Auto merge of #118517 - petrochenkov:span2, r=<try>

[PERF-EXPERIMENT] Add second span to a span

cc #95580

Author: bors

compiler/rustc_metadata/src/rmeta/decoder.rs

@@ -632,7 +632,7 @@ impl<'a, 'tcx> Decodable<DecodeContext<'a, 'tcx>> for SpanData {
         let hi = hi + source_file.translated_source_file.start_pos;
 
         // Do not try to decode parent for foreign spans.
-        SpanData { lo, hi, ctxt, parent: None }
+        SpanData { lo, hi, ctxt, parent: None, span2: DUMMY_SP }
     }
 }
 

compiler/rustc_span/src/lib.rs

@@ -440,6 +440,7 @@ pub struct SpanData {
     /// code was created by a macro expansion.
     pub ctxt: SyntaxContext,
     pub parent: Option<LocalDefId>,
+    pub span2: Span,
 }
 
 // Order spans by position in the file.
@@ -452,6 +453,7 @@ impl Ord for SpanData {
             // `LocalDefId` does not implement `Ord`.
             // The other fields are enough to determine in-file order.
             parent: _,
+            span2: _,
         } = self;
         let SpanData {
             lo: o_lo,
@@ -460,6 +462,7 @@ impl Ord for SpanData {
             // `LocalDefId` does not implement `Ord`.
             // The other fields are enough to determine in-file order.
             parent: _,
+            span2: _,
         } = other;
 
         (s_lo, s_hi, s_ctxt).cmp(&(o_lo, o_hi, o_ctxt))

compiler/rustc_span/src/span_encoding.rs

@@ -132,8 +132,9 @@ impl Span {
         }
 
         // Partially-interned or fully-interned format.
-        let index =
-            with_span_interner(|interner| interner.intern(&SpanData { lo, hi, ctxt, parent }));
+        let index = with_span_interner(|interner| {
+            interner.intern(&SpanData { lo, hi, ctxt, parent, span2: DUMMY_SP })
+        });
         let ctxt_or_parent_or_marker = if ctxt2 <= MAX_CTXT {
             ctxt2 as u16 // partially-interned
         } else {
@@ -169,6 +170,7 @@ impl Span {
                     hi: BytePos(self.lo_or_index + len),
                     ctxt: SyntaxContext::from_u32(self.ctxt_or_parent_or_marker as u32),
                     parent: None,
+                    span2: DUMMY_SP,
                 }
             } else {
                 // Inline-parent format.
@@ -182,6 +184,7 @@ impl Span {
                     hi: BytePos(self.lo_or_index + len),
                     ctxt: SyntaxContext::root(),
                     parent: Some(parent),
+                    span2: DUMMY_SP,
                 }
             }
         } else {