src/common/Assert.h

// Copyright 2017 The NXT Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#ifndef COMMON_ASSERT_H_
#define COMMON_ASSERT_H_

#include "common/Compiler.h"

void HandleAssertionFailure(const char* file, const char* function, int line, const char* condition);

/*
 * NXT asserts to be used instead of the regular C stdlib assert function (if you don't
 * use assert yet, you should start now!). In debug ASSERT(condition) will trigger an error,
 * otherwise in release it does nothing at runtime.
 *
 * In case of name clashes (with for example a testing library), you can define the
 * NXT_SKIP_ASSERT_SHORTHANDS to only define the NXT_ prefixed macros.
 *
 * These asserts feature:
 *     - Logging of the error with file, line and function information.
 *     - Breaking in the debugger when an assert is triggered and a debugger is attached.
 *     - Use the assert information to help the compiler optimizer in release builds.
 */

// MSVC triggers a warning in /W4 for do {} while(0). SDL worked around this by using
// // (0,0) and points out that it looks like an owl face.
#if defined(NXT_COMPILER_MSVC)
    #define NXT_ASSERT_LOOP_CONDITION (0,0)
#else
    #define NXT_ASSERT_LOOP_CONDITION (0)
#endif

// NXT_ASSERT_CALLSITE_HELPER generates the actual assert code. In Debug it does what you would
// expect of an assert and in release it tries to give hints to make the compiler generate better code.
#if defined(NXT_ENABLE_ASSERTS)
    #define NXT_ASSERT_CALLSITE_HELPER(file, func, line, condition) \
        do { \
            if (!(condition)) { \
                HandleAssertionFailure(file, func, line, #condition); \
            } \
        } while(NXT_ASSERT_LOOP_CONDITION)
#else
    #if defined(NXT_COMPILER_MSVC)
        #define NXT_ASSERT_CALLSITE_HELPER(file, func, line, condition) \
                __assume(condition)
    #elif defined(NXT_COMPILER_CLANG) && defined(__builtin_assume)
        #define NXT_ASSERT_CALLSITE_HELPER(file, func, line, condition) \
                __builtin_assume(condition)
    #else
        #define NXT_ASSERT_CALLSITE_HELPER(file, func, line, condition) \
            do { \
                (void) sizeof(condition); \
            } while(NXT_ASSERT_LOOP_CONDITION)
    #endif
#endif

#define NXT_ASSERT(condition) NXT_ASSERT_CALLSITE_HELPER(__FILE__, __func__, __LINE__, condition)
#define NXT_UNREACHABLE() \
    do { \
        NXT_ASSERT(NXT_ASSERT_LOOP_CONDITION && "Unreachable code hit"); NXT_BUILTIN_UNREACHABLE(); \
    } while(NXT_ASSERT_LOOP_CONDITION)

#if !defined(NXT_SKIP_ASSERT_SHORTHANDS)
    #define ASSERT NXT_ASSERT
    #define UNREACHABLE NXT_UNREACHABLE
#endif

#endif // COMMON_ASSERT_H_