LibreOffice Module o3tl (master)  1
unreachable.hxx
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1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4; fill-column: 100 -*- */
2 /*
3  * This file is part of the LibreOffice project.
4  *
5  * This Source Code Form is subject to the terms of the Mozilla Public
6  * License, v. 2.0. If a copy of the MPL was not distributed with this
7  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
8  */
9 
10 #ifndef INCLUDED_O3TL_UNREACHABLE_HXX
11 #define INCLUDED_O3TL_UNREACHABLE_HXX
12 
13 #include <sal/config.h>
14 
15 #include <cassert>
16 
17 // A better replacement for assert(false) to indicate a place in the code that should not be
18 // reachable. This should improve on the sometimes poor false-positive warnings emitted by
19 // compilers when they cannot detect that some condition flagged by assert(false) cannot occur,
20 // either because assert is reduced to a no-op by NDEBUG or because assert is not marked as noreturn
21 // in the MSVC headers. This is inspired by LLVM's LLVM_BUILTIN_UNREACHABLE
22 // (llvm/include/llvm/Support/Compiler.h).
23 
24 #if defined _MSC_VER
25 #define O3TL_UNREACHABLE_detail __assume(false)
26 #else // assuming Clang or GCC with support for:
27 #define O3TL_UNREACHABLE_detail __builtin_unreachable()
28 #endif
29 
30 #define O3TL_UNREACHABLE \
31  do \
32  { \
33  assert(false); \
34  O3TL_UNREACHABLE_detail; \
35  } while (false)
36 
37 #endif
38 
39 /* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */