From ad7211df6f257e39da2e5a11b2456b4488f32a1e Mon Sep 17 00:00:00 2001
From: Oliver Bruns <obruns@gmail.com>
Date: Mon, 6 Apr 2020 10:38:30 +0200
Subject: [PATCH] [clang] fix undefined behaviour in
RawComment::getFormattedText()
Summary:
Calling `back()` and `pop_back()` on the empty string is undefined
behavior [1,2].
The issue manifested itself as an uncaught `std::out_of_range` exception
when running `clangd` compiled on RHEL7 using devtoolset-9.
[1] https://en.cppreference.com/w/cpp/string/basic_string/back
[2] https://en.cppreference.com/w/cpp/string/basic_string/pop_back
Fixes: 1ff7c32fc91c607b690d4bb9cf42f406be8dde68
Reviewers: teemperor, ioeric, cfe-commits
Reviewed By: teemperor
Subscribers: ilya-biryukov, kadircet, usaxena95
Tags: #clang
Differential Revision: https://reviews.llvm.org/D77468
---
clang/lib/AST/RawCommentList.cpp | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/clang/lib/AST/RawCommentList.cpp b/clang/lib/AST/RawCommentList.cpp
index 8552b4fcd2b..a8d15036cab 100644
--- a/clang/lib/AST/RawCommentList.cpp
+++ b/clang/lib/AST/RawCommentList.cpp
@@ -431,7 +431,7 @@ std::string RawComment::getFormattedText(const SourceManager &SourceMgr,
};
auto DropTrailingNewLines = [](std::string &Str) {
- while (Str.back() == '\n')
+ while (!Str.empty() && Str.back() == '\n')
Str.pop_back();
};
--
2.25.2