Keep a parent LocalDefId in SpanData.

compiler/rustc_ast/src/attr/mod.rs

@@ -367,7 +367,7 @@ impl MetaItem {
             let is_first = i == 0;
             if !is_first {
                 let mod_sep_span =
-                    Span::new(last_pos, segment.ident.span.lo(), segment.ident.span.ctxt());
+                    Span::new(last_pos, segment.ident.span.lo(), segment.ident.span.ctxt(), None);
                 idents.push(TokenTree::token(token::ModSep, mod_sep_span).into());
             }
             idents.push(TokenTree::Token(Token::from_ast_ident(segment.ident)).into());

compiler/rustc_expand/src/proc_macro_server.rs

@@ -745,7 +745,7 @@ impl server::Span for Rustc<'_> {
         self.sess.source_map().lookup_char_pos(span.lo()).file
     }
     fn parent(&mut self, span: Self::Span) -> Option<Self::Span> {
-        span.parent()
+        span.parent_callsite()
     }
     fn source(&mut self, span: Self::Span) -> Self::Span {
         span.source_callsite()

compiler/rustc_metadata/src/rmeta/decoder.rs

@@ -536,7 +536,8 @@ impl<'a, 'tcx> Decodable<DecodeContext<'a, 'tcx>> for Span {
         let hi =
             (hi + source_file.translated_source_file.start_pos) - source_file.original_start_pos;
 
-        Ok(Span::new(lo, hi, ctxt))
+        // Do not try to decode parent for foreign spans.
+        Ok(Span::new(lo, hi, ctxt, None))
     }
 }
 

compiler/rustc_middle/src/ty/error.rs

@@ -964,7 +964,7 @@ fn foo(&self) -> Self::T { String::new() }
         {
             let (span, sugg) = if has_params {
                 let pos = span.hi() - BytePos(1);
-                let span = Span::new(pos, pos, span.ctxt());
+                let span = Span::new(pos, pos, span.ctxt(), span.parent());
                 (span, format!(", {} = {}", assoc.ident, ty))
             } else {
                 let item_args = self.format_generic_args(assoc_substs);

compiler/rustc_mir_transform/src/coverage/spans.rs

@@ -196,7 +196,11 @@ impl CoverageSpan {
     /// body_span), returns the macro name symbol.
     pub fn visible_macro(&self, body_span: Span) -> Option<Symbol> {
         if let Some(current_macro) = self.current_macro() {
-            if self.expn_span.parent().unwrap_or_else(|| bug!("macro must have a parent")).ctxt()
+            if self
+                .expn_span
+                .parent_callsite()
+                .unwrap_or_else(|| bug!("macro must have a parent"))
+                .ctxt()
                 == body_span.ctxt()
             {
                 return Some(current_macro);

compiler/rustc_parse/src/lib.rs

@@ -131,7 +131,7 @@ fn maybe_source_file_to_parser(
     let mut parser = stream_to_parser(sess, stream, None);
     parser.unclosed_delims = unclosed_delims;
     if parser.token == token::Eof {
-        parser.token.span = Span::new(end_pos, end_pos, parser.token.span.ctxt());
+        parser.token.span = Span::new(end_pos, end_pos, parser.token.span.ctxt(), None);
     }
 
     Ok(parser)

compiler/rustc_query_impl/src/on_disk_cache.rs

@@ -848,7 +848,7 @@ impl<'a, 'tcx> Decodable<CacheDecoder<'a, 'tcx>> for Span {
         let lo = file_lo.lines[line_lo - 1] + col_lo;
         let hi = lo + len;
 
-        Ok(Span::new(lo, hi, ctxt))
+        Ok(Span::new(lo, hi, ctxt, None))
     }
 }
 

compiler/rustc_resolve/src/late/diagnostics.rs

@@ -768,6 +768,7 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
                                             args[1].span.lo(),
                                             args.last().unwrap().span.hi(),
                                             call_span.ctxt(),
+                                            None,
                                         ))
                                     } else {
                                         None

compiler/rustc_span/src/lib.rs

@@ -41,7 +41,7 @@ use hygiene::Transparency;
 pub use hygiene::{DesugaringKind, ExpnKind, ForLoopLoc, MacroKind};
 pub use hygiene::{ExpnData, ExpnHash, ExpnId, LocalExpnId, SyntaxContext};
 pub mod def_id;
-use def_id::{CrateNum, DefId, DefPathHash, LOCAL_CRATE};
+use def_id::{CrateNum, DefId, DefPathHash, LocalDefId, LOCAL_CRATE};
 pub mod lev_distance;
 mod span_encoding;
 pub use span_encoding::{Span, DUMMY_SP};
@@ -434,24 +434,38 @@ pub struct SpanData {
     /// Information about where the macro came from, if this piece of
     /// code was created by a macro expansion.
     pub ctxt: SyntaxContext,
+    pub parent: Option<LocalDefId>,
 }
 
 impl SpanData {
     #[inline]
     pub fn span(&self) -> Span {
-        Span::new(self.lo, self.hi, self.ctxt)
+        Span::new(self.lo, self.hi, self.ctxt, self.parent)
     }
     #[inline]
     pub fn with_lo(&self, lo: BytePos) -> Span {
-        Span::new(lo, self.hi, self.ctxt)
+        Span::new(lo, self.hi, self.ctxt, self.parent)
     }
     #[inline]
     pub fn with_hi(&self, hi: BytePos) -> Span {
-        Span::new(self.lo, hi, self.ctxt)
+        Span::new(self.lo, hi, self.ctxt, self.parent)
     }
     #[inline]
     pub fn with_ctxt(&self, ctxt: SyntaxContext) -> Span {
-        Span::new(self.lo, self.hi, ctxt)
+        Span::new(self.lo, self.hi, ctxt, self.parent)
+    }
+    #[inline]
+    pub fn with_parent(&self, parent: Option<LocalDefId>) -> Span {
+        Span::new(self.lo, self.hi, self.ctxt, parent)
+    }
+    /// Returns `true` if this is a dummy span with any hygienic context.
+    #[inline]
+    pub fn is_dummy(self) -> bool {
+        self.lo.0 == 0 && self.hi.0 == 0
+    }
+    /// Returns `true` if `self` fully encloses `other`.
+    pub fn contains(self, other: Self) -> bool {
+        self.lo <= other.lo && other.hi <= self.hi
     }
 }
 
@@ -513,12 +527,19 @@ impl Span {
     pub fn with_ctxt(self, ctxt: SyntaxContext) -> Span {
         self.data().with_ctxt(ctxt)
     }
+    #[inline]
+    pub fn parent(self) -> Option<LocalDefId> {
+        self.data().parent
+    }
+    #[inline]
+    pub fn with_parent(self, ctxt: Option<LocalDefId>) -> Span {
+        self.data().with_parent(ctxt)
+    }
 
     /// Returns `true` if this is a dummy span with any hygienic context.
     #[inline]
     pub fn is_dummy(self) -> bool {
-        let span = self.data();
-        span.lo.0 == 0 && span.hi.0 == 0
+        self.data().is_dummy()
     }
 
     /// Returns `true` if this span comes from a macro or desugaring.
@@ -534,7 +555,7 @@ impl Span {
 
     #[inline]
     pub fn with_root_ctxt(lo: BytePos, hi: BytePos) -> Span {
-        Span::new(lo, hi, SyntaxContext::root())
+        Span::new(lo, hi, SyntaxContext::root(), None)
     }
 
     /// Returns a new span representing an empty span at the beginning of this span.
@@ -566,7 +587,7 @@ impl Span {
     pub fn contains(self, other: Span) -> bool {
         let span = self.data();
         let other = other.data();
-        span.lo <= other.lo && other.hi <= span.hi
+        span.contains(other)
     }
 
     /// Returns `true` if `self` touches `other`.
@@ -602,15 +623,15 @@ impl Span {
 
     /// The `Span` for the tokens in the previous macro expansion from which `self` was generated,
     /// if any.
-    pub fn parent(self) -> Option<Span> {
+    pub fn parent_callsite(self) -> Option<Span> {
         let expn_data = self.ctxt().outer_expn_data();
         if !expn_data.is_root() { Some(expn_data.call_site) } else { None }
     }
 
     /// Walk down the expansion ancestors to find a span that's contained within `outer`.
     pub fn find_ancestor_inside(mut self, outer: Span) -> Option<Span> {
         while !outer.contains(self) {
-            self = self.parent()?;
+            self = self.parent_callsite()?;
         }
         Some(self)
     }
@@ -731,6 +752,7 @@ impl Span {
             cmp::min(span_data.lo, end_data.lo),
             cmp::max(span_data.hi, end_data.hi),
             if span_data.ctxt == SyntaxContext::root() { end_data.ctxt } else { span_data.ctxt },
+            if span_data.parent == end_data.parent { span_data.parent } else { None },
         )
     }
 
@@ -748,6 +770,7 @@ impl Span {
             span.hi,
             end.lo,
             if end.ctxt == SyntaxContext::root() { end.ctxt } else { span.ctxt },
+            if span.parent == end.parent { span.parent } else { None },
         )
     }
 
@@ -765,6 +788,7 @@ impl Span {
             span.lo,
             end.lo,
             if end.ctxt == SyntaxContext::root() { end.ctxt } else { span.ctxt },
+            if span.parent == end.parent { span.parent } else { None },
         )
     }
 
@@ -774,6 +798,7 @@ impl Span {
             span.lo + BytePos::from_usize(inner.start),
             span.lo + BytePos::from_usize(inner.end),
             span.ctxt,
+            span.parent,
         )
     }
 
@@ -812,31 +837,31 @@ impl Span {
     pub fn remove_mark(&mut self) -> ExpnId {
         let mut span = self.data();
         let mark = span.ctxt.remove_mark();
-        *self = Span::new(span.lo, span.hi, span.ctxt);
+        *self = Span::new(span.lo, span.hi, span.ctxt, span.parent);
         mark
     }
 
     #[inline]
     pub fn adjust(&mut self, expn_id: ExpnId) -> Option<ExpnId> {
         let mut span = self.data();
         let mark = span.ctxt.adjust(expn_id);
-        *self = Span::new(span.lo, span.hi, span.ctxt);
+        *self = Span::new(span.lo, span.hi, span.ctxt, span.parent);
         mark
     }
 
     #[inline]
     pub fn normalize_to_macros_2_0_and_adjust(&mut self, expn_id: ExpnId) -> Option<ExpnId> {
         let mut span = self.data();
         let mark = span.ctxt.normalize_to_macros_2_0_and_adjust(expn_id);
-        *self = Span::new(span.lo, span.hi, span.ctxt);
+        *self = Span::new(span.lo, span.hi, span.ctxt, span.parent);
         mark
     }
 
     #[inline]
     pub fn glob_adjust(&mut self, expn_id: ExpnId, glob_span: Span) -> Option<Option<ExpnId>> {
         let mut span = self.data();
         let mark = span.ctxt.glob_adjust(expn_id, glob_span);
-        *self = Span::new(span.lo, span.hi, span.ctxt);
+        *self = Span::new(span.lo, span.hi, span.ctxt, span.parent);
         mark
     }
 
@@ -848,7 +873,7 @@ impl Span {
     ) -> Option<Option<ExpnId>> {
         let mut span = self.data();
         let mark = span.ctxt.reverse_glob_adjust(expn_id, glob_span);
-        *self = Span::new(span.lo, span.hi, span.ctxt);
+        *self = Span::new(span.lo, span.hi, span.ctxt, span.parent);
         mark
     }
 
@@ -900,7 +925,7 @@ impl<D: Decoder> Decodable<D> for Span {
             let lo = d.read_struct_field("lo", Decodable::decode)?;
             let hi = d.read_struct_field("hi", Decodable::decode)?;
 
-            Ok(Span::new(lo, hi, SyntaxContext::root()))
+            Ok(Span::new(lo, hi, SyntaxContext::root(), None))
         })
     }
 }
@@ -961,7 +986,7 @@ impl fmt::Debug for Span {
 
 impl fmt::Debug for SpanData {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        (*SPAN_DEBUG)(Span::new(self.lo, self.hi, self.ctxt), f)
+        (*SPAN_DEBUG)(Span::new(self.lo, self.hi, self.ctxt, self.parent), f)
     }
 }
 

compiler/rustc_span/src/source_map.rs

@@ -794,7 +794,7 @@ impl SourceMap {
             start_of_next_point.checked_add(width - 1).unwrap_or(start_of_next_point);
 
         let end_of_next_point = BytePos(cmp::max(sp.lo().0 + 1, end_of_next_point));
-        Span::new(BytePos(start_of_next_point), end_of_next_point, sp.ctxt())
+        Span::new(BytePos(start_of_next_point), end_of_next_point, sp.ctxt(), None)
     }
 
     /// Finds the width of the character, either before or after the end of provided span,

compiler/rustc_span/src/span_encoding.rs

@@ -4,6 +4,7 @@
 // The encoding format for inline spans were obtained by optimizing over crates in rustc/libstd.
 // See https://internals.rust-lang.org/t/rfc-compiler-refactoring-spans/1357/28
 
+use crate::def_id::LocalDefId;
 use crate::hygiene::SyntaxContext;
 use crate::{BytePos, SpanData};
 
@@ -70,19 +71,25 @@ pub const DUMMY_SP: Span = Span { base_or_index: 0, len_or_tag: 0, ctxt_or_zero:
 
 impl Span {
     #[inline]
-    pub fn new(mut lo: BytePos, mut hi: BytePos, ctxt: SyntaxContext) -> Self {
+    pub fn new(
+        mut lo: BytePos,
+        mut hi: BytePos,
+        ctxt: SyntaxContext,
+        parent: Option<LocalDefId>,
+    ) -> Self {
         if lo > hi {
             std::mem::swap(&mut lo, &mut hi);
         }
 
         let (base, len, ctxt2) = (lo.0, hi.0 - lo.0, ctxt.as_u32());
 
-        if len <= MAX_LEN && ctxt2 <= MAX_CTXT {
+        if len <= MAX_LEN && ctxt2 <= MAX_CTXT && parent.is_none() {
             // Inline format.
             Span { base_or_index: base, len_or_tag: len as u16, ctxt_or_zero: ctxt2 as u16 }
         } else {
             // Interned format.
-            let index = with_span_interner(|interner| interner.intern(&SpanData { lo, hi, ctxt }));
+            let index =
+                with_span_interner(|interner| interner.intern(&SpanData { lo, hi, ctxt, parent }));
             Span { base_or_index: index, len_or_tag: LEN_TAG, ctxt_or_zero: 0 }
         }
     }
@@ -96,6 +103,7 @@ impl Span {
                 lo: BytePos(self.base_or_index),
                 hi: BytePos(self.base_or_index + self.len_or_tag as u32),
                 ctxt: SyntaxContext::from_u32(self.ctxt_or_zero as u32),
+                parent: None,
             }
         } else {
             // Interned format.

compiler/rustc_typeck/src/check/demand.rs

@@ -589,7 +589,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     // E.g. for `&format!("")`, where we want the span to the
                     // `format!()` invocation instead of its expansion.
                     if let Some(call_span) =
-                        iter::successors(Some(expr.span), |s| s.parent()).find(|&s| sp.contains(s))
+                        iter::successors(Some(expr.span), |s| s.parent_callsite())
+                            .find(|&s| sp.contains(s))
                     {
                         if sm.span_to_snippet(call_span).is_ok() {
                             return Some((

src/tools/clippy/clippy_lints/src/attrs.rs

@@ -527,8 +527,8 @@ fn check_empty_line_after_outer_attr(cx: &EarlyContext<'_>, item: &rustc_ast::It
                 return;
             }
 
-            let begin_of_attr_to_item = Span::new(attr.span.lo(), item.span.lo(), item.span.ctxt());
-            let end_of_attr_to_item = Span::new(attr.span.hi(), item.span.lo(), item.span.ctxt());
+            let begin_of_attr_to_item = Span::new(attr.span.lo(), item.span.lo(), item.span.ctxt(), item.span.parent());
+            let end_of_attr_to_item = Span::new(attr.span.hi(), item.span.lo(), item.span.ctxt(), item.span.parent());
 
             if let Some(snippet) = snippet_opt(cx, end_of_attr_to_item) {
                 let lines = snippet.split('\n').collect::<Vec<_>>();

src/tools/clippy/clippy_lints/src/cognitive_complexity.rs

@@ -95,7 +95,7 @@ impl CognitiveComplexity {
                     });
 
                     if let Some((low, high)) = pos {
-                        Span::new(low, high, header_span.ctxt())
+                        Span::new(low, high, header_span.ctxt(), header_span.parent())
                     } else {
                         return;
                     }

src/tools/clippy/clippy_lints/src/copies.rs

@@ -472,7 +472,7 @@ fn emit_branches_sharing_code_lint(
 
         let mut span = moved_start.to(span_end);
         // Improve formatting if the inner block has indention (i.e. normal Rust formatting)
-        let test_span = Span::new(span.lo() - BytePos(4), span.lo(), span.ctxt());
+        let test_span = Span::new(span.lo() - BytePos(4), span.lo(), span.ctxt(), span.parent());
         if snippet_opt(cx, test_span)
             .map(|snip| snip == "    ")
             .unwrap_or_default()

src/tools/clippy/clippy_lints/src/doc.rs

@@ -665,6 +665,7 @@ fn check_text(cx: &LateContext<'_>, valid_idents: &FxHashSet<String>, text: &str
             span.lo() + BytePos::from_usize(offset),
             span.lo() + BytePos::from_usize(offset + word.len()),
             span.ctxt(),
+            span.parent(),
         );
 
         check_word(cx, word, span);

src/tools/clippy/clippy_lints/src/implicit_hasher.rs

@@ -130,7 +130,7 @@ impl<'tcx> LateLintPass<'tcx> for ImplicitHasher {
                         let pos = snippet_opt(cx, item.span.until(target.span()))
                             .and_then(|snip| Some(item.span.lo() + BytePos(snip.find("impl")? as u32 + 4)));
                         if let Some(pos) = pos {
-                            Span::new(pos, pos, item.span.data().ctxt)
+                            Span::new(pos, pos, item.span.ctxt(), item.span.parent())
                         } else {
                             return;
                         }
@@ -173,7 +173,7 @@ impl<'tcx> LateLintPass<'tcx> for ImplicitHasher {
                                     Some(item.span.lo() + BytePos((i + (&snip[i..]).find('(')?) as u32))
                                 })
                                 .expect("failed to create span for type parameters");
-                            Span::new(pos, pos, item.span.data().ctxt)
+                            Span::new(pos, pos, item.span.ctxt(), item.span.parent())
                         });
 
                         let mut ctr_vis = ImplicitHasherConstructorVisitor::new(cx, target);