Adding upstream version 1:7.0.4.upstream/1%7.0.4upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 39 insertions, 0 deletions

diff --git a/include/o3tl/unreachable.hxx b/include/o3tl/unreachable.hxx
new file mode 100644
index 000000000..bc33d34b5
--- /dev/null
+++ b/include/o3tl/unreachable.hxx
@@ -0,0 +1,39 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4; fill-column: 100 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+#ifndef INCLUDED_O3TL_UNREACHABLE_HXX
+#define INCLUDED_O3TL_UNREACHABLE_HXX
+
+#include <sal/config.h>
+
+#include <cassert>
+
+// A better replacement for assert(false) to indicate a place in the code that should not be
+// reachable.  This should improve on the sometimes poor false-positive warnings emitted by
+// compilers when they cannot detect that some condition flagged by assert(false) cannot occur,
+// either because assert is reduced to a no-op by NDEBUG or because assert is not marked as noreturn
+// in the MSVC headers.  This is inspired by LLVM's LLVM_BUILTIN_UNREACHABLE
+// (llvm/include/llvm/Support/Compiler.h).
+
+#if defined _MSC_VER
+#define O3TL_UNREACHABLE_detail __assume(false)
+#else // assuming Clang or GCC with support for:
+#define O3TL_UNREACHABLE_detail __builtin_unreachable()
+#endif
+
+#define O3TL_UNREACHABLE                                                                           \
+    do                                                                                             \
+    {                                                                                              \
+        assert(false);                                                                             \
+        O3TL_UNREACHABLE_detail;                                                                   \
+    } while (false)
+
+#endif
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */