C++ 独立功能

Question

我可以在 C++ 独立环境中使用哪些功能？我正在开发一个小内核(为了我自己的乐趣)，我知道我不能使用整个 stdlib 库，但还有什么？当我尝试使用 new 和 delete 运算符时，它编译时没有遇到任何问题，但链接器说

undefined reference to `operator new[](unsigned long)
undefined reference to `operator delete[](void*)'

我链接了 -lgcc 和 -lsupc++ 选项。我知道异常处理在独立模式下是禁用的，但我有点惊讶 new 和 delete 也是。那么我可以使用什么，不可以使用什么？

Answer 1

What are the features that I can use in c++ freestanding environment?

许多独立的实现是实现定义的:

[intro.compliance] ... A freestanding implementation is one in which execution may take place without the benefit of an operating system, and has an implementation-defined set of libraries that includes certain language-support libraries

[intro.multithread] ... Under a freestanding implementation, it is implementation-defined whether a program can have more than one thread of execution.

[basic.start.main] It is implementation-defined whether a program in a freestanding environment is required to define a main function. [ Note: In a freestanding environment, start-up and termination is implementation-defined; start- up contains the execution of constructors for objects of namespace scope with static storage duration; termination contains the execution of destructors for objects with static storage duration. — end note ]

[using.headers] C ++ headers for freestanding implementations

<ciso646>
<cstddef>
<cfloat>
<limits>
<climits>
<cstdint>
<cstdlib>
<new>
<typeinfo>
<exception>
<initializer_list>
<cstdalign>
<cstdarg>
<cstdbool>
<atomic>

[compliance] The supplied version of the header <cstdlib> shall declare at least the functions abort, atexit, at_quick_- exit, exit, and quick_exit (18.5). The other headers listed in this table shall meet the same requirements as for a hosted implementation.

请注意 malloc/free未在<cstdlib>的所需功能中列出.

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就您的链接器错误而言，既不需要独立实现也不需要托管实现来提供这些重载:

[replacement.functions] A C ++ program may provide the definition for any of twelve dynamic memory allocation function signatures declared in header <new>

在实践中，由于独立环境不能依赖于操作系统，并且 malloc通常使用操作系统提供的功能来实现，在独立环境中不太可能有免费的存储内存管理功能。相反，托管环境需要自由存储内存管理来实现标准库的功能。