From e354cca69629045fe678918757ce036cea2be4f1 Mon Sep 17 00:00:00 2001
From: Rich Kadel <richkadel@google.com>
Date: Sun, 9 May 2021 23:08:31 -0700
Subject: [PATCH] Spanview needs the relevant body_span used for coverage

The coverage body_span doesn't always match the function body_span.
---
 compiler/rustc_mir/src/transform/coverage/debug.rs |  4 +++-
 compiler/rustc_mir/src/transform/coverage/mod.rs   |  1 +
 compiler/rustc_mir/src/util/spanview.rs            | 14 +++++++-------
 3 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/compiler/rustc_mir/src/transform/coverage/debug.rs b/compiler/rustc_mir/src/transform/coverage/debug.rs
index 48361483099f..2397d627880f 100644
--- a/compiler/rustc_mir/src/transform/coverage/debug.rs
+++ b/compiler/rustc_mir/src/transform/coverage/debug.rs
@@ -120,6 +120,7 @@ use rustc_index::vec::Idx;
 use rustc_middle::mir::coverage::*;
 use rustc_middle::mir::{self, BasicBlock, TerminatorKind};
 use rustc_middle::ty::TyCtxt;
+use rustc_span::Span;
 
 use std::iter;
 use std::lazy::SyncOnceCell;
@@ -636,6 +637,7 @@ pub(super) fn dump_coverage_spanview(
     mir_body: &mir::Body<'tcx>,
     basic_coverage_blocks: &CoverageGraph,
     pass_name: &str,
+    body_span: Span,
     coverage_spans: &Vec<CoverageSpan>,
 ) {
     let mir_source = mir_body.source;
@@ -647,7 +649,7 @@ pub(super) fn dump_coverage_spanview(
     let crate_name = tcx.crate_name(def_id.krate);
     let item_name = tcx.def_path(def_id).to_filename_friendly_no_crate();
     let title = format!("{}.{} - Coverage Spans", crate_name, item_name);
-    spanview::write_document(tcx, def_id, span_viewables, &title, &mut file)
+    spanview::write_document(tcx, body_span, span_viewables, &title, &mut file)
         .expect("Unexpected IO error dumping coverage spans as HTML");
 }
 
diff --git a/compiler/rustc_mir/src/transform/coverage/mod.rs b/compiler/rustc_mir/src/transform/coverage/mod.rs
index 918d6ee4b0cc..c15056575c89 100644
--- a/compiler/rustc_mir/src/transform/coverage/mod.rs
+++ b/compiler/rustc_mir/src/transform/coverage/mod.rs
@@ -204,6 +204,7 @@ impl<'a, 'tcx> Instrumentor<'a, 'tcx> {
                 self.mir_body,
                 &self.basic_coverage_blocks,
                 self.pass_name,
+                body_span,
                 &coverage_spans,
             );
         }
diff --git a/compiler/rustc_mir/src/util/spanview.rs b/compiler/rustc_mir/src/util/spanview.rs
index 2103f2f09340..42683dac426e 100644
--- a/compiler/rustc_mir/src/util/spanview.rs
+++ b/compiler/rustc_mir/src/util/spanview.rs
@@ -131,7 +131,7 @@ where
             }
         }
     }
-    write_document(tcx, def_id, span_viewables, title, w)?;
+    write_document(tcx, fn_span(tcx, def_id), span_viewables, title, w)?;
     Ok(())
 }
 
@@ -139,7 +139,7 @@ where
 /// list `SpanViewable`s.
 pub fn write_document<'tcx, W>(
     tcx: TyCtxt<'tcx>,
-    def_id: DefId,
+    spanview_span: Span,
     mut span_viewables: Vec<SpanViewable>,
     title: &str,
     w: &mut W,
@@ -147,16 +147,16 @@ pub fn write_document<'tcx, W>(
 where
     W: Write,
 {
-    let fn_span = fn_span(tcx, def_id);
-    let mut from_pos = fn_span.lo();
-    let end_pos = fn_span.hi();
+    let mut from_pos = spanview_span.lo();
+    let end_pos = spanview_span.hi();
     let source_map = tcx.sess.source_map();
     let start = source_map.lookup_char_pos(from_pos);
     let indent_to_initial_start_col = " ".repeat(start.col.to_usize());
     debug!(
-        "fn_span source is:\n{}{}",
+        "spanview_span={:?}; source is:\n{}{}",
+        spanview_span,
         indent_to_initial_start_col,
-        source_map.span_to_snippet(fn_span).expect("function should have printable source")
+        source_map.span_to_snippet(spanview_span).expect("function should have printable source")
     );
     writeln!(w, "{}", HEADER)?;
     writeln!(w, "<title>{}</title>", title)?;