Prevent __rust_begin_short_backtrace frames from being tail-call op…

…timised away
rust-lang · Aug 2, 2020 · cd53efc · cd53efc
1 parent 1e99138
commit cd53efc
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Showing 2 changed files with 10 additions and 2 deletions.
diff --git a/library/std/src/sys_common/backtrace.rs b/library/std/src/sys_common/backtrace.rs
@@ -126,7 +126,12 @@ where
     F: Send,
     T: Send,
 {
-    f()
+    let result = f();
+
+    // prevent this frame from being tail-call optimised away
+    crate::hint::black_box(());
+
+    result
 }
 
 pub enum RustBacktrace {

diff --git a/library/test/src/lib.rs b/library/test/src/lib.rs
@@ -514,7 +514,10 @@ pub fn run_test(
 /// Fixed frame used to clean the backtrace with `RUST_BACKTRACE=1`.
 #[inline(never)]
 fn __rust_begin_short_backtrace<F: FnOnce()>(f: F) {
-    f()
+    f();
+
+    // prevent this frame from being tail-call optimised away
+    black_box(());
 }
 
 fn run_test_in_process(