Avoid undefined behavior in signed integer negation. Patch by Ahmed Charles.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@141905 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Support/raw_ostream.cpp b/lib/Support/raw_ostream.cpp
index c9cf249500d62064ca816bac2467205f0a93928e..4927e9a7b9d46a8bbded38eecbd3262aea51ffb0 100644 (file)
--- a/lib/Support/raw_ostream.cpp
+++ b/lib/Support/raw_ostream.cpp
@@ -121,7 +121,8 @@ raw_ostream &raw_ostream::operator<<(unsigned long N) {
 raw_ostream &raw_ostream::operator<<(long N) {
   if (N <  0) {
     *this << '-';
-    N = -N;
+    // Avoid undefined behavior on LONG_MIN with a cast.
+    N = -(unsigned long)N;
   }
 
   return this->operator<<(static_cast<unsigned long>(N));