From b521c7779f7a4441657fbfba5e03c4125db4699b Mon Sep 17 00:00:00 2001
From: Alex Crichton <alex@alexcrichton.com>
Date: Fri, 9 Feb 2018 06:54:32 -0800
Subject: [PATCH] Forcibly disable optimizations in backtrace-debuginfo

Various versions of LLVM do various things with debuginfo but we're most curious
that our own code is working so let's just disable optimizations in this test to
ensure we have as much pristine debuginfo as possible.
---
 src/test/run-pass/backtrace-debuginfo.rs | 34 +++++++++++++++++++-----
 1 file changed, 28 insertions(+), 6 deletions(-)

diff --git a/src/test/run-pass/backtrace-debuginfo.rs b/src/test/run-pass/backtrace-debuginfo.rs
index e8b5f3490e50e..2b82a8943636e 100644
--- a/src/test/run-pass/backtrace-debuginfo.rs
+++ b/src/test/run-pass/backtrace-debuginfo.rs
@@ -15,11 +15,14 @@
 // Unfortunately, LLVM has no "disable" option for this, so we have to set
 // "enable" to 0 instead.
 
-// compile-flags:-g -Cllvm-args=-enable-tail-merge=0
+// compile-flags:-g -Cllvm-args=-enable-tail-merge=0 -Cllvm-args=-opt-bisect-limit=0
 // ignore-pretty issue #37195
 // ignore-cloudabi spawning processes is not supported
 // ignore-emscripten spawning processes is not supported
 
+// note that above `-opt-bisect-limit=0` is used to basically disable
+// optimizations
+
 use std::env;
 
 #[path = "backtrace-debuginfo-aux.rs"] mod aux;
@@ -114,18 +117,26 @@ fn outer(mut counter: i32, main_pos: Pos) {
     inner_inlined(&mut counter, main_pos, pos!());
 }
 
-fn check_trace(output: &str, error: &str) {
+fn check_trace(output: &str, error: &str) -> Result<(), String> {
     // reverse the position list so we can start with the last item (which was the first line)
     let mut remaining: Vec<&str> = output.lines().map(|s| s.trim()).rev().collect();
 
-    assert!(error.contains("stack backtrace"), "no backtrace in the error: {}", error);
+    if !error.contains("stack backtrace") {
+        return Err(format!("no backtrace found in stderr:\n{}", error))
+    }
     for line in error.lines() {
         if !remaining.is_empty() && line.contains(remaining.last().unwrap()) {
             remaining.pop();
         }
     }
-    assert!(remaining.is_empty(),
-            "trace does not match position list: {}\n---\n{}", error, output);
+    if !remaining.is_empty() {
+        return Err(format!("trace does not match position list\n\
+            still need to find {:?}\n\n\
+            --- stdout\n{}\n\
+            --- stderr\n{}",
+            remaining, output, error))
+    }
+    Ok(())
 }
 
 fn run_test(me: &str) {
@@ -133,6 +144,7 @@ fn run_test(me: &str) {
     use std::process::Command;
 
     let mut i = 0;
+    let mut errors = Vec::new();
     loop {
         let out = Command::new(me)
                           .env("RUST_BACKTRACE", "full")
@@ -143,10 +155,20 @@ fn run_test(me: &str) {
             assert!(output.contains("done."), "bad output for successful run: {}", output);
             break;
         } else {
-            check_trace(output, error);
+            if let Err(e) = check_trace(output, error) {
+                errors.push(e);
+            }
         }
         i += 1;
     }
+    if errors.len() > 0 {
+        for error in errors {
+            println!("---------------------------------------");
+            println!("{}", error);
+        }
+
+        panic!("found some errors");
+    }
 }
 
 #[inline(never)]