Make raw_null_ostream flush its buffer in its destructor, so that

it conforms to the assertion added in r77245. This fixes a failure
in qa_override.c in clang's testsuite.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@77255 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Support/raw_ostream.h

@@ -420,6 +420,7 @@ class raw_null_ostream : public raw_ostream {
 
 public:
   explicit raw_null_ostream() {}
+  ~raw_null_ostream();
 };
 
 } // end llvm namespace

lib/Support/raw_ostream.cpp

@@ -438,6 +438,15 @@ uint64_t raw_svector_ostream::tell() {
 //  raw_null_ostream
 //===----------------------------------------------------------------------===//
 
+raw_null_ostream::~raw_null_ostream() {
+#ifndef NDEBUG
+  // ~raw_ostream asserts that the buffer is empty. This isn't necessary
+  // with raw_null_ostream, but it's better to have raw_null_ostream follow
+  // the rules than to change the rules just for raw_null_ostream.
+  flush();
+#endif
+}
+
 void raw_null_ostream::write_impl(const char *Ptr, size_t Size) {
 }