From 66b31c509832a1e3daa6880bca097c9a27a9b6b5 Mon Sep 17 00:00:00 2001
From: Hui Xiao <huixiao@fb.com>
Date: Tue, 7 Dec 2021 22:40:43 -0800
Subject: [PATCH] Fix -Werror=maybe-uninitialized in db_stress_tool (#9265)
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Summary:
Context/Summary:
Uninitialized variable `SequenceNumber old_saved_seqno` causes asan related compilation error/warning below:

```
db_stress_tool/expected_state.cc:308:55: error: ‘old_saved_seqno’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
  308 |   if (s.ok() && old_saved_seqno != kMaxSequenceNumber &&
      |       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~
```

Fix it by initializing to 0.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/9265

Test Plan:
- make clean && COMPILE_WITH_ASAN=1 make -j48 db_stress_tool/expected_state.o
- monitor if same error happens again after merging

Reviewed By: ajkr

Differential Revision: D32939630

Pulled By: hx235

fbshipit-source-id: 41697515fd11ada8427f606b5dceb4e58d12cb80
---
 db_stress_tool/expected_state.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/db_stress_tool/expected_state.cc b/db_stress_tool/expected_state.cc
index fb52e818c..b01d8c4ad 100644
--- a/db_stress_tool/expected_state.cc
+++ b/db_stress_tool/expected_state.cc
@@ -273,7 +273,7 @@ Status FileExpectedStateManager::SaveAtAndAfter(DB* db) {
     s = FileSystem::Default()->RenameFile(state_file_temp_path, state_file_path,
                                           IOOptions(), nullptr /* dbg */);
   }
-  SequenceNumber old_saved_seqno;
+  SequenceNumber old_saved_seqno = 0;
   if (s.ok()) {
     old_saved_seqno = saved_seqno_;
     saved_seqno_ = seqno;