Q_ASSERT 发布构建语义 [英] Q_ASSERT release build semantics

问题描述

我找不到关于发布版本下 Q_ASSERT 语义的明确声明.如果没有断言检查，那么是否对断言表达式进行了评估?

I can't find a clear statement on the semantics of Q_ASSERT under release builds. If there is no assertion checking, then is the asserted expression evaluated at all?

考虑下面的代码

Q_ASSERT(do_something_report_false_if_failed());

do_something_report_false_if_failed() 会在所有潜在的 Qt 构建配置下运行吗?改为这样做是否更安全(即使更冗长且可读性更差):

Will do_something_report_false_if_failed() run under all potential Qt build configurations? Would it be safer (even though a bit more verbose and less readable) to do this instead:

bool is_ok = do_something_report_false_if_failed();
Q_ASSERT(is_ok)

后一种方法的缺点是 ASSERT 失败不那么冗长，但也许它更清楚地表明语句已执行?

The latter approach has the downside that ASSERT failures are less verbose, but perhaps it shows more clearly that the statement is executed?

推荐答案

Q_ASSERT 中的表达式将不在非调试构建配置中进行评估.

The expression inside the Q_ASSERT will not be evaluated in non-debug build configurations.

考虑以下来自 Qt 存储库.

#if !defined(Q_ASSERT)
#  ifndef QT_NO_DEBUG
#    define Q_ASSERT(cond) ((!(cond)) ? qt_assert(#cond,__FILE__,__LINE__) : qt_noop())
#  else
#    define Q_ASSERT(cond) qt_noop()    
#  endif    
#endif

如果定义了 QT_NO_DEBUG，则整个 Q_ASSERT 语句将替换为 qt_noop()，从而删除它之前包含的任何表达式.

If QT_NO_DEBUG is defined, then the entire Q_ASSERT statement is replaced with a qt_noop(), thereby removing any expression that it previously contained.

永远不要依赖 Q_ASSERT 语句中的表达式产生的任何副作用.从技术上讲，仍然可以确保 QT_NO_DEBUG 未在特定构建配置中定义，但这不是一个好主意™.

Never rely on any side effects created by an expression inside a Q_ASSERT statement. Technically it is still possible to ensure that QT_NO_DEBUG is not defined in a specific build configuration, but this is not a Good Idea™.

这篇关于Q_ASSERT 发布构建语义的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！