From 8e8828259ac1433dd3981fcec9670d7394c2ade5 Mon Sep 17 00:00:00 2001
From: Aaron Hill <aa1ronham@gmail.com>
Date: Mon, 5 Oct 2020 17:29:55 -0400
Subject: [PATCH] Use macro callsite spans in backtrace

This mirrors what we do in the debuginfo used for runtime backtraces.
---
 src/shims/backtrace.rs              | 8 +++++++-
 tests/run-pass/backtrace-api.rs     | 8 +++++++-
 tests/run-pass/backtrace-api.stderr | 5 +++--
 tests/run-pass/backtrace-api.stdout | 5 +++--
 4 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/src/shims/backtrace.rs b/src/shims/backtrace.rs
index 75cd61b0f59..bd36587116a 100644
--- a/src/shims/backtrace.rs
+++ b/src/shims/backtrace.rs
@@ -26,7 +26,13 @@ fn handle_miri_get_backtrace(
 
         let mut data = Vec::new();
         for frame in this.active_thread_stack().iter().rev() {
-            data.push((frame.instance, frame.current_span().lo()));
+            let mut span = frame.current_span();
+            // Match the behavior of runtime backtrace spans
+            // by using a non-macro span in our backtrace. See `FunctionCx::debug_loc`.
+            if span.from_expansion() && !tcx.sess.opts.debugging_opts.debug_macros {
+                span = rustc_span::hygiene::walk_chain(span, frame.body.span.ctxt())
+            }
+            data.push((frame.instance, span.lo()));
         }
 
         let ptrs: Vec<_> = data.into_iter().map(|(instance, pos)| {
diff --git a/tests/run-pass/backtrace-api.rs b/tests/run-pass/backtrace-api.rs
index 80e64c2e1c8..eaf29abfd9f 100644
--- a/tests/run-pass/backtrace-api.rs
+++ b/tests/run-pass/backtrace-api.rs
@@ -18,7 +18,13 @@ struct MiriFrame {
 
 #[inline(never)] fn func_a() -> Box<[*mut ()]> { func_b::<u8>() }
 #[inline(never)] fn func_b<T>() -> Box<[*mut ()]> { func_c() }
-#[inline(never)] fn func_c() -> Box<[*mut ()]> { unsafe { miri_get_backtrace(0) } }
+
+macro_rules! invoke_func_d {
+    () => { func_d() }
+}
+
+#[inline(never)] fn func_c() -> Box<[*mut ()]> { invoke_func_d!() }
+#[inline(never)] fn func_d() -> Box<[*mut ()]> { unsafe { miri_get_backtrace(0) } }
 
 fn main() {
     let mut seen_main = false;
diff --git a/tests/run-pass/backtrace-api.stderr b/tests/run-pass/backtrace-api.stderr
index 15851a1cc72..02e7a7e1eaf 100644
--- a/tests/run-pass/backtrace-api.stderr
+++ b/tests/run-pass/backtrace-api.stderr
@@ -1,7 +1,8 @@
-$DIR/backtrace-api.rs:21:59 (func_c)
+$DIR/backtrace-api.rs:27:59 (func_d)
+$DIR/backtrace-api.rs:26:50 (func_c)
 $DIR/backtrace-api.rs:20:53 (func_b)
 $DIR/backtrace-api.rs:19:50 (func_a)
-$DIR/backtrace-api.rs:25:18 (main)
+$DIR/backtrace-api.rs:31:18 (main)
 RUSTLIB/core/src/ops/function.rs:LL:COL (<fn() as std::ops::FnOnce<()>>::call_once - shim(fn()))
 RUSTLIB/std/src/sys_common/backtrace.rs:LL:COL (std::sys_common::backtrace::__rust_begin_short_backtrace)
 RUSTLIB/std/src/rt.rs:LL:COL (std::rt::lang_start::{closure#0})
diff --git a/tests/run-pass/backtrace-api.stdout b/tests/run-pass/backtrace-api.stdout
index 453cf0b774a..90ab4bb96e6 100644
--- a/tests/run-pass/backtrace-api.stdout
+++ b/tests/run-pass/backtrace-api.stdout
@@ -1,4 +1,5 @@
-$DIR/backtrace-api.rs:21:59 (func_c)
+$DIR/backtrace-api.rs:27:59 (func_d)
+$DIR/backtrace-api.rs:26:50 (func_c)
 $DIR/backtrace-api.rs:20:53 (func_b::<u8>)
 $DIR/backtrace-api.rs:19:50 (func_a)
-$DIR/backtrace-api.rs:25:18 (main)
+$DIR/backtrace-api.rs:31:18 (main)
-- 
2.44.0