探索GCC 4.9编译器用户指南

需积分: 10 131 浏览量更新于2024-07-22 收藏 3.33MB PDF 举报

"GCC 4.9用户手册是一份详尽的文档，专为用户提供GCC 4.9版本的详细介绍。它由Richard Stallman和GCC开发者社区共同编撰，由GNUPress出版，是学习和理解GNU Compiler Collection (GCC) 4.9的理想资源。此手册发布于2003年10月，主要针对GCC 3.3.1版本，每本印刷版售价为45美元。这份手册覆盖了GCC的核心概念、安装、配置、编译器选项、优化技巧、以及与C/C++、Objective-C、Fortran等编程语言相关的指导。它不仅介绍了如何使用GCC进行源代码编译，还深入探讨了其内部工作原理和高级特性。对于软件开发人员而言，它不仅是一本实用的工具指南，也是理解自由软件理念和遵循GNU通用公共许可证（GPL）的重要参考资料。版权方面，手册受GNU Free Documentation License Version 1.3或更高版本的保护，允许用户在遵循特定条款下自由复制、分发和修改文档，其中特别强调了对自由软件的支持，以及前后封面的授权声明。前封面文字为"一个GNU手册"，后封面则指出读者可以像使用GNU软件一样自由地处理这本手册。无论是初次接触GCC的新手还是经验丰富的开发者，这份用户手册都是深入掌握和优化GCC 4.9的关键资源，提供了全面的学习路径和实践指导。通过阅读和理解这份手册，用户能够提升编程效率，同时也支持并践行开源社区的精神。"

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=c90’ 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 31.

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 substantially complete support for this standard

version; see http://gcc.gnu.org/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.

A fourth version of the C standard, known as C11, was published in 2011 as ISO/IEC

9899:2011. GCC has substantially complete support for this standard, enabled with

‘-std=c11’ or ‘-std=iso9899:2011’. (While in development, drafts of this standard

version were referred to as C1X.)

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

ﬂict with the C standard. See Chapter 6 [Extensions to the C Language Family], page 349.

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=gnu90’ (for C90 with GNU extensions), ‘-std=gnu99’ (for C99 with

GNU extensions) or ‘-std=gnu11’ (for C11 with GNU extensions). The default, if no C lan-

guage dialect options are given, is ‘-std=gnu90’; this is intended to change to ‘-std=gnu11’

in some future release. Some features that are part of the C99 standard are accepted as

6 Using the GNU Compiler Collection (GCC)

extensions in C90 mode, and some features that are part of the C11 standard are accepted

as extensions in C90 and C99 modes.

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,

also those in <iso646.h>; since C99, also those in <stdbool.h> and <stdint.h>; and since

C11, also those in <stdalign.h> and <stdnoreturn.h>. In addition, 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 31.

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

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

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

in the GNU C library). See Section 11.5 [Standard Libraries], page 750.

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 original ISO C++ standard (1998) and contains experimental support for

the second ISO C++ standard (2011).

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’, ‘-std=c++98’, or ‘-std=c++03’; to

剩余855页未读，继续阅读

mkmkbird

粉丝: 1
资源: 7

探索GCC 4.9编译器用户指南

gcc 4.9

metasploit中文手册

omnet++4.0用户手册

gnu make使用手册（中译版）

GNU Make 使用手册（中译版）

NUC970 BSP使用手册简体中文版小部分有点字体间距问题

Makefile中文手册

Makefile V3.8手册

GDB英文官方手册

MongoDB分片集群搭建教程：副本集创建与数据分片

最新资源