GNU Compiler 4.4.1详解：Stallman与社区的贡献

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本资源是关于使用GNU Compiler（GNU Compiler Collection，简称GCC）的一份指南，特别针对的是GCC 4.4.1版本，即Sourcery G++ Lite 2010 Q1-188。该指南由Richard Stallman 和 GCC 开发者社区共同编写，由GNUPress出版，隶属于GNU Free Software Foundation。此版本的出版日期为2003年10月，适用于GCC 3.3.1。《Using the GNU Compiler》这本书深入讲解了GCC的核心功能和使用方法，包括编译器的基本原理、语法特性、选项设置以及与C/C++语言相关的优化技巧。作为一款开源的编译器，GCC在软件开发中扮演着重要角色，其版本更新反映了技术的进步和开发者社区的不断努力。书中涵盖了以下关键知识点： 1. **GNU Compiler Collection (GCC)**：这是GNU项目的一部分，提供了一个全面的C、C++、Objective-C等编程语言的编译器套件。它不仅支持标准语言特性和特性扩展，还提供了丰富的错误检测和警告系统，有助于提高代码质量。 2. **版本4.4.1**：介绍了这一特定版本的特性，可能包括新的优化算法、支持的平台兼容性增强，以及对特定语言特性的支持，如C++11标准的初步实现。 3. **Sourcery G++ Lite**：这是一个针对嵌入式和小型设备优化的GCC版本，强调代码大小和性能的高效性，适合资源受限环境。 4. **Richard Stallman和开发者社区**：本书作者Richard Stallman是GNU项目的创始人，他的理念和贡献对于理解GCC背后的思想至关重要。开发者社区的参与确保了GCC的持续改进和适应技术发展。 5. **版权与授权**：书中内容遵循GNU Free Documentation License (FDL)，这是一种自由文档许可证，允许用户复制、分发和修改文档，体现了自由软件的精神。 6. **学习资源**：提供了联系方式（如印刷版购买信息和电子邮箱），以及免费文档许可的具体条款，如封面文本和后封文本，强调了软件自由的重要性。阅读这份指南，开发者可以深入了解如何充分利用GCC进行高效、合规的编程，无论是用于个人学习还是在实际项目中，都能从中获益匪浅。同时，对于GNU项目和开源软件的理解也会有所加深。

Chapter 2: Language Standards Supported by GCC 5

2 Language Standards Supported by GCC

For each language compiled by GCC for which there is a standard, GCC attempts to follow

one or more versions of that standard, possibly with some exceptions, and possibly with

some extensions.

2.1 C language

GCC supports three versions of the C standard, although support for the most recent version

is not yet complete.

The original ANSI C standard (X3.159-1989) was ratiﬁed in 1989 and published in 1990.

This standard was ratiﬁed as an ISO standard (ISO/IEC 9899:1990) later in 1990. There

were no technical diﬀerences between these publications, although the sections of the ANSI

standard were renumbered and became clauses in the ISO standard. This standard, in

both its forms, is commonly known as C89, or occasionally as C90, from the dates of

ratiﬁcation. The ANSI standard, but not the ISO standard, also came with a Rationale

document. To select this standard in GCC, use one of the options ‘-ansi’, ‘-std=c89’ or

‘-std=iso9899:1990’; to obtain all the diagnostics required by the standard, you should

also specify ‘-pedantic’ (or ‘-pedantic-errors’ if you want them to be errors rather than

warnings). See Section 3.4 [Options Controlling C Dialect], page 27.

Errors in the 1990 ISO C standard were corrected in two Technical Corrigenda published

in 1994 and 1996. GCC does not support the uncorrected version.

An amendment to the 1990 standard was published in 1995. This amendment added

digraphs and __STDC_VERSION__ to the language, but otherwise concerned the library. This

amendment is commonly known as AMD1; the amended standard is sometimes known as

C94 or C95. To select this standard in GCC, use the option ‘-std=iso9899:199409’ (with,

as for other standard versions, ‘-pedantic’ to receive all required diagnostics).

A new edition of the ISO C standard was published in 1999 as ISO/IEC 9899:1999, and

is commonly known as C99. GCC has incomplete support for this standard version; see

http://gcc.gnu.org/gcc-4.4/c99status.html for details. To select this standard, use

‘-std=c99’ or ‘-std=iso9899:1999’. (While in development, drafts of this standard version

were referred to as C9X.)

Errors in the 1999 ISO C standard were corrected in three Technical Corrigenda published

in 2001, 2004 and 2007. GCC does not support the uncorrected version.

By default, GCC provides some extensions to the C language that on rare occasions con-

ﬂict with the C standard. See Chapter 5 [Extensions to the C Language Family], page 261.

Use of the ‘-std’ options listed above will disable these extensions where they conﬂict with

the C standard version selected. You may also select an extended version of the C language

explicitly with ‘-std=gnu89’ (for C89 with GNU extensions) or ‘-std=gnu99’ (for C99 with

GNU extensions). The default, if no C language dialect options are given, is ‘-std=gnu89’;

this will change to ‘-std=gnu99’ in some future release when the C99 support is complete.

Some features that are part of the C99 standard are accepted as extensions in C89 mode.

The ISO C standard deﬁnes (in clause 4) two classes of conforming implementation. A

conforming hosted implementation supports the whole standard including all the library fa-

cilities; a conforming freestanding implementation is only required to provide certain library

facilities: those in <float.h>, <limits.h>, <stdarg.h>, and <stddef.h>; since AMD1,

6 Using the GNU Compiler Collection (GCC)

also those in <iso646.h>; and in C99, also those in <stdbool.h> and <stdint.h>. In ad-

dition, complex types, added in C99, are not required for freestanding implementations. The

standard also deﬁnes two environments for programs, a freestanding environment, required

of all implementations and which may not have library facilities beyond those required of

freestanding implementations, where the handling of program startup and termination are

implementation-deﬁned, and a hosted environment, which is not required, in which all the

library facilities are provided and startup is through a function int main (void) or int

main (int, char *[]). An OS kernel would be a freestanding environment; a program

using the facilities of an operating system would normally be in a hosted implementation.

GCC aims towards being usable as a conforming freestanding implementation, or as the

compiler for a conforming hosted implementation. By default, it will act as the compiler for a

hosted implementation, deﬁning __STDC_HOSTED__ as 1 and presuming that when the names

of ISO C functions are used, they have the semantics deﬁned in the standard. To make it act

as a conforming freestanding implementation for a freestanding environment, use the option

‘-ffreestanding’; it will then deﬁne __STDC_HOSTED__ to 0 and not make assumptions

about the meanings of function names from the standard library, with exceptions noted

below. To build an OS kernel, you may well still need to make your own arrangements for

linking and startup. See Section 3.4 [Options Controlling C Dialect], page 27.

GCC does not provide the library facilities required only of hosted implementations, nor

yet all the facilities required by C99 of freestanding implementations; to use the facilities

of a hosted environment, you will need to ﬁnd them elsewhere (for example, in the GNU C

library). See Section 10.6 [Standard Libraries], page 568.

Most of the compiler support routines used by GCC are present in ‘libgcc’, but there

are a few exceptions. GCC requires the freestanding environment provide memcpy, memmove,

memset and memcmp. Finally, if __builtin_trap is used, and the target does not implement

the trap pattern, then GCC will emit a call to abort.

For references to Technical Corrigenda, Rationale documents and information concerning

the history of C that is available online, see http://gcc.gnu.org/readings.html

2.2 C++ language

GCC supports the ISO C++ standard (1998) and contains experimental support for the

upcoming ISO C++ standard (200x).

The original ISO C++ standard was published as the ISO standard (ISO/IEC 14882:1998)

and amended by a Technical Corrigenda published in 2003 (ISO/IEC 14882:2003). These

standards are referred to as C++98 and C++03, respectively. GCC implements the majority

of C++98 (export is a notable exception) and most of the changes in C++03. To select this

standard in GCC, use one of the options ‘-ansi’ or ‘-std=c++98’; to obtain all the diagnos-

tics required by the standard, you should also specify ‘-pedantic’ (or ‘-pedantic-errors’

if you want them to be errors rather than warnings).

The ISO C++ committee is working on a new ISO C++ standard, dubbed C++0x,

that is intended to be published by 2009. C++0x contains several changes to the

C++ language, some of which have been implemented in an experimental C++0x

mode in GCC. The C++0x mode in GCC tracks the draft working paper for the

C++0x standard; the latest working paper is available on the ISO C++ commit-

tee’s web site at http://www.open-std.org/jtc1/sc22/wg21/. For information

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arm-ca9-linux-gnueabihf-6.5

No CMAKE_C_COMPILER could be found.

project error : cannot run target compiler ' aarch64-linux-gnu-g++"

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