incremental: Do not rely on default transparency when decoding syntax contexts

Using `ExpnId`s default transparency here instead of the mark's real transparency was actually incorrect.

src/librustc/ty/query/on_disk_cache.rs

@@ -23,7 +23,7 @@ use std::mem;
 use syntax::ast::NodeId;
 use syntax::source_map::{SourceMap, StableSourceFileId};
 use syntax_pos::{BytePos, Span, DUMMY_SP, SourceFile};
-use syntax_pos::hygiene::{ExpnId, SyntaxContext, ExpnData};
+use syntax_pos::hygiene::{ExpnId, SyntaxContext};
 
 const TAG_FILE_FOOTER: u128 = 0xC0FFEE_C0FFEE_C0FFEE_C0FFEE_C0FFEE;
 
@@ -593,8 +593,8 @@ impl<'a, 'tcx> SpecializedDecoder<Span> for CacheDecoder<'a, 'tcx> {
         // don't seem to be used after HIR lowering, so everything should be fine
         // as long as incremental compilation does not kick in before that.
         let location = || Span::with_root_ctxt(lo, hi);
-        let recover_from_expn_data = |this: &Self, expn_data, pos| {
-            let span = location().fresh_expansion(expn_data);
+        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
         };
@@ -603,9 +603,9 @@ impl<'a, 'tcx> SpecializedDecoder<Span> for CacheDecoder<'a, 'tcx> {
                 location()
             }
             TAG_EXPN_DATA_INLINE => {
-                let expn_data = Decodable::decode(self)?;
+                let (expn_data, transparency) = Decodable::decode(self)?;
                 recover_from_expn_data(
-                    self, expn_data, AbsoluteBytePos::new(self.opaque.position())
+                    self, expn_data, transparency, AbsoluteBytePos::new(self.opaque.position())
                 )
             }
             TAG_EXPN_DATA_SHORTHAND => {
@@ -614,9 +614,9 @@ impl<'a, 'tcx> SpecializedDecoder<Span> for CacheDecoder<'a, 'tcx> {
                 if let Some(ctxt) = cached_ctxt {
                     Span::new(lo, hi, ctxt)
                 } else {
-                    let expn_data =
-                        self.with_position(pos.to_usize(), |this| ExpnData::decode(this))?;
-                    recover_from_expn_data(self, expn_data, pos)
+                    let (expn_data, transparency) =
+                        self.with_position(pos.to_usize(), |this| Decodable::decode(this))?;
+                    recover_from_expn_data(self, expn_data, transparency, pos)
                 }
             }
             _ => {
@@ -819,7 +819,7 @@ where
         if span_data.ctxt == SyntaxContext::root() {
             TAG_NO_EXPN_DATA.encode(self)
         } else {
-            let (expn_id, expn_data) = span_data.ctxt.outer_expn_with_data();
+            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)
@@ -827,7 +827,7 @@ where
                 TAG_EXPN_DATA_INLINE.encode(self)?;
                 let pos = AbsoluteBytePos::new(self.position());
                 self.expn_data_shorthands.insert(expn_id, pos);
-                expn_data.encode(self)
+                (expn_data, transparency).encode(self)
             }
         }
     }

src/libsyntax_pos/hygiene.rs

@@ -183,8 +183,9 @@ impl HygieneData {
         self.syntax_context_data[ctxt.0 as usize].outer_expn
     }
 
-    fn outer_transparency(&self, ctxt: SyntaxContext) -> Transparency {
-        self.syntax_context_data[ctxt.0 as usize].outer_transparency
+    fn outer_mark(&self, ctxt: SyntaxContext) -> (ExpnId, Transparency) {
+        let data = &self.syntax_context_data[ctxt.0 as usize];
+        (data.outer_expn, data.outer_transparency)
     }
 
     fn parent_ctxt(&self, ctxt: SyntaxContext) -> SyntaxContext {
@@ -200,7 +201,7 @@ impl HygieneData {
     fn marks(&self, mut ctxt: SyntaxContext) -> Vec<(ExpnId, Transparency)> {
         let mut marks = Vec::new();
         while ctxt != SyntaxContext::root() {
-            marks.push((self.outer_expn(ctxt), self.outer_transparency(ctxt)));
+            marks.push(self.outer_mark(ctxt));
             ctxt = self.parent_ctxt(ctxt);
         }
         marks.reverse();
@@ -535,13 +536,11 @@ impl SyntaxContext {
         HygieneData::with(|data| data.expn_data(data.outer_expn(self)).clone())
     }
 
-    /// `ctxt.outer_expn_with_data()` is equivalent to but faster than
-    /// `{ let outer = ctxt.outer_expn(); (outer, outer.expn_data()) }`.
     #[inline]
-    pub fn outer_expn_with_data(self) -> (ExpnId, ExpnData) {
+    pub fn outer_mark_with_data(self) -> (ExpnId, Transparency, ExpnData) {
         HygieneData::with(|data| {
-            let outer = data.outer_expn(self);
-            (outer, data.expn_data(outer).clone())
+            let (expn_id, transparency) = data.outer_mark(self);
+            (expn_id, transparency, data.expn_data(expn_id).clone())
         })
     }
 
@@ -563,9 +562,18 @@ impl Span {
     /// The returned span belongs to the created expansion and has the new properties,
     /// but its location is inherited from the current span.
     pub fn fresh_expansion(self, expn_data: ExpnData) -> Span {
+        let transparency = expn_data.default_transparency;
+        self.fresh_expansion_with_transparency(expn_data, transparency)
+    }
+
+    pub fn fresh_expansion_with_transparency(
+        self, expn_data: ExpnData, transparency: Transparency
+    ) -> Span {
         HygieneData::with(|data| {
             let expn_id = data.fresh_expn(Some(expn_data));
-            self.with_ctxt(data.apply_mark(SyntaxContext::root(), expn_id))
+            self.with_ctxt(data.apply_mark_with_transparency(
+                SyntaxContext::root(), expn_id, transparency
+            ))
         })
     }
 }