.as_ref().unwrap()
+            );
+
+            // Consume the current round of SyntaxContexts.
+            let latest = self.latest_ctxts.replace(FxHashSet::default()).unwrap();
+
+            // It's fine to iterate over a HashMap, because thw serialization
+            // of the table that we insert data into doesn't depend on insertion
+            // order
+            rustc_span::hygiene::for_all_data_in(latest.into_iter(), |(index, ctxt, data)| {
+                if self.serialized_ctxts.as_mut().unwrap().insert(ctxt) {
+                    syntax_contexts.set(index, self.lazy(data));
+                    num_serialized += 1;
+                }
+                Ok::<_, !>(())
+            })
+            .unwrap();
+        }
+        debug!("encode_hygiene: Done serializing SyntaxContextData");
+        let syntax_bytes = self.position() - i;
+
+        let total = rustc_span::hygiene::num_syntax_ctxts();
+        debug!(
+            "encode_hygiene: stored {}/{} ({})",
+            num_serialized,
+            total,
+            (num_serialized as f32) / (total as f32)
+        );
+
+        self.serialized_ctxts.take();
+        self.latest_ctxts.take();
+
+        (
+            syntax_contexts.encode(&mut self.opaque),
+            syntax_bytes,
+            expn_data_table.encode(&mut self.opaque),
+            expn_bytes,
+        )
+    }
+
     fn encode_proc_macros(&mut self) -> Option<Lazy<[DefIndex]>> {
         let is_proc_macro = self.tcx.sess.crate_types().contains(&CrateType::ProcMacro);
         if is_proc_macro {
@@ -1919,6 +2041,8 @@ fn encode_metadata_impl(tcx: TyCtxt<'_>) -> EncodedMetadata {
         interpret_allocs_inverse: Default::default(),
         required_source_files: Some(GrowableBitSet::with_capacity(source_map_files.len())),
         is_proc_macro: tcx.sess.crate_types().contains(&CrateType::ProcMacro),
+        serialized_ctxts: Some(Default::default()),
+        latest_ctxts: Some(Default::default()),
     };
     drop(source_map_files);
 
diff --git a/src/librustc_metadata/rmeta/mod.rs b/src/librustc_metadata/rmeta/mod.rs
index e616e8cf00a..55ef66f1939 100644
--- a/src/librustc_metadata/rmeta/mod.rs
+++ b/src/librustc_metadata/rmeta/mod.rs
@@ -20,7 +20,7 @@ use rustc_session::config::SymbolManglingVersion;
 use rustc_session::CrateDisambiguator;
 use rustc_span::edition::Edition;
 use rustc_span::symbol::{Ident, Symbol};
-use rustc_span::{self, Span};
+use rustc_span::{self, ExpnData, ExpnId, Span};
 use rustc_target::spec::{PanicStrategy, TargetTriple};
 
 use std::marker::PhantomData;
@@ -28,6 +28,7 @@ use std::num::NonZeroUsize;
 
 pub use decoder::{provide, provide_extern};
 crate use decoder::{CrateMetadata, CrateNumMap, MetadataBlob};
+use rustc_span::hygiene::SyntaxContextData;
 
 mod decoder;
 mod encoder;
@@ -168,6 +169,9 @@ macro_rules! Lazy {
     ($T:ty) => {Lazy<$T, ()>};
 }
 
+type SyntaxContextTable = Lazy<Table<u32, Lazy<SyntaxContextData>>>;
+type ExpnDataTable = Lazy<Table<u32, Lazy<ExpnData>>>;
+
 #[derive(RustcEncodable, RustcDecodable)]
 crate struct CrateRoot<'tcx> {
     name: Symbol,
@@ -202,6 +206,10 @@ crate struct CrateRoot<'tcx> {
     proc_macro_data: Option<Lazy<[DefIndex]>>,
 
     exported_symbols: Lazy!([(ExportedSymbol<'tcx>, SymbolExportLevel)]),
+
+    syntax_contexts: SyntaxContextTable,
+    expn_data: ExpnDataTable,
+
     source_map: Lazy<[rustc_span::SourceFile]>,
 
     compiler_builtins: bool,
@@ -322,6 +330,7 @@ struct RenderedConst(String);
 #[derive(RustcEncodable, RustcDecodable)]
 struct ModData {
     reexports: Lazy<[Export<hir::HirId>]>,
+    expansion: ExpnId,
 }
 
 #[derive(RustcEncodable, RustcDecodable)]
diff --git a/src/librustc_metadata/rmeta/table.rs b/src/librustc_metadata/rmeta/table.rs
index bacb5a345fc..e1d0a0dbf2f 100644
--- a/src/librustc_metadata/rmeta/table.rs
+++ b/src/librustc_metadata/rmeta/table.rs
@@ -155,7 +155,7 @@ impl<I: Idx, T> TableBuilder<I, T>
 where
     Option<T>: FixedSizeEncoding,
 {
-    pub(super) fn set(&mut self, i: I, value: T) {
+    pub(crate) fn set(&mut self, i: I, value: T) {
         // FIXME(eddyb) investigate more compact encodings for sparse tables.
         // On the PR @michaelwoerister mentioned:
         // > Space requirements could perhaps be optimized by using the HAMT `popcnt`
@@ -170,7 +170,7 @@ where
         Some(value).write_to_bytes_at(&mut self.bytes, i);
     }
 
-    pub(super) fn encode(&self, buf: &mut Encoder) -> Lazy<Table<I, T>> {
+    pub(crate) fn encode(&self, buf: &mut Encoder) -> Lazy<Table<I, T>> {
         let pos = buf.position();
         buf.emit_raw_bytes(&self.bytes);
         Lazy::from_position_and_meta(NonZeroUsize::new(pos as usize).unwrap(), self.bytes.len())
diff --git a/src/librustc_middle/ich/hcx.rs b/src/librustc_middle/ich/hcx.rs
index f5b0b73c49d..19a7d2ec221 100644
--- a/src/librustc_middle/ich/hcx.rs
+++ b/src/librustc_middle/ich/hcx.rs
@@ -14,6 +14,7 @@ use rustc_span::source_map::SourceMap;
 use rustc_span::symbol::Symbol;
 use rustc_span::{BytePos, CachingSourceMapView, SourceFile};
 
+use rustc_span::def_id::{CrateNum, CRATE_DEF_INDEX};
 use smallvec::SmallVec;
 use std::cmp::Ord;
 
@@ -230,6 +231,12 @@ impl<'a> rustc_span::HashStableContext for StableHashingContext<'a> {
     }
 
     #[inline]
+    fn hash_crate_num(&mut self, cnum: CrateNum, hasher: &mut StableHasher) {
+        let hcx = self;
+        hcx.def_path_hash(DefId { krate: cnum, index: CRATE_DEF_INDEX }).hash_stable(hcx, hasher);
+    }
+
+    #[inline]
     fn hash_def_id(&mut self, def_id: DefId, hasher: &mut StableHasher) {
         let hcx = self;
         hcx.def_path_hash(def_id).hash_stable(hcx, hasher);
diff --git a/src/librustc_middle/ich/impls_hir.rs b/src/librustc_middle/ich/impls_hir.rs
index 78b9167ddd9..c2d177b69b6 100644
--- a/src/librustc_middle/ich/impls_hir.rs
+++ b/src/librustc_middle/ich/impls_hir.rs
@@ -147,13 +147,6 @@ impl<'a> ToStableHashKey<StableHashingContext<'a>> for LocalDefId {
     }
 }
 
-impl<'a> HashStable<StableHashingContext<'a>> for CrateNum {
-    #[inline]
-    fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
-        hcx.def_path_hash(DefId { krate: *self, index: CRATE_DEF_INDEX }).hash_stable(hcx, hasher);
-    }
-}
-
 impl<'a> ToStableHashKey<StableHashingContext<'a>> for CrateNum {
     type KeyType = DefPathHash;
 
diff --git a/src/librustc_middle/lint.rs b/src/librustc_middle/lint.rs
index 3f0939239e8..25e5379881e 100644
--- a/src/librustc_middle/lint.rs
+++ b/src/librustc_middle/lint.rs
@@ -346,6 +346,6 @@ pub fn in_external_macro(sess: &Session, span: Span) -> bool {
             // Dummy span for the `def_site` means it's an external macro.
             expn_data.def_site.is_dummy() || sess.source_map().is_imported(expn_data.def_site)
         }
-        ExpnKind::Macro(..) => true, // definitely a plugin
+        ExpnKind::Macro { .. } => true, // definitely a plugin
     }
 }
diff --git a/src/librustc_middle/ty/query/on_disk_cache.rs b/src/librustc_middle/ty/query/on_disk_cache.rs
index 1ba305e63fb..ed330321bdb 100644
--- a/src/librustc_middle/ty/query/on_disk_cache.rs
+++ b/src/librustc_middle/ty/query/on_disk_cache.rs
@@ -17,22 +17,24 @@ use rustc_serialize::{
     UseSpecializedDecodable, UseSpecializedEncodable,
 };
 use rustc_session::{CrateDisambiguator, Session};
-use rustc_span::hygiene::{ExpnId, SyntaxContext};
+use rustc_span::hygiene::{
+    ExpnDataDecodeMode, ExpnDataEncodeMode, ExpnId, HygieneContext, SyntaxContext,
+    SyntaxContextData,
+};
 use rustc_span::source_map::{SourceMap, StableSourceFileId};
 use rustc_span::symbol::Ident;
 use rustc_span::CachingSourceMapView;
-use rustc_span::{BytePos, SourceFile, Span, DUMMY_SP};
+use rustc_span::{BytePos, ExpnData, SourceFile, Span, DUMMY_SP};
 use std::mem;
 
 const TAG_FILE_FOOTER: u128 = 0xC0FFEE_C0FFEE_C0FFEE_C0FFEE_C0FFEE;
 
-const TAG_NO_EXPN_DATA: u8 = 0;
-const TAG_EXPN_DATA_SHORTHAND: u8 = 1;
-const TAG_EXPN_DATA_INLINE: u8 = 2;
-
 const TAG_VALID_SPAN: u8 = 0;
 const TAG_INVALID_SPAN: u8 = 1;
 
+const TAG_SYNTAX_CONTEXT: u8 = 0;
+const TAG_EXPN_DATA: u8 = 1;
+
 /// Provides an interface to incremental compilation data cached from the
 /// previous compilation session. This data will eventually include the results
 /// of a few selected queries (like `typeck` and `mir_optimized`) and
@@ -53,7 +55,6 @@ pub struct OnDiskCache<'sess> {
 
     // Caches that are populated lazily during decoding.
     file_index_to_file: Lock<FxHashMap<SourceFileIndex, Lrc<SourceFile>>>,
-    synthetic_syntax_contexts: Lock<FxHashMap<AbsoluteBytePos, SyntaxContext>>,
 
     // A map from dep-node to the position of the cached query result in
     // `serialized_data`.
@@ -64,9 +65,28 @@ pub struct OnDiskCache<'sess> {
     prev_diagnostics_index: FxHashMap<SerializedDepNodeIndex, AbsoluteBytePos>,
 
     alloc_decoding_state: AllocDecodingState,
+
+    // A map from syntax context ids to the position of their associated
+    // `SyntaxContextData`. We use a `u32` instead of a `SyntaxContext`
+    // to represent the fact that we are storing *encoded* ids. When we decode
+    // a `SyntaxContext`, a new id will be allocated from the global `HygieneData`,
+    // which will almost certainly be different than the serialized id.
+    syntax_contexts: FxHashMap<u32, AbsoluteBytePos>,
+    // A map from the `DefPathHash` of an `ExpnId` to the position
+    // of their associated `ExpnData`. Ideally, we would store a `DefId`,
+    // but we need to decode this before we've constructed a `TyCtxt` (which
+    // makes it difficult to decode a `DefId`).
+
+    // Note that these `DefPathHashes` correspond to both local and foreign
+    // `ExpnData` (e.g `ExpnData.krate` may not be `LOCAL_CRATE`). Alternatively,
+    // we could look up the `ExpnData` from the metadata of foreign crates,
+    // but it seemed easier to have `OnDiskCache` be independent of the `CStore`.
+    expn_data: FxHashMap<u32, AbsoluteBytePos>,
+    // Additional information used when decoding hygiene data.
+    hygiene_context: HygieneContext,
 }
 
-// This type is used only for (de-)serialization.
+// This type is used only for serialization and deserialization.
 #[derive(RustcEncodable, RustcDecodable)]
 struct Footer {
     file_index_to_stable_id: FxHashMap<SourceFileIndex, StableSourceFileId>,
@@ -75,6 +95,10 @@ struct Footer {
     diagnostics_index: EncodedQueryResultIndex,
     // The location of all allocations.
     interpret_alloc_index: Vec<u32>,
+    // See `OnDiskCache.syntax_contexts`
+    syntax_contexts: FxHashMap<u32, AbsoluteBytePos>,
+    // See `OnDiskCache.expn_data`
+    expn_data: FxHashMap<u32, AbsoluteBytePos>,
 }
 
 type EncodedQueryResultIndex = Vec<(SerializedDepNodeIndex, AbsoluteBytePos)>;
@@ -116,6 +140,7 @@ impl<'sess> OnDiskCache<'sess> {
 
             // Decode the file footer, which contains all the lookup tables, etc.
             decoder.set_position(footer_pos);
+
             decode_tagged(&mut decoder, TAG_FILE_FOOTER)
                 .expect("error while trying to decode footer position")
         };
@@ -130,8 +155,10 @@ impl<'sess> OnDiskCache<'sess> {
             current_diagnostics: Default::default(),
             query_result_index: footer.query_result_index.into_iter().collect(),
             prev_diagnostics_index: footer.diagnostics_index.into_iter().collect(),
-            synthetic_syntax_contexts: Default::default(),
             alloc_decoding_state: AllocDecodingState::new(footer.interpret_alloc_index),
+            syntax_contexts: footer.syntax_contexts,
+            expn_data: footer.expn_data,
+            hygiene_context: HygieneContext::new(),
         }
     }
 
@@ -146,8 +173,10 @@ impl<'sess> OnDiskCache<'sess> {
             current_diagnostics: Default::default(),
             query_result_index: Default::default(),
             prev_diagnostics_index: Default::default(),
-            synthetic_syntax_contexts: Default::default(),
             alloc_decoding_state: AllocDecodingState::new(Vec::new()),
+            syntax_contexts: FxHashMap::default(),
+            expn_data: FxHashMap::default(),
+            hygiene_context: HygieneContext::new(),
         }
     }
 
@@ -180,7 +209,6 @@ impl<'sess> OnDiskCache<'sess> {
                 encoder,
                 type_shorthands: Default::default(),
                 predicate_shorthands: Default::default(),
-                expn_data_shorthands: Default::default(),
                 interpret_allocs: Default::default(),
                 interpret_allocs_inverse: Vec::new(),
                 source_map: CachingSourceMapView::new(tcx.sess.source_map()),
@@ -264,7 +292,32 @@ impl<'sess> OnDiskCache<'sess> {
                 })
                 .collect();
 
-            // Encode the file footer.
+            let mut syntax_contexts = FxHashMap::default();
+            let mut expn_data = FxHashMap::default();
+
+            // Encode all hygiene data (`SyntaxContextData` and `ExpnData`) from the current
+            // session.
+            // FIXME: Investigate tracking which `SyntaxContext`s and `ExpnId`s we actually
+            // need, to avoid serializing data that will never be used. This will require
+            // tracking which `SyntaxContext`s/`ExpnId`s are actually (transitively) referenced
+            // from any of the `Span`s that we serialize.
+
+            rustc_span::hygiene::for_all_data(|(index, _ctxt, data)| {
+                let pos = AbsoluteBytePos::new(encoder.position());
+                encoder.encode_tagged(TAG_SYNTAX_CONTEXT, data)?;
+                syntax_contexts.insert(index, pos);
+                Ok(())
+            })?;
+
+            rustc_span::hygiene::for_all_expn_data(|index, data| {
+                let pos = AbsoluteBytePos::new(encoder.position());
+                encoder.encode_tagged(TAG_EXPN_DATA, data)?;
+                //let hash = tcx.def_path_hash(data.def_id.unwrap());
+                expn_data.insert(index, pos);
+                Ok(())
+            })?;
+
+            // `Encode the file footer.
             let footer_pos = encoder.position() as u64;
             encoder.encode_tagged(
                 TAG_FILE_FOOTER,
@@ -274,6 +327,8 @@ impl<'sess> OnDiskCache<'sess> {
                     query_result_index,
                     diagnostics_index,
                     interpret_alloc_index,
+                    syntax_contexts,
+                    expn_data,
                 },
             )?;
 
@@ -367,6 +422,21 @@ impl<'sess> OnDiskCache<'sess> {
     {
         let pos = index.get(&dep_node_index).cloned()?;
 
+        self.with_decoder(tcx, pos, |decoder| match decode_tagged(decoder, dep_node_index) {
+            Ok(v) => Some(v),
+            Err(e) => bug!("could not decode cached {}: {}", debug_tag, e),
+        })
+    }
+
+    fn with_decoder<'tcx, T, F: FnOnce(&mut CacheDecoder<'sess, 'tcx>) -> T>(
+        &'sess self,
+        tcx: TyCtxt<'tcx>,
+        pos: AbsoluteBytePos,
+        f: F,
+    ) -> T
+    where
+        T: Decodable,
+    {
         let cnum_map =
             self.cnum_map.get_or_init(|| Self::compute_cnum_map(tcx, &self.prev_cnums[..]));
 
@@ -375,16 +445,14 @@ impl<'sess> OnDiskCache<'sess> {
             opaque: opaque::Decoder::new(&self.serialized_data[..], pos.to_usize()),
             source_map: self.source_map,
             cnum_map,
-            synthetic_syntax_contexts: &self.synthetic_syntax_contexts,
             file_index_to_file: &self.file_index_to_file,
             file_index_to_stable_id: &self.file_index_to_stable_id,
             alloc_decoding_session: self.alloc_decoding_state.new_decoding_session(),
+            syntax_contexts: &self.syntax_contexts,
+            expn_data: &self.expn_data,
+            hygiene_context: &self.hygiene_context,
         };
-
-        match decode_tagged(&mut decoder, dep_node_index) {
-            Ok(v) => Some(v),
-            Err(e) => bug!("could not decode cached {}: {}", debug_tag, e),
-        }
+        f(&mut decoder)
     }
 
     // This function builds mapping from previous-session-`CrateNum` to
@@ -430,10 +498,12 @@ struct CacheDecoder<'a, 'tcx> {
     opaque: opaque::Decoder<'a>,
     source_map: &'a SourceMap,
     cnum_map: &'a IndexVec<CrateNum, Option<CrateNum>>,
-    synthetic_syntax_contexts: &'a Lock<FxHashMap<AbsoluteBytePos, SyntaxContext>>,
     file_index_to_file: &'a Lock<FxHashMap<SourceFileIndex, Lrc<SourceFile>>>,
     file_index_to_stable_id: &'a FxHashMap<SourceFileIndex, StableSourceFileId>,
     alloc_decoding_session: AllocDecodingSession<'a>,
+    syntax_contexts: &'a FxHashMap<u32, AbsoluteBytePos>,
+    expn_data: &'a FxHashMap<u32, AbsoluteBytePos>,
+    hygiene_context: &'a HygieneContext,
 }
 
 impl<'a, 'tcx> CacheDecoder<'a, 'tcx> {
@@ -577,6 +647,43 @@ impl<'a, 'tcx> TyDecoder<'tcx> for CacheDecoder<'a, 'tcx> {
 
 implement_ty_decoder!(CacheDecoder<'a, 'tcx>);
 
+impl<'a, 'tcx> SpecializedDecoder<SyntaxContext> for CacheDecoder<'a, 'tcx> {
+    fn specialized_decode(&mut self) -> Result<SyntaxContext, Self::Error> {
+        let syntax_contexts = self.syntax_contexts;
+        rustc_span::hygiene::decode_syntax_context(self, self.hygiene_context, |this, id| {
+            // This closure is invoked if we haven't already decoded the data for the `SyntaxContext` we are deserializing.
+            // We look up the position of the associated `SyntaxData` and decode it.
+            let pos = syntax_contexts.get(&id).unwrap();
+            this.with_position(pos.to_usize(), |decoder| {
+                let data: SyntaxContextData = decode_tagged(decoder, TAG_SYNTAX_CONTEXT)?;
+                Ok(data)
+            })
+        })
+    }
+}
+
+impl<'a, 'tcx> SpecializedDecoder<ExpnId> for CacheDecoder<'a, 'tcx> {
+    fn specialized_decode(&mut self) -> Result<ExpnId, Self::Error> {
+        let expn_data = self.expn_data;
+        rustc_span::hygiene::decode_expn_id(
+            self,
+            ExpnDataDecodeMode::incr_comp(self.hygiene_context),
+            |this, index| {
+                // This closure is invoked if we haven't already decoded the data for the `ExpnId` we are deserializing.
+                // We look up the position of the associated `ExpnData` and decode it.
+                let pos = expn_data
+                    .get(&index)
+                    .unwrap_or_else(|| panic!("Bad index {:?} (map {:?})", index, expn_data));
+
+                this.with_position(pos.to_usize(), |decoder| {
+                    let data: ExpnData = decode_tagged(decoder, TAG_EXPN_DATA)?;
+                    Ok(data)
+                })
+            },
+        )
+    }
+}
+
 impl<'a, 'tcx> SpecializedDecoder<interpret::AllocId> for CacheDecoder<'a, 'tcx> {
     fn specialized_decode(&mut self) -> Result<interpret::AllocId, Self::Error> {
         let alloc_decoding_session = self.alloc_decoding_session;
@@ -598,48 +705,13 @@ impl<'a, 'tcx> SpecializedDecoder<Span> for CacheDecoder<'a, 'tcx> {
         let line_lo = usize::decode(self)?;
         let col_lo = BytePos::decode(self)?;
         let len = BytePos::decode(self)?;
+        let ctxt = SyntaxContext::decode(self)?;
 
         let file_lo = self.file_index_to_file(file_lo_index);
         let lo = file_lo.lines[line_lo - 1] + col_lo;
         let hi = lo + len;
 
-        let expn_data_tag = u8::decode(self)?;
-
-        // FIXME(mw): This method does not restore `ExpnData::parent` or
-        // `SyntaxContextData::prev_ctxt` or `SyntaxContextData::opaque`. These things
-        // don't seem to be used after HIR lowering, so everything should be fine
-        // until we want incremental compilation to serialize Spans that we need
-        // full hygiene information for.
-        let location = || Span::with_root_ctxt(lo, hi);
-        let recover_from_expn_data = |this: &Self, expn_data, transparency, pos| {
-            let span = location().fresh_expansion_with_transparency(expn_data, transparency);
-            this.synthetic_syntax_contexts.borrow_mut().insert(pos, span.ctxt());
-            span
-        };
-        Ok(match expn_data_tag {
-            TAG_NO_EXPN_DATA => location(),
-            TAG_EXPN_DATA_INLINE => {
-                let (expn_data, transparency) = Decodable::decode(self)?;
-                recover_from_expn_data(
-                    self,
-                    expn_data,
-                    transparency,
-                    AbsoluteBytePos::new(self.opaque.position()),
-                )
-            }
-            TAG_EXPN_DATA_SHORTHAND => {
-                let pos = AbsoluteBytePos::decode(self)?;
-                let cached_ctxt = self.synthetic_syntax_contexts.borrow().get(&pos).cloned();
-                if let Some(ctxt) = cached_ctxt {
-                    Span::new(lo, hi, ctxt)
-                } else {
-                    let (expn_data, transparency) =
-                        self.with_position(pos.to_usize(), |this| Decodable::decode(this))?;
-                    recover_from_expn_data(self, expn_data, transparency, pos)
-                }
-            }
-            _ => unreachable!(),
-        })
+        Ok(Span::new(lo, hi, ctxt))
     }
 }
 
@@ -695,7 +767,6 @@ struct CacheEncoder<'a, 'tcx, E: ty_codec::TyEncoder> {
     encoder: &'a mut E,
     type_shorthands: FxHashMap<Ty<'tcx>, usize>,
     predicate_shorthands: FxHashMap<ty::Predicate<'tcx>, usize>,
-    expn_data_shorthands: FxHashMap<ExpnId, AbsoluteBytePos>,
     interpret_allocs: FxHashMap<interpret::AllocId, usize>,
     interpret_allocs_inverse: Vec<interpret::AllocId>,
     source_map: CachingSourceMapView<'tcx>,
@@ -750,6 +821,24 @@ where
     }
 }
 
+impl<'a, 'tcx, E> SpecializedEncoder<SyntaxContext> for CacheEncoder<'a, 'tcx, E>
+where
+    E: 'a + TyEncoder,
+{
+    fn specialized_encode(&mut self, ctxt: &SyntaxContext) -> Result<(), Self::Error> {
+        rustc_span::hygiene::raw_encode_syntax_context(*ctxt, self)
+    }
+}
+
+impl<'a, 'tcx, E> SpecializedEncoder<ExpnId> for CacheEncoder<'a, 'tcx, E>
+where
+    E: 'a + TyEncoder,
+{
+    fn specialized_encode(&mut self, expn: &ExpnId) -> Result<(), Self::Error> {
+        rustc_span::hygiene::raw_encode_expn_id(*expn, ExpnDataEncodeMode::IncrComp, self)
+    }
+}
+
 impl<'a, 'tcx, E> SpecializedEncoder<Span> for CacheEncoder<'a, 'tcx, E>
 where
     E: 'a + TyEncoder,
@@ -779,21 +868,8 @@ where
         line_lo.encode(self)?;
         col_lo.encode(self)?;
         len.encode(self)?;
-
-        if span_data.ctxt == SyntaxContext::root() {
-            TAG_NO_EXPN_DATA.encode(self)
-        } else {
-            let (expn_id, transparency, expn_data) = span_data.ctxt.outer_mark_with_data();
-            if let Some(pos) = self.expn_data_shorthands.get(&expn_id).cloned() {
-                TAG_EXPN_DATA_SHORTHAND.encode(self)?;
-                pos.encode(self)
-            } else {
-                TAG_EXPN_DATA_INLINE.encode(self)?;
-                let pos = AbsoluteBytePos::new(self.position());
-                self.expn_data_shorthands.insert(expn_id, pos);
-                (expn_data, transparency).encode(self)
-            }
-        }
+        span_data.ctxt.encode(self)?;
+        Ok(())
     }
 }
 
diff --git a/src/librustc_resolve/build_reduced_graph.rs b/src/librustc_resolve/build_reduced_graph.rs
index 45253fc8782..737fd138120 100644
--- a/src/librustc_resolve/build_reduced_graph.rs
+++ b/src/librustc_resolve/build_reduced_graph.rs
@@ -35,7 +35,7 @@ use rustc_middle::ty;
 use rustc_span::hygiene::{ExpnId, MacroKind};
 use rustc_span::source_map::{respan, Spanned};
 use rustc_span::symbol::{kw, sym, Ident, Symbol};
-use rustc_span::{Span, DUMMY_SP};
+use rustc_span::Span;
 
 use log::debug;
 use std::cell::Cell;
@@ -130,8 +130,8 @@ impl<'a> Resolver<'a> {
             parent,
             kind,
             def_id,
-            ExpnId::root(),
-            DUMMY_SP,
+            self.cstore().module_expansion_untracked(def_id, &self.session),
+            self.cstore().get_span_untracked(def_id, &self.session),
         ));
         self.extern_module_map.insert(def_id, module);
         module
@@ -888,7 +888,7 @@ impl<'a, 'b> BuildReducedGraphVisitor<'a, 'b> {
     fn build_reduced_graph_for_external_crate_res(&mut self, child: Export<NodeId>) {
         let parent = self.parent_scope.module;
         let Export { ident, res, vis, span } = child;
-        let expansion = ExpnId::root(); // FIXME(jseyfried) intercrate hygiene
+        let expansion = self.parent_scope.expansion;
         // Record primary definitions.
         match res {
             Res::Def(kind @ (DefKind::Mod | DefKind::Enum | DefKind::Trait), def_id) => {
diff --git a/src/librustc_resolve/lib.rs b/src/librustc_resolve/lib.rs
index da39f79efcd..dfc50a30c12 100644
--- a/src/librustc_resolve/lib.rs
+++ b/src/librustc_resolve/lib.rs
@@ -434,7 +434,7 @@ impl ModuleKind {
 ///
 /// Multiple bindings in the same module can have the same key (in a valid
 /// program) if all but one of them come from glob imports.
-#[derive(Copy, Clone, PartialEq, Eq, Hash)]
+#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
 struct BindingKey {
     /// The identifier for the binding, aways the `normalize_to_macros_2_0` version of the
     /// identifier.
@@ -1988,6 +1988,7 @@ impl<'a> Resolver<'a> {
     }
 
     fn resolve_crate_root(&mut self, ident: Ident) -> Module<'a> {
+        debug!("resolve_crate_root({:?})", ident);
         let mut ctxt = ident.span.ctxt();
         let mark = if ident.name == kw::DollarCrate {
             // When resolving `$crate` from a `macro_rules!` invoked in a `macro`,
@@ -1997,6 +1998,10 @@ impl<'a> Resolver<'a> {
             // definitions actually produced by `macro` and `macro` definitions produced by
             // `macro_rules!`, but at least such configurations are not stable yet.
             ctxt = ctxt.normalize_to_macro_rules();
+            debug!(
+                "resolve_crate_root: marks={:?}",
+                ctxt.marks().into_iter().map(|(i, t)| (i.expn_data(), t)).collect::<Vec<_>>()
+            );
             let mut iter = ctxt.marks().into_iter().rev().peekable();
             let mut result = None;
             // Find the last opaque mark from the end if it exists.
@@ -2008,6 +2013,11 @@ impl<'a> Resolver<'a> {
                     break;
                 }
             }
+            debug!(
+                "resolve_crate_root: found opaque mark {:?} {:?}",
+                result,
+                result.map(|r| r.expn_data())
+            );
             // Then find the last semi-transparent mark from the end if it exists.
             for (mark, transparency) in iter {
                 if transparency == Transparency::SemiTransparent {
@@ -2016,16 +2026,36 @@ impl<'a> Resolver<'a> {
                     break;
                 }
             }
+            debug!(
+                "resolve_crate_root: found semi-transparent mark {:?} {:?}",
+                result,
+                result.map(|r| r.expn_data())
+            );
             result
         } else {
+            debug!("resolve_crate_root: not DollarCrate");
             ctxt = ctxt.normalize_to_macros_2_0();
             ctxt.adjust(ExpnId::root())
         };
         let module = match mark {
             Some(def) => self.macro_def_scope(def),
-            None => return self.graph_root,
+            None => {
+                debug!(
+                    "resolve_crate_root({:?}): found no mark (ident.span = {:?})",
+                    ident, ident.span
+                );
+                return self.graph_root;
+            }
         };
-        self.get_module(DefId { index: CRATE_DEF_INDEX, ..module.normal_ancestor_id })
+        let module = self.get_module(DefId { index: CRATE_DEF_INDEX, ..module.normal_ancestor_id });
+        debug!(
+            "resolve_crate_root({:?}): got module {:?} ({:?}) (ident.span = {:?})",
+            ident,
+            module,
+            module.kind.name(),
+            ident.span
+        );
+        module
     }
 
     fn resolve_self(&mut self, ctxt: &mut SyntaxContext, module: Module<'a>) -> Module<'a> {
diff --git a/src/librustc_save_analysis/lib.rs b/src/librustc_save_analysis/lib.rs
index 22526fc61e6..0751dbb027a 100644
--- a/src/librustc_save_analysis/lib.rs
+++ b/src/librustc_save_analysis/lib.rs
@@ -789,7 +789,7 @@ impl<'tcx> SaveContext<'tcx> {
         let callee = span.source_callee()?;
 
         let mac_name = match callee.kind {
-            ExpnKind::Macro(mac_kind, name) => match mac_kind {
+            ExpnKind::Macro(kind, name) => match kind {
                 MacroKind::Bang => name,
 
                 // Ignore attribute macros, their spans are usually mangled
diff --git a/src/librustc_span/def_id.rs b/src/librustc_span/def_id.rs
index 0a70be1f152..a874f81868f 100644
--- a/src/librustc_span/def_id.rs
+++ b/src/librustc_span/def_id.rs
@@ -247,3 +247,9 @@ impl<CTX: HashStableContext> HashStable<CTX> for DefId {
         hcx.hash_def_id(*self, hasher)
     }
 }
+
+impl<CTX: HashStableContext> HashStable<CTX> for CrateNum {
+    fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) {
+        hcx.hash_crate_num(*self, hasher)
+    }
+}
diff --git a/src/librustc_span/hygiene.rs b/src/librustc_span/hygiene.rs
index 7249894ba28..c5ba42c5728 100644
--- a/src/librustc_span/hygiene.rs
+++ b/src/librustc_span/hygiene.rs
@@ -24,24 +24,27 @@
 // because getting it wrong can lead to nested `HygieneData::with` calls that
 // trigger runtime aborts. (Fortunately these are obvious and easy to fix.)
 
-use crate::def_id::{DefId, CRATE_DEF_INDEX};
 use crate::edition::Edition;
 use crate::symbol::{kw, sym, Symbol};
 use crate::SESSION_GLOBALS;
 use crate::{Span, DUMMY_SP};
 
+use crate::def_id::{CrateNum, DefId, CRATE_DEF_INDEX, LOCAL_CRATE};
+use log::*;
 use rustc_data_structures::fx::FxHashMap;
-use rustc_data_structures::sync::Lrc;
+use rustc_data_structures::sync::{Lock, Lrc};
 use rustc_macros::HashStable_Generic;
-use rustc_serialize::{Decodable, Decoder, Encodable, Encoder};
+use rustc_serialize::{
+    Decodable, Decoder, Encodable, Encoder, UseSpecializedDecodable, UseSpecializedEncodable,
+};
 use std::fmt;
 
 /// A `SyntaxContext` represents a chain of pairs `(ExpnId, Transparency)` named "marks".
 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub struct SyntaxContext(u32);
 
-#[derive(Debug)]
-struct SyntaxContextData {
+#[derive(Debug, RustcEncodable, RustcDecodable, Clone)]
+pub struct SyntaxContextData {
     outer_expn: ExpnId,
     outer_transparency: Transparency,
     parent: SyntaxContext,
@@ -77,6 +80,8 @@ pub enum Transparency {
     Opaque,
 }
 
+pub(crate) const NUM_TRANSPARENCIES: usize = 3;
+
 impl ExpnId {
     pub fn fresh(expn_data: Option<ExpnData>) -> Self {
         HygieneData::with(|data| data.fresh_expn(expn_data))
@@ -104,10 +109,11 @@ impl ExpnId {
     }
 
     #[inline]
-    pub fn set_expn_data(self, expn_data: ExpnData) {
+    pub fn set_expn_data(self, mut expn_data: ExpnData) {
         HygieneData::with(|data| {
             let old_expn_data = &mut data.expn_data[self.0 as usize];
             assert!(old_expn_data.is_none(), "expansion data is reset for an expansion ID");
+            expn_data.orig_id.replace(self.as_u32()).expect_none("orig_id should be None");
             *old_expn_data = Some(expn_data);
         })
     }
@@ -143,7 +149,7 @@ impl ExpnId {
 }
 
 #[derive(Debug)]
-crate struct HygieneData {
+pub struct HygieneData {
     /// Each expansion should have an associated expansion data, but sometimes there's a delay
     /// between creation of an expansion ID and obtaining its data (e.g. macros are collected
     /// first and then resolved later), so we use an `Option` here.
@@ -154,13 +160,16 @@ crate struct HygieneData {
 
 impl HygieneData {
     crate fn new(edition: Edition) -> Self {
+        let mut root_data = ExpnData::default(
+            ExpnKind::Root,
+            DUMMY_SP,
+            edition,
+            Some(DefId::local(CRATE_DEF_INDEX)),
+        );
+        root_data.orig_id = Some(0);
+
         HygieneData {
-            expn_data: vec![Some(ExpnData::default(
-                ExpnKind::Root,
-                DUMMY_SP,
-                edition,
-                Some(DefId::local(CRATE_DEF_INDEX)),
-            ))],
+            expn_data: vec![Some(root_data)],
             syntax_context_data: vec![SyntaxContextData {
                 outer_expn: ExpnId::root(),
                 outer_transparency: Transparency::Opaque,
@@ -173,13 +182,17 @@ impl HygieneData {
         }
     }
 
-    fn with<T, F: FnOnce(&mut HygieneData) -> T>(f: F) -> T {
+    pub fn with<T, F: FnOnce(&mut HygieneData) -> T>(f: F) -> T {
         SESSION_GLOBALS.with(|session_globals| f(&mut *session_globals.hygiene_data.borrow_mut()))
     }
 
-    fn fresh_expn(&mut self, expn_data: Option<ExpnData>) -> ExpnId {
+    fn fresh_expn(&mut self, mut expn_data: Option<ExpnData>) -> ExpnId {
+        let raw_id = self.expn_data.len() as u32;
+        if let Some(data) = expn_data.as_mut() {
+            data.orig_id.replace(raw_id).expect_none("orig_id should be None");
+        }
         self.expn_data.push(expn_data);
-        ExpnId(self.expn_data.len() as u32 - 1)
+        ExpnId(raw_id)
     }
 
     fn expn_data(&self, expn_id: ExpnId) -> &ExpnData {
@@ -226,6 +239,7 @@ impl HygieneData {
     fn marks(&self, mut ctxt: SyntaxContext) -> Vec<(ExpnId, Transparency)> {
         let mut marks = Vec::new();
         while ctxt != SyntaxContext::root() {
+            debug!("marks: getting parent of {:?}", ctxt);
             marks.push(self.outer_mark(ctxt));
             ctxt = self.parent_ctxt(ctxt);
         }
@@ -234,8 +248,14 @@ impl HygieneData {
     }
 
     fn walk_chain(&self, mut span: Span, to: SyntaxContext) -> Span {
+        debug!("walk_chain({:?}, {:?})", span, to);
+        debug!("walk_chain: span ctxt = {:?}", span.ctxt());
         while span.from_expansion() && span.ctxt() != to {
-            span = self.expn_data(self.outer_expn(span.ctxt())).call_site;
+            let outer_expn = self.outer_expn(span.ctxt());
+            debug!("walk_chain({:?}): outer_expn={:?}", span, outer_expn);
+            let expn_data = self.expn_data(outer_expn);
+            debug!("walk_chain({:?}): expn_data={:?}", span, expn_data);
+            span = expn_data.call_site;
         }
         span
     }
@@ -682,6 +702,16 @@ pub struct ExpnData {
     /// The `DefId` of the macro being invoked,
     /// if this `ExpnData` corresponds to a macro invocation
     pub macro_def_id: Option<DefId>,
+    /// The crate that originally created this `ExpnData. During
+    /// metadata serialization, we only encode `ExpnData`s that were
+    /// created locally - when our serialized metadata is decoded,
+    /// foreign `ExpnId`s will have their `ExpnData` looked up
+    /// from the crate specified by `Crate
+    pub krate: CrateNum,
+    /// The raw that this `ExpnData` had in its original crate.
+    /// An `ExpnData` can be created before being assigned an `ExpnId`,
+    /// so this might be `None` until `set_expn_data` is called
+    pub orig_id: Option<u32>,
 }
 
 impl ExpnData {
@@ -702,6 +732,8 @@ impl ExpnData {
             local_inner_macros: false,
             edition,
             macro_def_id,
+            krate: LOCAL_CRATE,
+            orig_id: None,
         }
     }
 
@@ -789,7 +821,7 @@ impl MacroKind {
 }
 
 /// The kind of AST transform.
-#[derive(Clone, Copy, PartialEq, Debug, RustcEncodable, RustcDecodable, HashStable_Generic)]
+#[derive(Clone, Copy, Debug, PartialEq, RustcEncodable, RustcDecodable, HashStable_Generic)]
 pub enum AstPass {
     StdImports,
     TestHarness,
@@ -847,14 +879,234 @@ impl DesugaringKind {
     }
 }
 
-impl Encodable for ExpnId {
-    fn encode<E: Encoder>(&self, _: &mut E) -> Result<(), E::Error> {
-        Ok(()) // FIXME(jseyfried) intercrate hygiene
+impl UseSpecializedEncodable for ExpnId {}
+impl UseSpecializedDecodable for ExpnId {}
+
+/// Additional information used to assist in decoding hygiene data
+pub struct HygieneContext {
+    // Maps serialized `SyntaxContext` ids to a `SyntaxContext` in the current
+    // global `HygieneData`. When we deserialize a `SyntaxContext`, we need to create
+    // a new id in the global `HygieneData`. This map tracks the ID we end up picking,
+    // so that multiple occurences of the same serialized id are decoded to the same
+    // `SyntaxContext`
+    remapped_ctxts: Lock<Vec<Option<SyntaxContext>>>,
+    // The same as `remapepd_ctxts`, but for `ExpnId`s
+    remapped_expns: Lock<Vec<Option<ExpnId>>>,
+}
+
+impl HygieneContext {
+    pub fn new() -> HygieneContext {
+        HygieneContext {
+            remapped_ctxts: Lock::new(Vec::new()),
+            remapped_expns: Lock::new(Vec::new()),
+        }
     }
 }
 
-impl Decodable for ExpnId {
-    fn decode<D: Decoder>(_: &mut D) -> Result<Self, D::Error> {
-        Ok(ExpnId::root()) // FIXME(jseyfried) intercrate hygiene
+pub fn decode_expn_id<
+    'a,
+    D: Decoder,
+    F: FnOnce(&mut D, u32) -> Result<ExpnData, D::Error>,
+    G: FnOnce(CrateNum) -> &'a HygieneContext,
+>(
+    d: &mut D,
+    mode: ExpnDataDecodeMode<'a, G>,
+    decode_data: F,
+) -> Result<ExpnId, D::Error> {
+    let index = u32::decode(d)?;
+    let context = match mode {
+        ExpnDataDecodeMode::IncrComp(context) => context,
+        ExpnDataDecodeMode::Metadata(get_context) => {
+            let krate = CrateNum::decode(d)?;
+            get_context(krate)
+        }
+    };
+
+    // Do this after decoding, so that we decode a `CrateNum`
+    // if necessary
+    if index == ExpnId::root().as_u32() {
+        debug!("decode_expn_id: deserialized root");
+        return Ok(ExpnId::root());
+    }
+
+    let outer_expns = &context.remapped_expns;
+
+    // Ensure that the lock() temporary is dropped early
+    {
+        if let Some(expn_id) = outer_expns.lock().get(index as usize).copied().flatten() {
+            return Ok(expn_id);
+        }
     }
+
+    // Don't decode the data inside `HygieneData::with`, since we need to recursively decode
+    // other ExpnIds
+    let expn_data = decode_data(d, index)?;
+
+    let expn_id = HygieneData::with(|hygiene_data| {
+        let expn_id = ExpnId(hygiene_data.expn_data.len() as u32);
+        hygiene_data.expn_data.push(Some(expn_data));
+
+        // Drop lock() temporary early
+        {
+            let mut expns = outer_expns.lock();
+            let new_len = index as usize + 1;
+            if expns.len() < new_len {
+                expns.resize(new_len, None);
+            }
+            expns[index as usize] = Some(expn_id);
+        }
+        expn_id
+    });
+    return Ok(expn_id);
 }
+
+// Decodes `SyntaxContext`, using the provided `HygieneContext`
+// to track which `SyntaxContext`s we have already decoded.
+// The provided closure will be invoked to deserialize a `SyntaxContextData`
+// if we haven't already seen the id of the `SyntaxContext` we are deserializing.
+pub fn decode_syntax_context<
+    D: Decoder,
+    F: FnOnce(&mut D, u32) -> Result<SyntaxContextData, D::Error>,
+>(
+    d: &mut D,
+    context: &HygieneContext,
+    decode_data: F,
+) -> Result<SyntaxContext, D::Error> {
+    let raw_id: u32 = Decodable::decode(d)?;
+    if raw_id == 0 {
+        debug!("decode_syntax_context: deserialized root");
+        // The root is special
+        return Ok(SyntaxContext::root());
+    }
+
+    let outer_ctxts = &context.remapped_ctxts;
+
+    // Ensure that the lock() temporary is dropped early
+    {
+        if let Some(ctxt) = outer_ctxts.lock().get(raw_id as usize).copied().flatten() {
+            return Ok(ctxt);
+        }
+    }
+
+    // Allocate and store SyntaxContext id *before* calling the decoder function,
+    // as the SyntaxContextData may reference itself.
+    let new_ctxt = HygieneData::with(|hygiene_data| {
+        let new_ctxt = SyntaxContext(hygiene_data.syntax_context_data.len() as u32);
+        // Push a dummy SyntaxContextData to ensure that nobody else can get the
+        // same ID as us. This will be overwritten after call `decode_Data`
+        hygiene_data.syntax_context_data.push(SyntaxContextData {
+            outer_expn: ExpnId::root(),
+            outer_transparency: Transparency::Transparent,
+            parent: SyntaxContext::root(),
+            opaque: SyntaxContext::root(),
+            opaque_and_semitransparent: SyntaxContext::root(),
+            dollar_crate_name: kw::Invalid,
+        });
+        // Ensure that the lock() temporary is dropped early
+        {
+            let mut ctxts = outer_ctxts.lock();
+            let new_len = raw_id as usize + 1;
+            if ctxts.len() < new_len {
+                ctxts.resize(new_len, None);
+            }
+            ctxts[raw_id as usize] = Some(new_ctxt);
+        }
+        new_ctxt
+    });
+
+    // Don't try to decode data while holding the lock, since we need to
+    // be able to recursively decode a SyntaxContext
+    let mut ctxt_data = decode_data(d, raw_id)?;
+    // Reset `dollar_crate_name` so that it will be updated by `update_dollar_crate_names`
+    // We don't care what the encoding crate set this to - we want to resolve it
+    // from the perspective of the current compilation session
+    ctxt_data.dollar_crate_name = kw::DollarCrate;
+
+    // Overwrite the dummy data with our decoded SyntaxContextData
+    HygieneData::with(|hygiene_data| {
+        let dummy = std::mem::replace(
+            &mut hygiene_data.syntax_context_data[new_ctxt.as_u32() as usize],
+            ctxt_data,
+        );
+        // Make sure nothing weird happening while `decode_data` was running
+        assert_eq!(dummy.dollar_crate_name, kw::Invalid);
+    });
+
+    return Ok(new_ctxt);
+}
+
+pub fn num_syntax_ctxts() -> usize {
+    HygieneData::with(|data| data.syntax_context_data.len())
+}
+
+pub fn for_all_data_in<E, F: FnMut((u32, SyntaxContext, &SyntaxContextData)) -> Result<(), E>>(
+    ctxts: impl Iterator<Item = SyntaxContext>,
+    mut f: F,
+) -> Result<(), E> {
+    let all_data: Vec<_> = HygieneData::with(|data| {
+        ctxts.map(|ctxt| (ctxt, data.syntax_context_data[ctxt.0 as usize].clone())).collect()
+    });
+    for (ctxt, data) in all_data.into_iter() {
+        f((ctxt.0, ctxt, &data))?;
+    }
+    Ok(())
+}
+
+pub fn for_all_data<E, F: FnMut((u32, SyntaxContext, &SyntaxContextData)) -> Result<(), E>>(
+    mut f: F,
+) -> Result<(), E> {
+    let all_data = HygieneData::with(|data| data.syntax_context_data.clone());
+    for (i, data) in all_data.into_iter().enumerate() {
+        f((i as u32, SyntaxContext(i as u32), &data))?;
+    }
+    Ok(())
+}
+
+pub fn for_all_expn_data<E, F: FnMut(u32, &ExpnData) -> Result<(), E>>(mut f: F) -> Result<(), E> {
+    let all_data = HygieneData::with(|data| data.expn_data.clone());
+    for (i, data) in all_data.into_iter().enumerate() {
+        f(i as u32, &data.unwrap_or_else(|| panic!("Missing ExpnData!")))?;
+    }
+    Ok(())
+}
+
+pub fn raw_encode_syntax_context<E: Encoder>(
+    ctxt: SyntaxContext,
+    e: &mut E,
+) -> Result<(), E::Error> {
+    ctxt.0.encode(e)
+}
+
+pub fn raw_encode_expn_id<E: Encoder>(
+    expn: ExpnId,
+    mode: ExpnDataEncodeMode,
+    e: &mut E,
+) -> Result<(), E::Error> {
+    match mode {
+        ExpnDataEncodeMode::IncrComp => expn.0.encode(e),
+        ExpnDataEncodeMode::Metadata => {
+            let data = expn.expn_data();
+            data.orig_id.expect("Missing orig_id").encode(e)?;
+            data.krate.encode(e)
+        }
+    }
+}
+
+pub enum ExpnDataEncodeMode {
+    IncrComp,
+    Metadata,
+}
+
+pub enum ExpnDataDecodeMode<'a, F: FnOnce(CrateNum) -> &'a HygieneContext> {
+    IncrComp(&'a HygieneContext),
+    Metadata(F),
+}
+
+impl<'a> ExpnDataDecodeMode<'a, Box<dyn FnOnce(CrateNum) -> &'a HygieneContext>> {
+    pub fn incr_comp(ctxt: &'a HygieneContext) -> Self {
+        ExpnDataDecodeMode::IncrComp(ctxt)
+    }
+}
+
+impl UseSpecializedEncodable for SyntaxContext {}
+impl UseSpecializedDecodable for SyntaxContext {}
diff --git a/src/librustc_span/lib.rs b/src/librustc_span/lib.rs
index 666080028c1..f49e7f15a5c 100644
--- a/src/librustc_span/lib.rs
+++ b/src/librustc_span/lib.rs
@@ -12,6 +12,7 @@
 #![feature(nll)]
 #![feature(optin_builtin_traits)]
 #![feature(min_specialization)]
+#![feature(option_expect_none)]
 
 // FIXME(#56935): Work around ICEs during cross-compilation.
 #[allow(unused)]
@@ -30,8 +31,8 @@ pub mod edition;
 use edition::Edition;
 pub mod hygiene;
 pub use hygiene::SyntaxContext;
-use hygiene::Transparency;
 pub use hygiene::{DesugaringKind, ExpnData, ExpnId, ExpnKind, ForLoopLoc, MacroKind};
+use hygiene::{Transparency, NUM_TRANSPARENCIES};
 pub mod def_id;
 use def_id::{CrateNum, DefId, LOCAL_CRATE};
 mod span_encoding;
@@ -44,7 +45,6 @@ mod analyze_source_file;
 pub mod fatal_error;
 
 use rustc_data_structures::fingerprint::Fingerprint;
-use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_data_structures::sync::{Lock, Lrc};
 
@@ -86,6 +86,9 @@ impl SessionGlobals {
     }
 }
 
+// If this ever becomes non thread-local, `decode_syntax_context`
+// and `decode_expn_id` will need to be updated to handle concurrent
+// deserialization.
 scoped_tls::scoped_thread_local!(pub static SESSION_GLOBALS: SessionGlobals);
 
 // FIXME: Perhaps this should not implement Rustc{Decodable, Encodable}
@@ -1733,8 +1736,9 @@ fn lookup_line(lines: &[BytePos], pos: BytePos) -> isize {
 /// This is a hack to allow using the `HashStable_Generic` derive macro
 /// instead of implementing everything in librustc_middle.
 pub trait HashStableContext {
-    fn hash_spans(&self) -> bool;
     fn hash_def_id(&mut self, _: DefId, hasher: &mut StableHasher);
+    fn hash_crate_num(&mut self, _: CrateNum, hasher: &mut StableHasher);
+    fn hash_spans(&self) -> bool;
     fn byte_pos_to_line_and_col(
         &mut self,
         byte: BytePos,
@@ -1757,15 +1761,14 @@ where
     fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
         const TAG_VALID_SPAN: u8 = 0;
         const TAG_INVALID_SPAN: u8 = 1;
-        const TAG_EXPANSION: u8 = 0;
-        const TAG_NO_EXPANSION: u8 = 1;
 
         if !ctx.hash_spans() {
             return;
         }
 
         if *self == DUMMY_SP {
-            return std::hash::Hash::hash(&TAG_INVALID_SPAN, hasher);
+            std::hash::Hash::hash(&TAG_INVALID_SPAN, hasher);
+            return;
         }
 
         // If this is not an empty or invalid span, we want to hash the last
@@ -1775,12 +1778,16 @@ where
         let (file_lo, line_lo, col_lo) = match ctx.byte_pos_to_line_and_col(span.lo) {
             Some(pos) => pos,
             None => {
-                return std::hash::Hash::hash(&TAG_INVALID_SPAN, hasher);
+                std::hash::Hash::hash(&TAG_INVALID_SPAN, hasher);
+                span.ctxt.hash_stable(ctx, hasher);
+                return;
             }
         };
 
         if !file_lo.contains(span.hi) {
-            return std::hash::Hash::hash(&TAG_INVALID_SPAN, hasher);
+            std::hash::Hash::hash(&TAG_INVALID_SPAN, hasher);
+            span.ctxt.hash_stable(ctx, hasher);
+            return;
         }
 
         std::hash::Hash::hash(&TAG_VALID_SPAN, hasher);
@@ -1793,8 +1800,16 @@ where
         let len = ((span.hi - span.lo).0 as u64) << 32;
         let line_col_len = col | line | len;
         std::hash::Hash::hash(&line_col_len, hasher);
+        span.ctxt.hash_stable(ctx, hasher);
+    }
+}
 
-        if span.ctxt == SyntaxContext::root() {
+impl<CTX: HashStableContext> HashStable<CTX> for SyntaxContext {
+    fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
+        const TAG_EXPANSION: u8 = 0;
+        const TAG_NO_EXPANSION: u8 = 1;
+
+        if *self == SyntaxContext::root() {
             TAG_NO_EXPANSION.hash_stable(ctx, hasher);
         } else {
             TAG_EXPANSION.hash_stable(ctx, hasher);
@@ -1803,21 +1818,39 @@ where
             // times, we cache a stable hash of it and hash that instead of
             // recursing every time.
             thread_local! {
-                static CACHE: RefCell<FxHashMap<hygiene::ExpnId, u64>> = Default::default();
+                static CACHE: RefCell<Vec<Option<[Option<u64>; NUM_TRANSPARENCIES]>>> = Default::default();
             }
 
             let sub_hash: u64 = CACHE.with(|cache| {
-                let expn_id = span.ctxt.outer_expn();
+                let (expn_id, transparency, _) = self.outer_mark_with_data();
+                let index = expn_id.as_u32() as usize;
 
-                if let Some(&sub_hash) = cache.borrow().get(&expn_id) {
-                    return sub_hash;
+                if let Some(sub_hash_cache) = cache.borrow().get(index).copied().flatten() {
+                    if let Some(sub_hash) = sub_hash_cache[transparency as usize] {
+                        return sub_hash;
+                    }
                 }
 
+                let new_len = index + 1;
+
                 let mut hasher = StableHasher::new();
                 expn_id.expn_data().hash_stable(ctx, &mut hasher);
+                transparency.hash_stable(ctx, &mut hasher);
+
                 let sub_hash: Fingerprint = hasher.finish();
                 let sub_hash = sub_hash.to_smaller_hash();
-                cache.borrow_mut().insert(expn_id, sub_hash);
+
+                let mut cache = cache.borrow_mut();
+                if cache.len() < new_len {
+                    cache.resize(new_len, None);
+                }
+                if let Some(mut sub_hash_cache) = cache[index] {
+                    sub_hash_cache[transparency as usize] = Some(sub_hash);
+                } else {
+                    let mut sub_hash_cache = [None; NUM_TRANSPARENCIES];
+                    sub_hash_cache[transparency as usize] = Some(sub_hash);
+                    cache[index] = Some(sub_hash_cache);
+                }
                 sub_hash
             });
 
diff --git a/src/test/ui/hygiene/auxiliary/needs_hygiene.rs b/src/test/ui/hygiene/auxiliary/needs_hygiene.rs
new file mode 100644
index 00000000000..3df6450fd3e
--- /dev/null
+++ b/src/test/ui/hygiene/auxiliary/needs_hygiene.rs
@@ -0,0 +1,5 @@
+#![feature(decl_macro)]
+macro x() { struct MyStruct; }
+
+x!();
+x!();
diff --git a/src/test/ui/hygiene/cross_crate_hygiene.rs b/src/test/ui/hygiene/cross_crate_hygiene.rs
new file mode 100644
index 00000000000..75742960b7e
--- /dev/null
+++ b/src/test/ui/hygiene/cross_crate_hygiene.rs
@@ -0,0 +1,8 @@
+// check-pass
+// aux-build:needs_hygiene.rs
+
+extern crate needs_hygiene;
+
+use needs_hygiene::*;
+
+fn main() {}
diff --git a/src/test/ui/hygiene/panic-location.rs b/src/test/ui/hygiene/panic-location.rs
new file mode 100644
index 00000000000..5cf169dfb14
--- /dev/null
+++ b/src/test/ui/hygiene/panic-location.rs
@@ -0,0 +1,10 @@
+// run-fail
+// check-run-results
+// exec-env:RUST_BACKTRACE=0
+//
+// Regression test for issue #70963
+// The captured stderr from this test reports a location
+// inside `VecDeque::with_capacity`, instead of `<::core::macros::panic macros>`
+fn main() {
+    std::collections::VecDeque::<String>::with_capacity(!0);
+}
diff --git a/src/test/ui/hygiene/panic-location.run.stderr b/src/test/ui/hygiene/panic-location.run.stderr
new file mode 100644
index 00000000000..abdccf63b52
--- /dev/null
+++ b/src/test/ui/hygiene/panic-location.run.stderr
@@ -0,0 +1,2 @@
+thread 'main' panicked at 'capacity overflow', $SRC_DIR/liballoc/collections/vec_deque.rs:LL:COL
+note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
diff --git a/src/test/ui/proc-macro/dollar-crate-issue-57089.stdout b/src/test/ui/proc-macro/dollar-crate-issue-57089.stdout
index 5d93144b445..43b4a05468b 100644
--- a/src/test/ui/proc-macro/dollar-crate-issue-57089.stdout
+++ b/src/test/ui/proc-macro/dollar-crate-issue-57089.stdout
@@ -2,79 +2,79 @@ PRINT-BANG INPUT (DISPLAY): struct M($crate :: S) ;
 PRINT-BANG INPUT (DEBUG): TokenStream [
     Ident {
         ident: "struct",
-        span: #3 bytes(LO..HI),
+        span: #6 bytes(LO..HI),
     },
     Ident {
         ident: "M",
-        span: #3 bytes(LO..HI),
+        span: #6 bytes(LO..HI),
     },
     Group {
         delimiter: Parenthesis,
         stream: TokenStream [
             Ident {
                 ident: "$crate",
-                span: #3 bytes(LO..HI),
+                span: #6 bytes(LO..HI),
             },
             Punct {
                 ch: ':',
                 spacing: Joint,
-                span: #3 bytes(LO..HI),
+                span: #6 bytes(LO..HI),
             },
             Punct {
                 ch: ':',
                 spacing: Alone,
-                span: #3 bytes(LO..HI),
+                span: #6 bytes(LO..HI),
             },
             Ident {
                 ident: "S",
-                span: #3 bytes(LO..HI),
+                span: #6 bytes(LO..HI),
             },
         ],
-        span: #3 bytes(LO..HI),
+        span: #6 bytes(LO..HI),
     },
     Punct {
         ch: ';',
         spacing: Alone,
-        span: #3 bytes(LO..HI),
+        span: #6 bytes(LO..HI),
     },
 ]
 PRINT-ATTR INPUT (DISPLAY): struct A($crate :: S) ;
 PRINT-ATTR INPUT (DEBUG): TokenStream [
     Ident {
         ident: "struct",
-        span: #3 bytes(LO..HI),
+        span: #6 bytes(LO..HI),
     },
     Ident {
         ident: "A",
-        span: #3 bytes(LO..HI),
+        span: #6 bytes(LO..HI),
     },
     Group {
         delimiter: Parenthesis,
         stream: TokenStream [
             Ident {
                 ident: "$crate",
-                span: #3 bytes(LO..HI),
+                span: #6 bytes(LO..HI),
             },
             Punct {
                 ch: ':',
                 spacing: Joint,
-                span: #3 bytes(LO..HI),
+                span: #6 bytes(LO..HI),
             },
             Punct {
                 ch: ':',
                 spacing: Alone,
-                span: #3 bytes(LO..HI),
+                span: #6 bytes(LO..HI),
             },
             Ident {
                 ident: "S",
-                span: #3 bytes(LO..HI),
+                span: #6 bytes(LO..HI),
             },
         ],
-        span: #3 bytes(LO..HI),
+        span: #6 bytes(LO..HI),
     },
     Punct {
         ch: ';',
         spacing: Alone,
-        span: #3 bytes(LO..HI),
+        span: #6 bytes(LO..HI),
     },
 ]
diff --git a/src/test/ui/proc-macro/dollar-crate-issue-62325.stdout b/src/test/ui/proc-macro/dollar-crate-issue-62325.stdout
index e4212377626..163f573522f 100644
--- a/src/test/ui/proc-macro/dollar-crate-issue-62325.stdout
+++ b/src/test/ui/proc-macro/dollar-crate-issue-62325.stdout
@@ -2,109 +2,109 @@ PRINT-ATTR INPUT (DISPLAY): struct A(identity ! ($crate :: S)) ;
 PRINT-ATTR INPUT (DEBUG): TokenStream [
     Ident {
         ident: "struct",
-        span: #3 bytes(LO..HI),
+        span: #6 bytes(LO..HI),
     },
     Ident {
         ident: "A",
-        span: #3 bytes(LO..HI),
+        span: #6 bytes(LO..HI),
     },
     Group {
         delimiter: Parenthesis,
         stream: TokenStream [
             Ident {
                 ident: "identity",
-                span: #3 bytes(LO..HI),
+                span: #6 bytes(LO..HI),
             },
             Punct {
                 ch: '!',
                 spacing: Alone,
-                span: #3 bytes(LO..HI),
+                span: #6 bytes(LO..HI),
             },
             Group {
                 delimiter: Parenthesis,
                 stream: TokenStream [
                     Ident {
                         ident: "$crate",
-                        span: #3 bytes(LO..HI),
+                        span: #6 bytes(LO..HI),
                     },
                     Punct {
                         ch: ':',
                         spacing: Joint,
-                        span: #3 bytes(LO..HI),
+                        span: #6 bytes(LO..HI),
                     },
                     Punct {
                         ch: ':',
                         spacing: Alone,
-                        span: #3 bytes(LO..HI),
+                        span: #6 bytes(LO..HI),
                     },
                     Ident {
                         ident: "S",
-                        span: #3 bytes(LO..HI),
+                        span: #6 bytes(LO..HI),
                     },
                 ],
-                span: #3 bytes(LO..HI),
+                span: #6 bytes(LO..HI),
             },
         ],
-        span: #3 bytes(LO..HI),
+        span: #6 bytes(LO..HI),
     },
     Punct {
         ch: ';',
         spacing: Alone,
-        span: #3 bytes(LO..HI),
+        span: #6 bytes(LO..HI),
     },
 ]
 PRINT-ATTR INPUT (DISPLAY): struct B(identity ! ($crate :: S)) ;
 PRINT-ATTR INPUT (DEBUG): TokenStream [
     Ident {
         ident: "struct",
-        span: #10 bytes(LO..HI),
+        span: #13 bytes(LO..HI),
     },
     Ident {
         ident: "B",
-        span: #10 bytes(LO..HI),
+        span: #13 bytes(LO..HI),
     },
     Group {
         delimiter: Parenthesis,
         stream: TokenStream [
             Ident {
                 ident: "identity",
-                span: #10 bytes(LO..HI),
+                span: #13 bytes(LO..HI),
             },
             Punct {
                 ch: '!',
                 spacing: Alone,
-                span: #10 bytes(LO..HI),
+                span: #13 bytes(LO..HI),
             },
             Group {
                 delimiter: Parenthesis,
                 stream: TokenStream [
                     Ident {
                         ident: "$crate",
-                        span: #10 bytes(LO..HI),
+                        span: #13 bytes(LO..HI),
                     },
                     Punct {
                         ch: ':',
                         spacing: Joint,
-                        span: #10 bytes(LO..HI),
+                        span: #13 bytes(LO..HI),
                     },
                     Punct {
                         ch: ':',
                         spacing: Alone,
-                        span: #10 bytes(LO..HI),
+                        span: #13 bytes(LO..HI),
                     },
                     Ident {
                         ident: "S",
-                        span: #10 bytes(LO..HI),
+                        span: #13 bytes(LO..HI),
                     },
                 ],
-                span: #10 bytes(LO..HI),
+                span: #13 bytes(LO..HI),
             },
         ],
-        span: #10 bytes(LO..HI),
+        span: #13 bytes(LO..HI),
     },
     Punct {
         ch: ';',
         spacing: Alone,
-        span: #10 bytes(LO..HI),
+        span: #13 bytes(LO..HI),
     },
 ]
diff --git a/src/test/ui/proc-macro/dollar-crate.stdout b/src/test/ui/proc-macro/dollar-crate.stdout
index 8a7406b1a3d..69105b23cf9 100644
--- a/src/test/ui/proc-macro/dollar-crate.stdout
+++ b/src/test/ui/proc-macro/dollar-crate.stdout
@@ -2,239 +2,239 @@ PRINT-BANG INPUT (DISPLAY): struct M($crate :: S) ;
 PRINT-BANG INPUT (DEBUG): TokenStream [
     Ident {
         ident: "struct",
-        span: #3 bytes(LO..HI),
+        span: #6 bytes(LO..HI),
     },
     Ident {
         ident: "M",
-        span: #3 bytes(LO..HI),
+        span: #6 bytes(LO..HI),
     },
     Group {
         delimiter: Parenthesis,
         stream: TokenStream [
             Ident {
                 ident: "$crate",
-                span: #3 bytes(LO..HI),
+                span: #6 bytes(LO..HI),
             },
             Punct {
                 ch: ':',
                 spacing: Joint,
-                span: #3 bytes(LO..HI),
+                span: #6 bytes(LO..HI),
             },
             Punct {
                 ch: ':',
                 spacing: Alone,
-                span: #3 bytes(LO..HI),
+                span: #6 bytes(LO..HI),
             },
             Ident {
                 ident: "S",
-                span: #3 bytes(LO..HI),
+                span: #6 bytes(LO..HI),
             },
         ],
-        span: #3 bytes(LO..HI),
+        span: #6 bytes(LO..HI),
     },
     Punct {
         ch: ';',
         spacing: Alone,
-        span: #3 bytes(LO..HI),
+        span: #6 bytes(LO..HI),
     },
 ]
 PRINT-ATTR INPUT (DISPLAY): struct A($crate :: S) ;
 PRINT-ATTR INPUT (DEBUG): TokenStream [
     Ident {
         ident: "struct",
-        span: #3 bytes(LO..HI),
+        span: #6 bytes(LO..HI),
     },
     Ident {
         ident: "A",
-        span: #3 bytes(LO..HI),
+        span: #6 bytes(LO..HI),
     },
     Group {
         delimiter: Parenthesis,
         stream: TokenStream [
             Ident {
                 ident: "$crate",
-                span: #3 bytes(LO..HI),
+                span: #6 bytes(LO..HI),
             },
             Punct {
                 ch: ':',
                 spacing: Joint,
-                span: #3 bytes(LO..HI),
+                span: #6 bytes(LO..HI),
             },
             Punct {
                 ch: ':',
                 spacing: Alone,
-                span: #3 bytes(LO..HI),
+                span: #6 bytes(LO..HI),
             },
             Ident {
                 ident: "S",
-                span: #3 bytes(LO..HI),
+                span: #6 bytes(LO..HI),
             },
         ],
-        span: #3 bytes(LO..HI),
+        span: #6 bytes(LO..HI),
     },
     Punct {
         ch: ';',
         spacing: Alone,
-        span: #3 bytes(LO..HI),
+        span: #6 bytes(LO..HI),
     },
 ]
 PRINT-DERIVE INPUT (DISPLAY): struct D($crate :: S) ;
 PRINT-DERIVE INPUT (DEBUG): TokenStream [
     Ident {
         ident: "struct",
-        span: #3 bytes(LO..HI),
+        span: #6 bytes(LO..HI),
     },
     Ident {
         ident: "D",
-        span: #3 bytes(LO..HI),
+        span: #6 bytes(LO..HI),
     },
     Group {
         delimiter: Parenthesis,
         stream: TokenStream [
             Ident {
                 ident: "$crate",
-                span: #3 bytes(LO..HI),
+                span: #6 bytes(LO..HI),
             },
             Punct {
                 ch: ':',
                 spacing: Joint,
-                span: #3 bytes(LO..HI),
+                span: #6 bytes(LO..HI),
             },
             Punct {
                 ch: ':',
                 spacing: Alone,
-                span: #3 bytes(LO..HI),
+                span: #6 bytes(LO..HI),
             },
             Ident {
                 ident: "S",
-                span: #3 bytes(LO..HI),
+                span: #6 bytes(LO..HI),
             },
         ],
-        span: #3 bytes(LO..HI),
+        span: #6 bytes(LO..HI),
     },
     Punct {
         ch: ';',
         spacing: Alone,
-        span: #3 bytes(LO..HI),
+        span: #6 bytes(LO..HI),
     },
 ]
 PRINT-BANG INPUT (DISPLAY): struct M($crate :: S) ;
 PRINT-BANG INPUT (DEBUG): TokenStream [
     Ident {
         ident: "struct",
-        span: #13 bytes(LO..HI),
+        span: #16 bytes(LO..HI),
     },
     Ident {
         ident: "M",
-        span: #13 bytes(LO..HI),
+        span: #16 bytes(LO..HI),
     },
     Group {
         delimiter: Parenthesis,
         stream: TokenStream [
             Ident {
                 ident: "$crate",
-                span: #13 bytes(LO..HI),
+                span: #16 bytes(LO..HI),
             },
             Punct {
                 ch: ':',
                 spacing: Joint,
-                span: #13 bytes(LO..HI),
+                span: #16 bytes(LO..HI),
             },
             Punct {
                 ch: ':',
                 spacing: Alone,
-                span: #13 bytes(LO..HI),
+                span: #16 bytes(LO..HI),
             },
             Ident {
                 ident: "S",
-                span: #13 bytes(LO..HI),
+                span: #16 bytes(LO..HI),
             },
         ],
-        span: #13 bytes(LO..HI),
+        span: #16 bytes(LO..HI),
     },
     Punct {
         ch: ';',
         spacing: Alone,
-        span: #13 bytes(LO..HI),
+        span: #16 bytes(LO..HI),
     },
 ]
 PRINT-ATTR INPUT (DISPLAY): struct A($crate :: S) ;
 PRINT-ATTR INPUT (DEBUG): TokenStream [
     Ident {
         ident: "struct",
-        span: #13 bytes(LO..HI),
+        span: #16 bytes(LO..HI),
     },
     Ident {
         ident: "A",
-        span: #13 bytes(LO..HI),
+        span: #16 bytes(LO..HI),
     },
     Group {
         delimiter: Parenthesis,
         stream: TokenStream [
             Ident {
                 ident: "$crate",
-                span: #13 bytes(LO..HI),
+                span: #16 bytes(LO..HI),
             },
             Punct {
                 ch: ':',
                 spacing: Joint,
-                span: #13 bytes(LO..HI),
+                span: #16 bytes(LO..HI),
             },
             Punct {
                 ch: ':',
                 spacing: Alone,
-                span: #13 bytes(LO..HI),
+                span: #16 bytes(LO..HI),
             },
             Ident {
                 ident: "S",
-                span: #13 bytes(LO..HI),
+                span: #16 bytes(LO..HI),
             },
         ],
-        span: #13 bytes(LO..HI),
+        span: #16 bytes(LO..HI),
     },
     Punct {
         ch: ';',
         spacing: Alone,
-        span: #13 bytes(LO..HI),
+        span: #16 bytes(LO..HI),
     },
 ]
 PRINT-DERIVE INPUT (DISPLAY): struct D($crate :: S) ;
 PRINT-DERIVE INPUT (DEBUG): TokenStream [
     Ident {
         ident: "struct",
-        span: #13 bytes(LO..HI),
+        span: #16 bytes(LO..HI),
     },
     Ident {
         ident: "D",
-        span: #13 bytes(LO..HI),
+        span: #16 bytes(LO..HI),
     },
     Group {
         delimiter: Parenthesis,
         stream: TokenStream [
             Ident {
                 ident: "$crate",
-                span: #13 bytes(LO..HI),
+                span: #16 bytes(LO..HI),
             },
             Punct {
                 ch: ':',
                 spacing: Joint,
-                span: #13 bytes(LO..HI),
+                span: #16 bytes(LO..HI),
             },
             Punct {
                 ch: ':',
                 spacing: Alone,
-                span: #13 bytes(LO..HI),
+                span: #16 bytes(LO..HI),
             },
             Ident {
                 ident: "S",
-                span: #13 bytes(LO..HI),
+                span: #16 bytes(LO..HI),
             },
         ],
-        span: #13 bytes(LO..HI),
+        span: #16 bytes(LO..HI),
     },
     Punct {
         ch: ';',
         spacing: Alone,
-        span: #13 bytes(LO..HI),
+        span: #16 bytes(LO..HI),
     },
 ]
diff --git a/src/test/ui/proc-macro/input-interpolated.stdout b/src/test/ui/proc-macro/input-interpolated.stdout
index ee988d48b46..0c2d91ee0ab 100644
--- a/src/test/ui/proc-macro/input-interpolated.stdout
+++ b/src/test/ui/proc-macro/input-interpolated.stdout
@@ -8,7 +8,7 @@ PRINT-BANG INPUT (DEBUG): TokenStream [
                 span: #0 bytes(402..403),
             },
         ],
-        span: #3 bytes(269..271),
+        span: #6 bytes(269..271),
     },
 ]
 PRINT-ATTR INPUT (DISPLAY): const A : u8 = 0 ;
diff --git a/src/test/ui/proc-macro/meta-macro-hygiene.stdout b/src/test/ui/proc-macro/meta-macro-hygiene.stdout
index daca40eda90..95f89b46d05 100644
--- a/src/test/ui/proc-macro/meta-macro-hygiene.stdout
+++ b/src/test/ui/proc-macro/meta-macro-hygiene.stdout
@@ -1,4 +1,4 @@
-Def site: $DIR/auxiliary/make-macro.rs:7:9: 10:10 (#3)
+Def site: $DIR/auxiliary/make-macro.rs:7:9: 10:10 (#6)
 #![feature /* 0#0 */(prelude_import)]
 #[prelude_import /* 0#1 */]
 use std /* 0#1 */::prelude /* 0#1 */::v1 /* 0#1 */::*;
@@ -21,12 +21,19 @@ Expansions:
 0: parent: ExpnId(0), call_site_ctxt: #0, def_site_ctxt: #0, kind: Root
 1: parent: ExpnId(0), call_site_ctxt: #0, def_site_ctxt: #0, kind: AstPass(StdImports)
 2: parent: ExpnId(0), call_site_ctxt: #0, def_site_ctxt: #0, kind: Macro(Bang, "meta_macro::print_def_site")
+3: parent: ExpnId(0), call_site_ctxt: #0, def_site_ctxt: #0, kind: Macro(Bang, "cfg_if")
+4: parent: ExpnId(3), call_site_ctxt: #4, def_site_ctxt: #0, kind: Macro(Bang, "$crate::cfg_if")
+5: parent: ExpnId(4), call_site_ctxt: #5, def_site_ctxt: #0, kind: Macro(Bang, "$crate::cfg_if")
+6: parent: ExpnId(5), call_site_ctxt: #0, def_site_ctxt: #0, kind: Macro(Bang, "features")
 
 SyntaxContexts:
 #0: parent: #0, outer_mark: (ExpnId(0), Opaque)
 #1: parent: #0, outer_mark: (ExpnId(1), Opaque)
 #2: parent: #0, outer_mark: (ExpnId(1), Transparent)
-#3: parent: #0, outer_mark: (ExpnId(2), Opaque)
-#4: parent: #0, outer_mark: (ExpnId(2), Transparent)
-#5: parent: #0, outer_mark: (ExpnId(2), SemiTransparent)
+#3: parent: #0, outer_mark: (ExpnId(6), SemiTransparent)
+#4: parent: #0, outer_mark: (ExpnId(3), SemiTransparent)
+#5: parent: #0, outer_mark: (ExpnId(4), SemiTransparent)
+#6: parent: #0, outer_mark: (ExpnId(2), Opaque)
+#7: parent: #0, outer_mark: (ExpnId(2), Transparent)
+#8: parent: #0, outer_mark: (ExpnId(2), SemiTransparent)
 */
diff --git a/src/test/ui/proc-macro/meta-macro.stdout b/src/test/ui/proc-macro/meta-macro.stdout
index fa79f72137f..006c659df0b 100644
--- a/src/test/ui/proc-macro/meta-macro.stdout
+++ b/src/test/ui/proc-macro/meta-macro.stdout
@@ -1 +1 @@
-Def site: $DIR/auxiliary/make-macro.rs:7:9: 10:10 (#3)
+Def site: $DIR/auxiliary/make-macro.rs:7:9: 10:10 (#6)
diff --git a/src/test/ui/proc-macro/nested-macro-rules.stdout b/src/test/ui/proc-macro/nested-macro-rules.stdout
index e4cfe020324..7508231eb8c 100644
--- a/src/test/ui/proc-macro/nested-macro-rules.stdout
+++ b/src/test/ui/proc-macro/nested-macro-rules.stdout
@@ -5,10 +5,10 @@ PRINT-BANG INPUT (DEBUG): TokenStream [
         stream: TokenStream [
             Ident {
                 ident: "FirstStruct",
-                span: $DIR/auxiliary/nested-macro-rules.rs:15:14: 15:25 (#3),
+                span: $DIR/auxiliary/nested-macro-rules.rs:15:14: 15:25 (#8),
             },
         ],
-        span: $DIR/auxiliary/nested-macro-rules.rs:9:27: 9:32 (#3),
+        span: $DIR/auxiliary/nested-macro-rules.rs:9:27: 9:32 (#7),
     },
 ]
 PRINT-BANG INPUT (DISPLAY): SecondStruct
@@ -18,9 +18,9 @@ PRINT-BANG INPUT (DEBUG): TokenStream [
         stream: TokenStream [
             Ident {
                 ident: "SecondStruct",
-                span: $DIR/nested-macro-rules.rs:18:38: 18:50 (#9),
+                span: $DIR/nested-macro-rules.rs:18:38: 18:50 (#14),
             },
         ],
-        span: $DIR/auxiliary/nested-macro-rules.rs:9:27: 9:32 (#8),
+        span: $DIR/auxiliary/nested-macro-rules.rs:9:27: 9:32 (#13),
     },
 ]
diff --git a/src/test/ui/proc-macro/nodelim-groups.stdout b/src/test/ui/proc-macro/nodelim-groups.stdout
index 75a189a9fcd..ab7df9b9e98 100644
--- a/src/test/ui/proc-macro/nodelim-groups.stdout
+++ b/src/test/ui/proc-macro/nodelim-groups.stdout
@@ -4,7 +4,7 @@ PRINT-BANG INPUT (DEBUG): TokenStream [
         kind: Str,
         symbol: "hi",
         suffix: None,
-        span: $DIR/nodelim-groups.rs:13:42: 13:46 (#3),
+        span: $DIR/nodelim-groups.rs:13:42: 13:46 (#6),
     },
     Group {
         delimiter: None,
@@ -44,7 +44,7 @@ PRINT-BANG INPUT (DEBUG): TokenStream [
                 span: $DIR/nodelim-groups.rs:17:27: 17:28 (#0),
             },
         ],
-        span: $DIR/nodelim-groups.rs:13:47: 13:51 (#3),
+        span: $DIR/nodelim-groups.rs:13:47: 13:51 (#6),
     },
     Group {
         delimiter: Parenthesis,
@@ -53,21 +53,21 @@ PRINT-BANG INPUT (DEBUG): TokenStream [
                 kind: Integer,
                 symbol: "1",
                 suffix: None,
-                span: $DIR/nodelim-groups.rs:13:53: 13:54 (#3),
+                span: $DIR/nodelim-groups.rs:13:53: 13:54 (#6),
             },
             Punct {
                 ch: '+',
                 spacing: Alone,
-                span: $DIR/nodelim-groups.rs:13:55: 13:56 (#3),
+                span: $DIR/nodelim-groups.rs:13:55: 13:56 (#6),
             },
             Literal {
                 kind: Integer,
                 symbol: "1",
                 suffix: None,
-                span: $DIR/nodelim-groups.rs:13:57: 13:58 (#3),
+                span: $DIR/nodelim-groups.rs:13:57: 13:58 (#6),
             },
         ],
-        span: $DIR/nodelim-groups.rs:13:52: 13:59 (#3),
+        span: $DIR/nodelim-groups.rs:13:52: 13:59 (#6),
     },
 ]
 PRINT-BANG INPUT (DISPLAY): "hi" "hello".len() + "world".len() (1 + 1)
@@ -77,7 +77,7 @@ PRINT-BANG INPUT (DEBUG): TokenStream [
         kind: Str,
         symbol: "hi",
         suffix: None,
-        span: $DIR/nodelim-groups.rs:13:42: 13:46 (#8),
+        span: $DIR/nodelim-groups.rs:13:42: 13:46 (#11),
     },
     Group {
         delimiter: None,
@@ -86,49 +86,49 @@ PRINT-BANG INPUT (DEBUG): TokenStream [
                 kind: Str,
                 symbol: "hello",
                 suffix: None,
-                span: $DIR/nodelim-groups.rs:13:47: 13:51 (#8),
+                span: $DIR/nodelim-groups.rs:13:47: 13:51 (#11),
             },
             Punct {
                 ch: '.',
                 spacing: Alone,
-                span: $DIR/nodelim-groups.rs:13:47: 13:51 (#8),
+                span: $DIR/nodelim-groups.rs:13:47: 13:51 (#11),
             },
             Ident {
                 ident: "len",
-                span: $DIR/nodelim-groups.rs:13:47: 13:51 (#8),
+                span: $DIR/nodelim-groups.rs:13:47: 13:51 (#11),
             },
             Group {
                 delimiter: Parenthesis,
                 stream: TokenStream [],
-                span: $DIR/nodelim-groups.rs:13:47: 13:51 (#8),
+                span: $DIR/nodelim-groups.rs:13:47: 13:51 (#11),
             },
             Punct {
                 ch: '+',
                 spacing: Alone,
-                span: $DIR/nodelim-groups.rs:13:47: 13:51 (#8),
+                span: $DIR/nodelim-groups.rs:13:47: 13:51 (#11),
             },
             Literal {
                 kind: Str,
                 symbol: "world",
                 suffix: None,
-                span: $DIR/nodelim-groups.rs:13:47: 13:51 (#8),
+                span: $DIR/nodelim-groups.rs:13:47: 13:51 (#11),
             },
             Punct {
                 ch: '.',
                 spacing: Alone,
-                span: $DIR/nodelim-groups.rs:13:47: 13:51 (#8),
+                span: $DIR/nodelim-groups.rs:13:47: 13:51 (#11),
             },
             Ident {
                 ident: "len",
-                span: $DIR/nodelim-groups.rs:13:47: 13:51 (#8),
+                span: $DIR/nodelim-groups.rs:13:47: 13:51 (#11),
             },
             Group {
                 delimiter: Parenthesis,
                 stream: TokenStream [],
-                span: $DIR/nodelim-groups.rs:13:47: 13:51 (#8),
+                span: $DIR/nodelim-groups.rs:13:47: 13:51 (#11),
             },
         ],
-        span: $DIR/nodelim-groups.rs:13:47: 13:51 (#8),
+        span: $DIR/nodelim-groups.rs:13:47: 13:51 (#11),
     },
     Group {
         delimiter: Parenthesis,
@@ -137,20 +137,20 @@ PRINT-BANG INPUT (DEBUG): TokenStream [
                 kind: Integer,
                 symbol: "1",
                 suffix: None,
-                span: $DIR/nodelim-groups.rs:13:53: 13:54 (#8),
+                span: $DIR/nodelim-groups.rs:13:53: 13:54 (#11),
             },
             Punct {
                 ch: '+',
                 spacing: Alone,
-                span: $DIR/nodelim-groups.rs:13:55: 13:56 (#8),
+                span: $DIR/nodelim-groups.rs:13:55: 13:56 (#11),
             },
             Literal {
                 kind: Integer,
                 symbol: "1",
                 suffix: None,
-                span: $DIR/nodelim-groups.rs:13:57: 13:58 (#8),
+                span: $DIR/nodelim-groups.rs:13:57: 13:58 (#11),
             },
         ],
-        span: $DIR/nodelim-groups.rs:13:52: 13:59 (#8),
+        span: $DIR/nodelim-groups.rs:13:52: 13:59 (#11),
     },
 ]