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<h1 class="settitle" align="center">Using the GNU Compiler Collection (GCC)</h1>
<p>This file documents the use of the GNU compilers.
</p><br>
<p>Copyright &copy; 1988-2015 Free Software Foundation, Inc.
</p>
<p>Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3 or
any later version published by the Free Software Foundation; with the
Invariant Sections being &ldquo;Funding Free Software&rdquo;, the Front-Cover
Texts being (a) (see below), and with the Back-Cover Texts being (b)
(see below). A copy of the license is included in the section entitled
&ldquo;GNU Free Documentation License&rdquo;.
</p>
<p>(a) The FSF&rsquo;s Front-Cover Text is:
</p>
<p>A GNU Manual
</p>
<p>(b) The FSF&rsquo;s Back-Cover Text is:
</p>
<p>You have freedom to copy and modify this GNU Manual, like GNU
software. Copies published by the Free Software Foundation raise
funds for GNU development.
</p>
<br>
<a name="SEC_Overview"></a>
<h2 class="shortcontents-heading">Short Table of Contents</h2>
<div class="shortcontents">
<ul class="no-bullet">
<li><a name="stoc-Programming-Languages-Supported-by-GCC" href="#toc-Programming-Languages-Supported-by-GCC">1 Programming Languages Supported by GCC</a></li>
<li><a name="stoc-Language-Standards-Supported-by-GCC" href="#toc-Language-Standards-Supported-by-GCC">2 Language Standards Supported by GCC</a></li>
<li><a name="stoc-GCC-Command-Options" href="#toc-GCC-Command-Options">3 GCC Command Options</a></li>
<li><a name="stoc-C-Implementation_002ddefined-behavior" href="#toc-C-Implementation_002ddefined-behavior">4 C Implementation-defined behavior</a></li>
<li><a name="stoc-C_002b_002b-Implementation_002ddefined-behavior" href="#toc-C_002b_002b-Implementation_002ddefined-behavior">5 C++ Implementation-defined behavior</a></li>
<li><a name="stoc-Extensions-to-the-C-Language-Family" href="#toc-Extensions-to-the-C-Language-Family">6 Extensions to the C Language Family</a></li>
<li><a name="stoc-Extensions-to-the-C_002b_002b-Language" href="#toc-Extensions-to-the-C_002b_002b-Language">7 Extensions to the C++ Language</a></li>
<li><a name="stoc-GNU-Objective_002dC-features" href="#toc-GNU-Objective_002dC-features">8 GNU Objective-C features</a></li>
<li><a name="stoc-Binary-Compatibility" href="#toc-Binary-Compatibility">9 Binary Compatibility</a></li>
<li><a name="stoc-gcov_002d_002d_002da-Test-Coverage-Program" href="#toc-gcov_002d_002d_002da-Test-Coverage-Program">10 <code>gcov</code>&mdash;a Test Coverage Program</a></li>
<li><a name="stoc-Known-Causes-of-Trouble-with-GCC" href="#toc-Known-Causes-of-Trouble-with-GCC">11 Known Causes of Trouble with GCC</a></li>
<li><a name="stoc-Reporting-Bugs" href="#toc-Reporting-Bugs">12 Reporting Bugs</a></li>
<li><a name="stoc-How-To-Get-Help-with-GCC" href="#toc-How-To-Get-Help-with-GCC">13 How To Get Help with GCC</a></li>
<li><a name="stoc-Contributing-to-GCC-Development" href="#toc-Contributing-to-GCC-Development">14 Contributing to GCC Development</a></li>
<li><a name="stoc-Funding-Free-Software" href="#toc-Funding-Free-Software">Funding Free Software</a></li>
<li><a name="stoc-The-GNU-Project-and-GNU_002fLinux" href="#toc-The-GNU-Project-and-GNU_002fLinux">The GNU Project and GNU/Linux</a></li>
<li><a name="stoc-GNU-General-Public-License" href="#toc-GNU-General-Public-License">GNU General Public License</a></li>
<li><a name="stoc-GNU-Free-Documentation-License-1" href="#toc-GNU-Free-Documentation-License-1">GNU Free Documentation License</a></li>
<li><a name="stoc-Contributors-to-GCC" href="#toc-Contributors-to-GCC">Contributors to GCC</a></li>
<li><a name="stoc-Option-Index-1" href="#toc-Option-Index-1">Option Index</a></li>
<li><a name="stoc-Keyword-Index-1" href="#toc-Keyword-Index-1">Keyword Index</a></li>
</ul>
</div>
<a name="SEC_Contents"></a>
<h2 class="contents-heading">Table of Contents</h2>
<div class="contents">
<ul class="no-bullet">
<li><a name="toc-Programming-Languages-Supported-by-GCC" href="G_002b_002b-and-GCC.html#G_002b_002b-and-GCC">1 Programming Languages Supported by GCC</a></li>
<li><a name="toc-Language-Standards-Supported-by-GCC" href="Standards.html#Standards">2 Language Standards Supported by GCC</a>
<ul class="no-bullet">
<li><a name="toc-C-language" href="Standards.html#C-language">2.1 C language</a></li>
<li><a name="toc-C_002b_002b-language" href="Standards.html#C_002b_002b-language">2.2 C++ language</a></li>
<li><a name="toc-Objective_002dC-and-Objective_002dC_002b_002b-languages" href="Standards.html#Objective_002dC-and-Objective_002dC_002b_002b-languages">2.3 Objective-C and Objective-C++ languages</a></li>
<li><a name="toc-Go-language" href="Standards.html#Go-language">2.4 Go language</a></li>
<li><a name="toc-References-for-other-languages" href="Standards.html#References-for-other-languages">2.5 References for other languages</a></li>
</ul></li>
<li><a name="toc-GCC-Command-Options" href="Invoking-GCC.html#Invoking-GCC">3 GCC Command Options</a>
<ul class="no-bullet">
<li><a name="toc-Option-Summary-1" href="Option-Summary.html#Option-Summary">3.1 Option Summary</a></li>
<li><a name="toc-Options-Controlling-the-Kind-of-Output" href="Overall-Options.html#Overall-Options">3.2 Options Controlling the Kind of Output</a></li>
<li><a name="toc-Compiling-C_002b_002b-Programs" href="Invoking-G_002b_002b.html#Invoking-G_002b_002b">3.3 Compiling C++ Programs</a></li>
<li><a name="toc-Options-Controlling-C-Dialect" href="C-Dialect-Options.html#C-Dialect-Options">3.4 Options Controlling C Dialect</a></li>
<li><a name="toc-Options-Controlling-C_002b_002b-Dialect" href="C_002b_002b-Dialect-Options.html#C_002b_002b-Dialect-Options">3.5 Options Controlling C++ Dialect</a></li>
<li><a name="toc-Options-Controlling-Objective_002dC-and-Objective_002dC_002b_002b-Dialects" href="Objective_002dC-and-Objective_002dC_002b_002b-Dialect-Options.html#Objective_002dC-and-Objective_002dC_002b_002b-Dialect-Options">3.6 Options Controlling Objective-C and Objective-C++ Dialects</a></li>
<li><a name="toc-Options-to-Control-Diagnostic-Messages-Formatting" href="Language-Independent-Options.html#Language-Independent-Options">3.7 Options to Control Diagnostic Messages Formatting</a></li>
<li><a name="toc-Options-to-Request-or-Suppress-Warnings" href="Warning-Options.html#Warning-Options">3.8 Options to Request or Suppress Warnings</a></li>
<li><a name="toc-Options-for-Debugging-Your-Program-or-GCC" href="Debugging-Options.html#Debugging-Options">3.9 Options for Debugging Your Program or GCC</a></li>
<li><a name="toc-Options-That-Control-Optimization" href="Optimize-Options.html#Optimize-Options">3.10 Options That Control Optimization</a></li>
<li><a name="toc-Options-Controlling-the-Preprocessor" href="Preprocessor-Options.html#Preprocessor-Options">3.11 Options Controlling the Preprocessor</a></li>
<li><a name="toc-Passing-Options-to-the-Assembler" href="Assembler-Options.html#Assembler-Options">3.12 Passing Options to the Assembler</a></li>
<li><a name="toc-Options-for-Linking" href="Link-Options.html#Link-Options">3.13 Options for Linking</a></li>
<li><a name="toc-Options-for-Directory-Search" href="Directory-Options.html#Directory-Options">3.14 Options for Directory Search</a></li>
<li><a name="toc-Specifying-subprocesses-and-the-switches-to-pass-to-them" href="Spec-Files.html#Spec-Files">3.15 Specifying subprocesses and the switches to pass to them</a></li>
<li><a name="toc-Specifying-Target-Machine-and-Compiler-Version" href="Target-Options.html#Target-Options">3.16 Specifying Target Machine and Compiler Version</a></li>
<li><a name="toc-Hardware-Models-and-Configurations" href="Submodel-Options.html#Submodel-Options">3.17 Hardware Models and Configurations</a>
<ul class="no-bullet">
<li><a name="toc-AArch64-Options-1" href="AArch64-Options.html#AArch64-Options">3.17.1 AArch64 Options</a>
<ul class="no-bullet">
<li><a name="toc-_002dmarch-and-_002dmcpu-feature-modifiers" href="AArch64-Options.html#g_t_002dmarch-and-_002dmcpu-feature-modifiers">3.17.1.1 <samp>-march</samp> and <samp>-mcpu</samp> feature modifiers</a></li>
</ul></li>
<li><a name="toc-Adapteva-Epiphany-Options-1" href="Adapteva-Epiphany-Options.html#Adapteva-Epiphany-Options">3.17.2 Adapteva Epiphany Options</a></li>
<li><a name="toc-ARC-Options-1" href="ARC-Options.html#ARC-Options">3.17.3 ARC Options</a></li>
<li><a name="toc-ARM-Options-1" href="ARM-Options.html#ARM-Options">3.17.4 ARM Options</a></li>
<li><a name="toc-AVR-Options-1" href="AVR-Options.html#AVR-Options">3.17.5 AVR Options</a>
<ul class="no-bullet">
<li><a name="toc-EIND-and-Devices-with-more-than-128-Ki-Bytes-of-Flash" href="AVR-Options.html#EIND-and-Devices-with-more-than-128-Ki-Bytes-of-Flash">3.17.5.1 <code>EIND</code> and Devices with more than 128 Ki Bytes of Flash</a></li>
<li><a name="toc-Handling-of-the-RAMPD_002c-RAMPX_002c-RAMPY-and-RAMPZ-Special-Function-Registers" href="AVR-Options.html#Handling-of-the-RAMPD_002c-RAMPX_002c-RAMPY-and-RAMPZ-Special-Function-Registers">3.17.5.2 Handling of the <code>RAMPD</code>, <code>RAMPX</code>, <code>RAMPY</code> and <code>RAMPZ</code> Special Function Registers</a></li>
<li><a name="toc-AVR-Built_002din-Macros" href="AVR-Options.html#AVR-Built_002din-Macros">3.17.5.3 AVR Built-in Macros</a></li>
</ul></li>
<li><a name="toc-Blackfin-Options-1" href="Blackfin-Options.html#Blackfin-Options">3.17.6 Blackfin Options</a></li>
<li><a name="toc-C6X-Options-1" href="C6X-Options.html#C6X-Options">3.17.7 C6X Options</a></li>
<li><a name="toc-CRIS-Options-1" href="CRIS-Options.html#CRIS-Options">3.17.8 CRIS Options</a></li>
<li><a name="toc-CR16-Options-1" href="CR16-Options.html#CR16-Options">3.17.9 CR16 Options</a></li>
<li><a name="toc-Darwin-Options-1" href="Darwin-Options.html#Darwin-Options">3.17.10 Darwin Options</a></li>
<li><a name="toc-DEC-Alpha-Options-1" href="DEC-Alpha-Options.html#DEC-Alpha-Options">3.17.11 DEC Alpha Options</a></li>
<li><a name="toc-FR30-Options-1" href="FR30-Options.html#FR30-Options">3.17.12 FR30 Options</a></li>
<li><a name="toc-FRV-Options-1" href="FRV-Options.html#FRV-Options">3.17.13 FRV Options</a></li>
<li><a name="toc-GNU_002fLinux-Options-1" href="GNU_002fLinux-Options.html#GNU_002fLinux-Options">3.17.14 GNU/Linux Options</a></li>
<li><a name="toc-H8_002f300-Options-1" href="H8_002f300-Options.html#H8_002f300-Options">3.17.15 H8/300 Options</a></li>
<li><a name="toc-HPPA-Options-1" href="HPPA-Options.html#HPPA-Options">3.17.16 HPPA Options</a></li>
<li><a name="toc-Intel-386-and-AMD-x86_002d64-Options" href="i386-and-x86_002d64-Options.html#i386-and-x86_002d64-Options">3.17.17 Intel 386 and AMD x86-64 Options</a></li>
<li><a name="toc-i386-and-x86_002d64-Windows-Options-1" href="i386-and-x86_002d64-Windows-Options.html#i386-and-x86_002d64-Windows-Options">3.17.18 i386 and x86-64 Windows Options</a></li>
<li><a name="toc-IA_002d64-Options-1" href="IA_002d64-Options.html#IA_002d64-Options">3.17.19 IA-64 Options</a></li>
<li><a name="toc-LM32-Options-1" href="LM32-Options.html#LM32-Options">3.17.20 LM32 Options</a></li>
<li><a name="toc-M32C-Options-1" href="M32C-Options.html#M32C-Options">3.17.21 M32C Options</a></li>
<li><a name="toc-M32R_002fD-Options-1" href="M32R_002fD-Options.html#M32R_002fD-Options">3.17.22 M32R/D Options</a></li>
<li><a name="toc-M680x0-Options-1" href="M680x0-Options.html#M680x0-Options">3.17.23 M680x0 Options</a></li>
<li><a name="toc-MCore-Options-1" href="MCore-Options.html#MCore-Options">3.17.24 MCore Options</a></li>
<li><a name="toc-MeP-Options-1" href="MeP-Options.html#MeP-Options">3.17.25 MeP Options</a></li>
<li><a name="toc-MicroBlaze-Options-1" href="MicroBlaze-Options.html#MicroBlaze-Options">3.17.26 MicroBlaze Options</a></li>
<li><a name="toc-MIPS-Options-1" href="MIPS-Options.html#MIPS-Options">3.17.27 MIPS Options</a></li>
<li><a name="toc-MMIX-Options-1" href="MMIX-Options.html#MMIX-Options">3.17.28 MMIX Options</a></li>
<li><a name="toc-MN10300-Options-1" href="MN10300-Options.html#MN10300-Options">3.17.29 MN10300 Options</a></li>
<li><a name="toc-Moxie-Options-1" href="Moxie-Options.html#Moxie-Options">3.17.30 Moxie Options</a></li>
<li><a name="toc-MSP430-Options-1" href="MSP430-Options.html#MSP430-Options">3.17.31 MSP430 Options</a></li>
<li><a name="toc-NDS32-Options-1" href="NDS32-Options.html#NDS32-Options">3.17.32 NDS32 Options</a></li>
<li><a name="toc-Nios-II-Options-1" href="Nios-II-Options.html#Nios-II-Options">3.17.33 Nios II Options</a></li>
<li><a name="toc-PDP_002d11-Options-1" href="PDP_002d11-Options.html#PDP_002d11-Options">3.17.34 PDP-11 Options</a></li>
<li><a name="toc-picoChip-Options-1" href="picoChip-Options.html#picoChip-Options">3.17.35 picoChip Options</a></li>
<li><a name="toc-PowerPC-Options-1" href="PowerPC-Options.html#PowerPC-Options">3.17.36 PowerPC Options</a></li>
<li><a name="toc-RL78-Options-1" href="RL78-Options.html#RL78-Options">3.17.37 RL78 Options</a></li>
<li><a name="toc-IBM-RS_002f6000-and-PowerPC-Options" href="RS_002f6000-and-PowerPC-Options.html#RS_002f6000-and-PowerPC-Options">3.17.38 IBM RS/6000 and PowerPC Options</a></li>
<li><a name="toc-RX-Options-1" href="RX-Options.html#RX-Options">3.17.39 RX Options</a></li>
<li><a name="toc-S_002f390-and-zSeries-Options-1" href="S_002f390-and-zSeries-Options.html#S_002f390-and-zSeries-Options">3.17.40 S/390 and zSeries Options</a></li>
<li><a name="toc-Score-Options-1" href="Score-Options.html#Score-Options">3.17.41 Score Options</a></li>
<li><a name="toc-SH-Options-1" href="SH-Options.html#SH-Options">3.17.42 SH Options</a></li>
<li><a name="toc-Solaris-2-Options-1" href="Solaris-2-Options.html#Solaris-2-Options">3.17.43 Solaris 2 Options</a></li>
<li><a name="toc-SPARC-Options-1" href="SPARC-Options.html#SPARC-Options">3.17.44 SPARC Options</a></li>
<li><a name="toc-SPU-Options-1" href="SPU-Options.html#SPU-Options">3.17.45 SPU Options</a></li>
<li><a name="toc-Options-for-System-V" href="System-V-Options.html#System-V-Options">3.17.46 Options for System V</a></li>
<li><a name="toc-TILE_002dGx-Options-1" href="TILE_002dGx-Options.html#TILE_002dGx-Options">3.17.47 TILE-Gx Options</a></li>
<li><a name="toc-TILEPro-Options-1" href="TILEPro-Options.html#TILEPro-Options">3.17.48 TILEPro Options</a></li>
<li><a name="toc-V850-Options-1" href="V850-Options.html#V850-Options">3.17.49 V850 Options</a></li>
<li><a name="toc-VAX-Options-1" href="VAX-Options.html#VAX-Options">3.17.50 VAX Options</a></li>
<li><a name="toc-VMS-Options-1" href="VMS-Options.html#VMS-Options">3.17.51 VMS Options</a></li>
<li><a name="toc-VxWorks-Options-1" href="VxWorks-Options.html#VxWorks-Options">3.17.52 VxWorks Options</a></li>
<li><a name="toc-x86_002d64-Options-1" href="x86_002d64-Options.html#x86_002d64-Options">3.17.53 x86-64 Options</a></li>
<li><a name="toc-Xstormy16-Options-1" href="Xstormy16-Options.html#Xstormy16-Options">3.17.54 Xstormy16 Options</a></li>
<li><a name="toc-Xtensa-Options-1" href="Xtensa-Options.html#Xtensa-Options">3.17.55 Xtensa Options</a></li>
<li><a name="toc-zSeries-Options-1" href="zSeries-Options.html#zSeries-Options">3.17.56 zSeries Options</a></li>
</ul></li>
<li><a name="toc-Options-for-Code-Generation-Conventions" href="Code-Gen-Options.html#Code-Gen-Options">3.18 Options for Code Generation Conventions</a></li>
<li><a name="toc-Environment-Variables-Affecting-GCC" href="Environment-Variables.html#Environment-Variables">3.19 Environment Variables Affecting GCC</a></li>
<li><a name="toc-Using-Precompiled-Headers" href="Precompiled-Headers.html#Precompiled-Headers">3.20 Using Precompiled Headers</a></li>
</ul></li>
<li><a name="toc-C-Implementation_002ddefined-behavior" href="C-Implementation.html#C-Implementation">4 C Implementation-defined behavior</a>
<ul class="no-bullet">
<li><a name="toc-Translation" href="Translation-implementation.html#Translation-implementation">4.1 Translation</a></li>
<li><a name="toc-Environment" href="Environment-implementation.html#Environment-implementation">4.2 Environment</a></li>
<li><a name="toc-Identifiers" href="Identifiers-implementation.html#Identifiers-implementation">4.3 Identifiers</a></li>
<li><a name="toc-Characters" href="Characters-implementation.html#Characters-implementation">4.4 Characters</a></li>
<li><a name="toc-Integers" href="Integers-implementation.html#Integers-implementation">4.5 Integers</a></li>
<li><a name="toc-Floating-point" href="Floating-point-implementation.html#Floating-point-implementation">4.6 Floating point</a></li>
<li><a name="toc-Arrays-and-pointers" href="Arrays-and-pointers-implementation.html#Arrays-and-pointers-implementation">4.7 Arrays and pointers</a></li>
<li><a name="toc-Hints" href="Hints-implementation.html#Hints-implementation">4.8 Hints</a></li>
<li><a name="toc-Structures_002c-unions_002c-enumerations_002c-and-bit_002dfields" href="Structures-unions-enumerations-and-bit_002dfields-implementation.html#Structures-unions-enumerations-and-bit_002dfields-implementation">4.9 Structures, unions, enumerations, and bit-fields</a></li>
<li><a name="toc-Qualifiers" href="Qualifiers-implementation.html#Qualifiers-implementation">4.10 Qualifiers</a></li>
<li><a name="toc-Declarators" href="Declarators-implementation.html#Declarators-implementation">4.11 Declarators</a></li>
<li><a name="toc-Statements" href="Statements-implementation.html#Statements-implementation">4.12 Statements</a></li>
<li><a name="toc-Preprocessing-directives" href="Preprocessing-directives-implementation.html#Preprocessing-directives-implementation">4.13 Preprocessing directives</a></li>
<li><a name="toc-Library-functions" href="Library-functions-implementation.html#Library-functions-implementation">4.14 Library functions</a></li>
<li><a name="toc-Architecture" href="Architecture-implementation.html#Architecture-implementation">4.15 Architecture</a></li>
<li><a name="toc-Locale_002dspecific-behavior" href="Locale_002dspecific-behavior-implementation.html#Locale_002dspecific-behavior-implementation">4.16 Locale-specific behavior</a></li>
</ul></li>
<li><a name="toc-C_002b_002b-Implementation_002ddefined-behavior" href="C_002b_002b-Implementation.html#C_002b_002b-Implementation">5 C++ Implementation-defined behavior</a>
<ul class="no-bullet">
<li><a name="toc-Conditionally_002dsupported-behavior-1" href="Conditionally_002dsupported-behavior.html#Conditionally_002dsupported-behavior">5.1 Conditionally-supported behavior</a></li>
<li><a name="toc-Exception-handling-1" href="Exception-handling.html#Exception-handling">5.2 Exception handling</a></li>
</ul></li>
<li><a name="toc-Extensions-to-the-C-Language-Family" href="C-Extensions.html#C-Extensions">6 Extensions to the C Language Family</a>
<ul class="no-bullet">
<li><a name="toc-Statements-and-Declarations-in-Expressions" href="Statement-Exprs.html#Statement-Exprs">6.1 Statements and Declarations in Expressions</a></li>
<li><a name="toc-Locally-Declared-Labels" href="Local-Labels.html#Local-Labels">6.2 Locally Declared Labels</a></li>
<li><a name="toc-Labels-as-Values-1" href="Labels-as-Values.html#Labels-as-Values">6.3 Labels as Values</a></li>
<li><a name="toc-Nested-Functions-1" href="Nested-Functions.html#Nested-Functions">6.4 Nested Functions</a></li>
<li><a name="toc-Constructing-Function-Calls" href="Constructing-Calls.html#Constructing-Calls">6.5 Constructing Function Calls</a></li>
<li><a name="toc-Referring-to-a-Type-with-typeof" href="Typeof.html#Typeof">6.6 Referring to a Type with <code>typeof</code></a></li>
<li><a name="toc-Conditionals-with-Omitted-Operands" href="Conditionals.html#Conditionals">6.7 Conditionals with Omitted Operands</a></li>
<li><a name="toc-128_002dbit-integers" href="_005f_005fint128.html#g_t_005f_005fint128">6.8 128-bit integers</a></li>
<li><a name="toc-Double_002dWord-Integers" href="Long-Long.html#Long-Long">6.9 Double-Word Integers</a></li>
<li><a name="toc-Complex-Numbers" href="Complex.html#Complex">6.10 Complex Numbers</a></li>
<li><a name="toc-Additional-Floating-Types" href="Floating-Types.html#Floating-Types">6.11 Additional Floating Types</a></li>
<li><a name="toc-Half_002dPrecision-Floating-Point" href="Half_002dPrecision.html#Half_002dPrecision">6.12 Half-Precision Floating Point</a></li>
<li><a name="toc-Decimal-Floating-Types" href="Decimal-Float.html#Decimal-Float">6.13 Decimal Floating Types</a></li>
<li><a name="toc-Hex-Floats-1" href="Hex-Floats.html#Hex-Floats">6.14 Hex Floats</a></li>
<li><a name="toc-Fixed_002dPoint-Types" href="Fixed_002dPoint.html#Fixed_002dPoint">6.15 Fixed-Point Types</a></li>
<li><a name="toc-Named-Address-Spaces-1" href="Named-Address-Spaces.html#Named-Address-Spaces">6.16 Named Address Spaces</a>
<ul class="no-bullet">
<li><a name="toc-AVR-Named-Address-Spaces-1" href="Named-Address-Spaces.html#AVR-Named-Address-Spaces-1">6.16.1 AVR Named Address Spaces</a></li>
<li><a name="toc-M32C-Named-Address-Spaces" href="Named-Address-Spaces.html#M32C-Named-Address-Spaces">6.16.2 M32C Named Address Spaces</a></li>
<li><a name="toc-RL78-Named-Address-Spaces" href="Named-Address-Spaces.html#RL78-Named-Address-Spaces">6.16.3 RL78 Named Address Spaces</a></li>
<li><a name="toc-SPU-Named-Address-Spaces" href="Named-Address-Spaces.html#SPU-Named-Address-Spaces">6.16.4 SPU Named Address Spaces</a></li>
</ul></li>
<li><a name="toc-Arrays-of-Length-Zero" href="Zero-Length.html#Zero-Length">6.17 Arrays of Length Zero</a></li>
<li><a name="toc-Structures-With-No-Members" href="Empty-Structures.html#Empty-Structures">6.18 Structures With No Members</a></li>
<li><a name="toc-Arrays-of-Variable-Length" href="Variable-Length.html#Variable-Length">6.19 Arrays of Variable Length</a></li>
<li><a name="toc-Macros-with-a-Variable-Number-of-Arguments_002e" href="Variadic-Macros.html#Variadic-Macros">6.20 Macros with a Variable Number of Arguments.</a></li>
<li><a name="toc-Slightly-Looser-Rules-for-Escaped-Newlines" href="Escaped-Newlines.html#Escaped-Newlines">6.21 Slightly Looser Rules for Escaped Newlines</a></li>
<li><a name="toc-Non_002dLvalue-Arrays-May-Have-Subscripts" href="Subscripting.html#Subscripting">6.22 Non-Lvalue Arrays May Have Subscripts</a></li>
<li><a name="toc-Arithmetic-on-void_002d-and-Function_002dPointers" href="Pointer-Arith.html#Pointer-Arith">6.23 Arithmetic on <code>void</code>- and Function-Pointers</a></li>
<li><a name="toc-Non_002dConstant-Initializers" href="Initializers.html#Initializers">6.24 Non-Constant Initializers</a></li>
<li><a name="toc-Compound-Literals-1" href="Compound-Literals.html#Compound-Literals">6.25 Compound Literals</a></li>
<li><a name="toc-Designated-Initializers" href="Designated-Inits.html#Designated-Inits">6.26 Designated Initializers</a></li>
<li><a name="toc-Case-Ranges-1" href="Case-Ranges.html#Case-Ranges">6.27 Case Ranges</a></li>
<li><a name="toc-Cast-to-a-Union-Type" href="Cast-to-Union.html#Cast-to-Union">6.28 Cast to a Union Type</a></li>
<li><a name="toc-Mixed-Declarations-and-Code" href="Mixed-Declarations.html#Mixed-Declarations">6.29 Mixed Declarations and Code</a></li>
<li><a name="toc-Declaring-Attributes-of-Functions" href="Function-Attributes.html#Function-Attributes">6.30 Declaring Attributes of Functions</a></li>
<li><a name="toc-Attribute-Syntax-1" href="Attribute-Syntax.html#Attribute-Syntax">6.31 Attribute Syntax</a></li>
<li><a name="toc-Prototypes-and-Old_002dStyle-Function-Definitions" href="Function-Prototypes.html#Function-Prototypes">6.32 Prototypes and Old-Style Function Definitions</a></li>
<li><a name="toc-C_002b_002b-Style-Comments" href="C_002b_002b-Comments.html#C_002b_002b-Comments">6.33 C++ Style Comments</a></li>
<li><a name="toc-Dollar-Signs-in-Identifier-Names" href="Dollar-Signs.html#Dollar-Signs">6.34 Dollar Signs in Identifier Names</a></li>
<li><a name="toc-The-Character-ESC-in-Constants" href="Character-Escapes.html#Character-Escapes">6.35 The Character <tt class="key">ESC</tt> in Constants</a></li>
<li><a name="toc-Specifying-Attributes-of-Variables" href="Variable-Attributes.html#Variable-Attributes">6.36 Specifying Attributes of Variables</a>
<ul class="no-bullet">
<li><a name="toc-AVR-Variable-Attributes-1" href="Variable-Attributes.html#AVR-Variable-Attributes-1">6.36.1 AVR Variable Attributes</a></li>
<li><a name="toc-Blackfin-Variable-Attributes" href="Variable-Attributes.html#Blackfin-Variable-Attributes">6.36.2 Blackfin Variable Attributes</a></li>
<li><a name="toc-M32R_002fD-Variable-Attributes" href="Variable-Attributes.html#M32R_002fD-Variable-Attributes">6.36.3 M32R/D Variable Attributes</a></li>
<li><a name="toc-MeP-Variable-Attributes-1" href="Variable-Attributes.html#MeP-Variable-Attributes-1">6.36.4 MeP Variable Attributes</a></li>
<li><a name="toc-i386-Variable-Attributes-1" href="Variable-Attributes.html#i386-Variable-Attributes-1">6.36.5 i386 Variable Attributes</a></li>
<li><a name="toc-PowerPC-Variable-Attributes" href="Variable-Attributes.html#PowerPC-Variable-Attributes">6.36.6 PowerPC Variable Attributes</a></li>
<li><a name="toc-SPU-Variable-Attributes" href="Variable-Attributes.html#SPU-Variable-Attributes">6.36.7 SPU Variable Attributes</a></li>
<li><a name="toc-Xstormy16-Variable-Attributes" href="Variable-Attributes.html#Xstormy16-Variable-Attributes">6.36.8 Xstormy16 Variable Attributes</a></li>
</ul></li>
<li><a name="toc-Specifying-Attributes-of-Types" href="Type-Attributes.html#Type-Attributes">6.37 Specifying Attributes of Types</a>
<ul class="no-bullet">
<li><a name="toc-ARM-Type-Attributes" href="Type-Attributes.html#ARM-Type-Attributes">6.37.1 ARM Type Attributes</a></li>
<li><a name="toc-MeP-Type-Attributes-1" href="Type-Attributes.html#MeP-Type-Attributes-1">6.37.2 MeP Type Attributes</a></li>
<li><a name="toc-i386-Type-Attributes-1" href="Type-Attributes.html#i386-Type-Attributes-1">6.37.3 i386 Type Attributes</a></li>
<li><a name="toc-PowerPC-Type-Attributes-1" href="Type-Attributes.html#PowerPC-Type-Attributes-1">6.37.4 PowerPC Type Attributes</a></li>
<li><a name="toc-SPU-Type-Attributes-1" href="Type-Attributes.html#SPU-Type-Attributes-1">6.37.5 SPU Type Attributes</a></li>
</ul></li>
<li><a name="toc-Inquiring-on-Alignment-of-Types-or-Variables" href="Alignment.html#Alignment">6.38 Inquiring on Alignment of Types or Variables</a></li>
<li><a name="toc-An-Inline-Function-is-As-Fast-As-a-Macro" href="Inline.html#Inline">6.39 An Inline Function is As Fast As a Macro</a></li>
<li><a name="toc-When-is-a-Volatile-Object-Accessed_003f" href="Volatiles.html#Volatiles">6.40 When is a Volatile Object Accessed?</a></li>
<li><a name="toc-Assembler-Instructions-with-C-Expression-Operands" href="Extended-Asm.html#Extended-Asm">6.41 Assembler Instructions with C Expression Operands</a>
<ul class="no-bullet">
<li><a name="toc-Size-of-an-asm" href="Extended-Asm.html#Size-of-an-asm">6.41.1 Size of an <code>asm</code></a></li>
<li><a name="toc-i386-floating_002dpoint-asm-operands" href="Extended-Asm.html#i386-floating_002dpoint-asm-operands">6.41.2 i386 floating-point asm operands</a></li>
</ul></li>
<li><a name="toc-Constraints-for-asm-Operands" href="Constraints.html#Constraints">6.42 Constraints for <code>asm</code> Operands</a>
<ul class="no-bullet">
<li><a name="toc-Simple-Constraints-1" href="Simple-Constraints.html#Simple-Constraints">6.42.1 Simple Constraints</a></li>
<li><a name="toc-Multiple-Alternative-Constraints" href="Multi_002dAlternative.html#Multi_002dAlternative">6.42.2 Multiple Alternative Constraints</a></li>
<li><a name="toc-Constraint-Modifier-Characters" href="Modifiers.html#Modifiers">6.42.3 Constraint Modifier Characters</a></li>
<li><a name="toc-Constraints-for-Particular-Machines" href="Machine-Constraints.html#Machine-Constraints">6.42.4 Constraints for Particular Machines</a></li>
</ul></li>
<li><a name="toc-Controlling-Names-Used-in-Assembler-Code" href="Asm-Labels.html#Asm-Labels">6.43 Controlling Names Used in Assembler Code</a></li>
<li><a name="toc-Variables-in-Specified-Registers" href="Explicit-Reg-Vars.html#Explicit-Reg-Vars">6.44 Variables in Specified Registers</a>
<ul class="no-bullet">
<li><a name="toc-Defining-Global-Register-Variables" href="Global-Reg-Vars.html#Global-Reg-Vars">6.44.1 Defining Global Register Variables</a></li>
<li><a name="toc-Specifying-Registers-for-Local-Variables" href="Local-Reg-Vars.html#Local-Reg-Vars">6.44.2 Specifying Registers for Local Variables</a></li>
</ul></li>
<li><a name="toc-Alternate-Keywords-1" href="Alternate-Keywords.html#Alternate-Keywords">6.45 Alternate Keywords</a></li>
<li><a name="toc-Incomplete-enum-Types" href="Incomplete-Enums.html#Incomplete-Enums">6.46 Incomplete <code>enum</code> Types</a></li>
<li><a name="toc-Function-Names-as-Strings" href="Function-Names.html#Function-Names">6.47 Function Names as Strings</a></li>
<li><a name="toc-Getting-the-Return-or-Frame-Address-of-a-Function" href="Return-Address.html#Return-Address">6.48 Getting the Return or Frame Address of a Function</a></li>
<li><a name="toc-Using-Vector-Instructions-through-Built_002din-Functions" href="Vector-Extensions.html#Vector-Extensions">6.49 Using Vector Instructions through Built-in Functions</a></li>
<li><a name="toc-Offsetof-1" href="Offsetof.html#Offsetof">6.50 Offsetof</a></li>
<li><a name="toc-Legacy-_005f_005fsync-Built_002din-Functions-for-Atomic-Memory-Access" href="_005f_005fsync-Builtins.html#g_t_005f_005fsync-Builtins">6.51 Legacy __sync Built-in Functions for Atomic Memory Access</a></li>
<li><a name="toc-Built_002din-functions-for-memory-model-aware-atomic-operations" href="_005f_005fatomic-Builtins.html#g_t_005f_005fatomic-Builtins">6.52 Built-in functions for memory model aware atomic operations</a></li>
<li><a name="toc-x86-specific-memory-model-extensions-for-transactional-memory-1" href="x86-specific-memory-model-extensions-for-transactional-memory.html#x86-specific-memory-model-extensions-for-transactional-memory">6.53 x86 specific memory model extensions for transactional memory</a></li>
<li><a name="toc-Object-Size-Checking-Built_002din-Functions" href="Object-Size-Checking.html#Object-Size-Checking">6.54 Object Size Checking Built-in Functions</a></li>
<li><a name="toc-Cilk-Plus-C_002fC_002b_002b-language-extension-Built_002din-Functions_002e" href="Cilk-Plus-Builtins.html#Cilk-Plus-Builtins">6.55 Cilk Plus C/C++ language extension Built-in Functions.</a></li>
<li><a name="toc-Other-Built_002din-Functions-Provided-by-GCC" href="Other-Builtins.html#Other-Builtins">6.56 Other Built-in Functions Provided by GCC</a></li>
<li><a name="toc-Built_002din-Functions-Specific-to-Particular-Target-Machines" href="Target-Builtins.html#Target-Builtins">6.57 Built-in Functions Specific to Particular Target Machines</a>
<ul class="no-bullet">
<li><a name="toc-AArch64-Built_002din-Functions-1" href="AArch64-Built_002din-Functions.html#AArch64-Built_002din-Functions">6.57.1 AArch64 Built-in Functions</a></li>
<li><a name="toc-Alpha-Built_002din-Functions-1" href="Alpha-Built_002din-Functions.html#Alpha-Built_002din-Functions">6.57.2 Alpha Built-in Functions</a></li>
<li><a name="toc-Altera-Nios-II-Built_002din-Functions-1" href="Altera-Nios-II-Built_002din-Functions.html#Altera-Nios-II-Built_002din-Functions">6.57.3 Altera Nios II Built-in Functions</a></li>
<li><a name="toc-ARC-Built_002din-Functions-1" href="ARC-Built_002din-Functions.html#ARC-Built_002din-Functions">6.57.4 ARC Built-in Functions</a></li>
<li><a name="toc-ARC-SIMD-Built_002din-Functions-1" href="ARC-SIMD-Built_002din-Functions.html#ARC-SIMD-Built_002din-Functions">6.57.5 ARC SIMD Built-in Functions</a></li>
<li><a name="toc-ARM-iWMMXt-Built_002din-Functions-1" href="ARM-iWMMXt-Built_002din-Functions.html#ARM-iWMMXt-Built_002din-Functions">6.57.6 ARM iWMMXt Built-in Functions</a></li>
<li><a name="toc-ARM-C-Language-Extensions-_0028ACLE_0029-1" href="ARM-C-Language-Extensions-_0028ACLE_0029.html#ARM-C-Language-Extensions-_0028ACLE_0029">6.57.7 ARM C Language Extensions (ACLE)</a></li>
<li><a name="toc-ARM-Floating-Point-Status-and-Control-Intrinsics-1" href="ARM-Floating-Point-Status-and-Control-Intrinsics.html#ARM-Floating-Point-Status-and-Control-Intrinsics">6.57.8 ARM Floating Point Status and Control Intrinsics</a></li>
<li><a name="toc-AVR-Built_002din-Functions-1" href="AVR-Built_002din-Functions.html#AVR-Built_002din-Functions">6.57.9 AVR Built-in Functions</a></li>
<li><a name="toc-Blackfin-Built_002din-Functions-1" href="Blackfin-Built_002din-Functions.html#Blackfin-Built_002din-Functions">6.57.10 Blackfin Built-in Functions</a></li>
<li><a name="toc-FR_002dV-Built_002din-Functions-1" href="FR_002dV-Built_002din-Functions.html#FR_002dV-Built_002din-Functions">6.57.11 FR-V Built-in Functions</a>
<ul class="no-bullet">
<li><a name="toc-Argument-Types-1" href="Argument-Types.html#Argument-Types">6.57.11.1 Argument Types</a></li>
<li><a name="toc-Directly_002dmapped-Integer-Functions-1" href="Directly_002dmapped-Integer-Functions.html#Directly_002dmapped-Integer-Functions">6.57.11.2 Directly-mapped Integer Functions</a></li>
<li><a name="toc-Directly_002dmapped-Media-Functions-1" href="Directly_002dmapped-Media-Functions.html#Directly_002dmapped-Media-Functions">6.57.11.3 Directly-mapped Media Functions</a></li>
<li><a name="toc-Raw-read_002fwrite-Functions-1" href="Raw-read_002fwrite-Functions.html#Raw-read_002fwrite-Functions">6.57.11.4 Raw read/write Functions</a></li>
<li><a name="toc-Other-Built_002din-Functions-1" href="Other-Built_002din-Functions.html#Other-Built_002din-Functions">6.57.11.5 Other Built-in Functions</a></li>
</ul></li>
<li><a name="toc-X86-Built_002din-Functions-1" href="X86-Built_002din-Functions.html#X86-Built_002din-Functions">6.57.12 X86 Built-in Functions</a></li>
<li><a name="toc-X86-transaction-memory-intrinsics" href="X86-transactional-memory-intrinsics.html#X86-transactional-memory-intrinsics">6.57.13 X86 transaction memory intrinsics</a></li>
<li><a name="toc-MIPS-DSP-Built_002din-Functions-1" href="MIPS-DSP-Built_002din-Functions.html#MIPS-DSP-Built_002din-Functions">6.57.14 MIPS DSP Built-in Functions</a></li>
<li><a name="toc-MIPS-Paired_002dSingle-Support-1" href="MIPS-Paired_002dSingle-Support.html#MIPS-Paired_002dSingle-Support">6.57.15 MIPS Paired-Single Support</a></li>
<li><a name="toc-MIPS-Loongson-Built_002din-Functions-1" href="MIPS-Loongson-Built_002din-Functions.html#MIPS-Loongson-Built_002din-Functions">6.57.16 MIPS Loongson Built-in Functions</a>
<ul class="no-bullet">
<li><a name="toc-Paired_002dSingle-Arithmetic-1" href="Paired_002dSingle-Arithmetic.html#Paired_002dSingle-Arithmetic">6.57.16.1 Paired-Single Arithmetic</a></li>
<li><a name="toc-Paired_002dSingle-Built_002din-Functions-1" href="Paired_002dSingle-Built_002din-Functions.html#Paired_002dSingle-Built_002din-Functions">6.57.16.2 Paired-Single Built-in Functions</a></li>
<li><a name="toc-MIPS_002d3D-Built_002din-Functions-1" href="MIPS_002d3D-Built_002din-Functions.html#MIPS_002d3D-Built_002din-Functions">6.57.16.3 MIPS-3D Built-in Functions</a></li>
</ul></li>
<li><a name="toc-Other-MIPS-Built_002din-Functions-1" href="Other-MIPS-Built_002din-Functions.html#Other-MIPS-Built_002din-Functions">6.57.17 Other MIPS Built-in Functions</a></li>
<li><a name="toc-MSP430-Built_002din-Functions-1" href="MSP430-Built_002din-Functions.html#MSP430-Built_002din-Functions">6.57.18 MSP430 Built-in Functions</a></li>
<li><a name="toc-NDS32-Built_002din-Functions-1" href="NDS32-Built_002din-Functions.html#NDS32-Built_002din-Functions">6.57.19 NDS32 Built-in Functions</a></li>
<li><a name="toc-picoChip-Built_002din-Functions-1" href="picoChip-Built_002din-Functions.html#picoChip-Built_002din-Functions">6.57.20 picoChip Built-in Functions</a></li>
<li><a name="toc-PowerPC-Built_002din-Functions-1" href="PowerPC-Built_002din-Functions.html#PowerPC-Built_002din-Functions">6.57.21 PowerPC Built-in Functions</a></li>
<li><a name="toc-PowerPC-AltiVec-Built_002din-Functions" href="PowerPC-AltiVec_002fVSX-Built_002din-Functions.html#PowerPC-AltiVec_002fVSX-Built_002din-Functions">6.57.22 PowerPC AltiVec Built-in Functions</a></li>
<li><a name="toc-PowerPC-Hardware-Transactional-Memory-Built_002din-Functions-1" href="PowerPC-Hardware-Transactional-Memory-Built_002din-Functions.html#PowerPC-Hardware-Transactional-Memory-Built_002din-Functions">6.57.23 PowerPC Hardware Transactional Memory Built-in Functions</a>
<ul class="no-bullet">
<li><a name="toc-PowerPC-HTM-Low-Level-Built_002din-Functions" href="PowerPC-Hardware-Transactional-Memory-Built_002din-Functions.html#PowerPC-HTM-Low-Level-Built_002din-Functions">6.57.23.1 PowerPC HTM Low Level Built-in Functions</a></li>
<li><a name="toc-PowerPC-HTM-High-Level-Inline-Functions" href="PowerPC-Hardware-Transactional-Memory-Built_002din-Functions.html#PowerPC-HTM-High-Level-Inline-Functions">6.57.23.2 PowerPC HTM High Level Inline Functions</a></li>
</ul></li>
<li><a name="toc-RX-Built_002din-Functions-1" href="RX-Built_002din-Functions.html#RX-Built_002din-Functions">6.57.24 RX Built-in Functions</a></li>
<li><a name="toc-S_002f390-System-z-Built_002din-Functions-1" href="S_002f390-System-z-Built_002din-Functions.html#S_002f390-System-z-Built_002din-Functions">6.57.25 S/390 System z Built-in Functions</a></li>
<li><a name="toc-SH-Built_002din-Functions-1" href="SH-Built_002din-Functions.html#SH-Built_002din-Functions">6.57.26 SH Built-in Functions</a></li>
<li><a name="toc-SPARC-VIS-Built_002din-Functions-1" href="SPARC-VIS-Built_002din-Functions.html#SPARC-VIS-Built_002din-Functions">6.57.27 SPARC VIS Built-in Functions</a></li>
<li><a name="toc-SPU-Built_002din-Functions-1" href="SPU-Built_002din-Functions.html#SPU-Built_002din-Functions">6.57.28 SPU Built-in Functions</a></li>
<li><a name="toc-TI-C6X-Built_002din-Functions-1" href="TI-C6X-Built_002din-Functions.html#TI-C6X-Built_002din-Functions">6.57.29 TI C6X Built-in Functions</a></li>
<li><a name="toc-TILE_002dGx-Built_002din-Functions-1" href="TILE_002dGx-Built_002din-Functions.html#TILE_002dGx-Built_002din-Functions">6.57.30 TILE-Gx Built-in Functions</a></li>
<li><a name="toc-TILEPro-Built_002din-Functions-1" href="TILEPro-Built_002din-Functions.html#TILEPro-Built_002din-Functions">6.57.31 TILEPro Built-in Functions</a></li>
</ul></li>
<li><a name="toc-Format-Checks-Specific-to-Particular-Target-Machines" href="Target-Format-Checks.html#Target-Format-Checks">6.58 Format Checks Specific to Particular Target Machines</a>
<ul class="no-bullet">
<li><a name="toc-Solaris-Format-Checks-1" href="Solaris-Format-Checks.html#Solaris-Format-Checks">6.58.1 Solaris Format Checks</a></li>
<li><a name="toc-Darwin-Format-Checks-1" href="Darwin-Format-Checks.html#Darwin-Format-Checks">6.58.2 Darwin Format Checks</a></li>
</ul></li>
<li><a name="toc-Pragmas-Accepted-by-GCC" href="Pragmas.html#Pragmas">6.59 Pragmas Accepted by GCC</a>
<ul class="no-bullet">
<li><a name="toc-ARM-Pragmas-1" href="ARM-Pragmas.html#ARM-Pragmas">6.59.1 ARM Pragmas</a></li>
<li><a name="toc-M32C-Pragmas-1" href="M32C-Pragmas.html#M32C-Pragmas">6.59.2 M32C Pragmas</a></li>
<li><a name="toc-MeP-Pragmas-1" href="MeP-Pragmas.html#MeP-Pragmas">6.59.3 MeP Pragmas</a></li>
<li><a name="toc-RS_002f6000-and-PowerPC-Pragmas-1" href="RS_002f6000-and-PowerPC-Pragmas.html#RS_002f6000-and-PowerPC-Pragmas">6.59.4 RS/6000 and PowerPC Pragmas</a></li>
<li><a name="toc-Darwin-Pragmas-1" href="Darwin-Pragmas.html#Darwin-Pragmas">6.59.5 Darwin Pragmas</a></li>
<li><a name="toc-Solaris-Pragmas-1" href="Solaris-Pragmas.html#Solaris-Pragmas">6.59.6 Solaris Pragmas</a></li>
<li><a name="toc-Symbol_002dRenaming-Pragmas-1" href="Symbol_002dRenaming-Pragmas.html#Symbol_002dRenaming-Pragmas">6.59.7 Symbol-Renaming Pragmas</a></li>
<li><a name="toc-Structure_002dPacking-Pragmas-1" href="Structure_002dPacking-Pragmas.html#Structure_002dPacking-Pragmas">6.59.8 Structure-Packing Pragmas</a></li>
<li><a name="toc-Weak-Pragmas-1" href="Weak-Pragmas.html#Weak-Pragmas">6.59.9 Weak Pragmas</a></li>
<li><a name="toc-Diagnostic-Pragmas-1" href="Diagnostic-Pragmas.html#Diagnostic-Pragmas">6.59.10 Diagnostic Pragmas</a></li>
<li><a name="toc-Visibility-Pragmas-1" href="Visibility-Pragmas.html#Visibility-Pragmas">6.59.11 Visibility Pragmas</a></li>
<li><a name="toc-Push_002fPop-Macro-Pragmas-1" href="Push_002fPop-Macro-Pragmas.html#Push_002fPop-Macro-Pragmas">6.59.12 Push/Pop Macro Pragmas</a></li>
<li><a name="toc-Function-Specific-Option-Pragmas-1" href="Function-Specific-Option-Pragmas.html#Function-Specific-Option-Pragmas">6.59.13 Function Specific Option Pragmas</a></li>
<li><a name="toc-Loop_002dSpecific-Pragmas-1" href="Loop_002dSpecific-Pragmas.html#Loop_002dSpecific-Pragmas">6.59.14 Loop-Specific Pragmas</a></li>
</ul></li>
<li><a name="toc-Unnamed-struct_002funion-fields-within-structs_002funions" href="Unnamed-Fields.html#Unnamed-Fields">6.60 Unnamed struct/union fields within structs/unions</a></li>
<li><a name="toc-Thread_002dLocal-Storage" href="Thread_002dLocal.html#Thread_002dLocal">6.61 Thread-Local Storage</a>
<ul class="no-bullet">
<li><a name="toc-ISO_002fIEC-9899_003a1999-Edits-for-Thread_002dLocal-Storage" href="C99-Thread_002dLocal-Edits.html#C99-Thread_002dLocal-Edits">6.61.1 ISO/IEC 9899:1999 Edits for Thread-Local Storage</a></li>
<li><a name="toc-ISO_002fIEC-14882_003a1998-Edits-for-Thread_002dLocal-Storage" href="C_002b_002b98-Thread_002dLocal-Edits.html#C_002b_002b98-Thread_002dLocal-Edits">6.61.2 ISO/IEC 14882:1998 Edits for Thread-Local Storage</a></li>
</ul></li>
<li><a name="toc-Binary-constants-using-the-0b-prefix" href="Binary-constants.html#Binary-constants">6.62 Binary constants using the &lsquo;<samp>0b</samp>&rsquo; prefix</a></li>
</ul></li>
<li><a name="toc-Extensions-to-the-C_002b_002b-Language" href="C_002b_002b-Extensions.html#C_002b_002b-Extensions">7 Extensions to the C++ Language</a>
<ul class="no-bullet">
<li><a name="toc-When-is-a-Volatile-C_002b_002b-Object-Accessed_003f" href="C_002b_002b-Volatiles.html#C_002b_002b-Volatiles">7.1 When is a Volatile C++ Object Accessed?</a></li>
<li><a name="toc-Restricting-Pointer-Aliasing" href="Restricted-Pointers.html#Restricted-Pointers">7.2 Restricting Pointer Aliasing</a></li>
<li><a name="toc-Vague-Linkage-1" href="Vague-Linkage.html#Vague-Linkage">7.3 Vague Linkage</a></li>
<li><a name="toc-_0023pragma-interface-and-implementation" href="C_002b_002b-Interface.html#C_002b_002b-Interface">7.4 #pragma interface and implementation</a></li>
<li><a name="toc-Where_0027s-the-Template_003f" href="Template-Instantiation.html#Template-Instantiation">7.5 Where&rsquo;s the Template?</a></li>
<li><a name="toc-Extracting-the-function-pointer-from-a-bound-pointer-to-member-function" href="Bound-member-functions.html#Bound-member-functions">7.6 Extracting the function pointer from a bound pointer to member function</a></li>
<li><a name="toc-C_002b_002b_002dSpecific-Variable_002c-Function_002c-and-Type-Attributes" href="C_002b_002b-Attributes.html#C_002b_002b-Attributes">7.7 C++-Specific Variable, Function, and Type Attributes</a></li>
<li><a name="toc-Function-Multiversioning-1" href="Function-Multiversioning.html#Function-Multiversioning">7.8 Function Multiversioning</a></li>
<li><a name="toc-Namespace-Association-1" href="Namespace-Association.html#Namespace-Association">7.9 Namespace Association</a></li>
<li><a name="toc-Type-Traits-1" href="Type-Traits.html#Type-Traits">7.10 Type Traits</a></li>
<li><a name="toc-Java-Exceptions-1" href="Java-Exceptions.html#Java-Exceptions">7.11 Java Exceptions</a></li>
<li><a name="toc-Deprecated-Features-1" href="Deprecated-Features.html#Deprecated-Features">7.12 Deprecated Features</a></li>
<li><a name="toc-Backwards-Compatibility-1" href="Backwards-Compatibility.html#Backwards-Compatibility">7.13 Backwards Compatibility</a></li>
</ul></li>
<li><a name="toc-GNU-Objective_002dC-features" href="Objective_002dC.html#Objective_002dC">8 GNU Objective-C features</a>
<ul class="no-bullet">
<li><a name="toc-GNU-Objective_002dC-runtime-API-1" href="GNU-Objective_002dC-runtime-API.html#GNU-Objective_002dC-runtime-API">8.1 GNU Objective-C runtime API</a>
<ul class="no-bullet">
<li><a name="toc-Modern-GNU-Objective_002dC-runtime-API-1" href="Modern-GNU-Objective_002dC-runtime-API.html#Modern-GNU-Objective_002dC-runtime-API">8.1.1 Modern GNU Objective-C runtime API</a></li>
<li><a name="toc-Traditional-GNU-Objective_002dC-runtime-API-1" href="Traditional-GNU-Objective_002dC-runtime-API.html#Traditional-GNU-Objective_002dC-runtime-API">8.1.2 Traditional GNU Objective-C runtime API</a></li>
</ul></li>
<li><a name="toc-_002bload_003a-Executing-code-before-main" href="Executing-code-before-main.html#Executing-code-before-main">8.2 <code>+load</code>: Executing code before main</a>
<ul class="no-bullet">
<li><a name="toc-What-you-can-and-what-you-cannot-do-in-_002bload-1" href="What-you-can-and-what-you-cannot-do-in-_002bload.html#What-you-can-and-what-you-cannot-do-in-_002bload">8.2.1 What you can and what you cannot do in <code>+load</code></a></li>
</ul></li>
<li><a name="toc-Type-encoding-1" href="Type-encoding.html#Type-encoding">8.3 Type encoding</a>
<ul class="no-bullet">
<li><a name="toc-Legacy-type-encoding-1" href="Legacy-type-encoding.html#Legacy-type-encoding">8.3.1 Legacy type encoding</a></li>
<li><a name="toc-_0040encode-1" href="_0040encode.html#g_t_0040encode">8.3.2 @encode</a></li>
<li><a name="toc-Method-signatures-1" href="Method-signatures.html#Method-signatures">8.3.3 Method signatures</a></li>
</ul></li>
<li><a name="toc-Garbage-Collection-1" href="Garbage-Collection.html#Garbage-Collection">8.4 Garbage Collection</a></li>
<li><a name="toc-Constant-string-objects-1" href="Constant-string-objects.html#Constant-string-objects">8.5 Constant string objects</a></li>
<li><a name="toc-compatibility_005falias-1" href="compatibility_005falias.html#compatibility_005falias">8.6 compatibility_alias</a></li>
<li><a name="toc-Exceptions-1" href="Exceptions.html#Exceptions">8.7 Exceptions</a></li>
<li><a name="toc-Synchronization-1" href="Synchronization.html#Synchronization">8.8 Synchronization</a></li>
<li><a name="toc-Fast-enumeration-1" href="Fast-enumeration.html#Fast-enumeration">8.9 Fast enumeration</a>
<ul class="no-bullet">
<li><a name="toc-Using-fast-enumeration-1" href="Using-fast-enumeration.html#Using-fast-enumeration">8.9.1 Using fast enumeration</a></li>
<li><a name="toc-c99_002dlike-fast-enumeration-syntax-1" href="c99_002dlike-fast-enumeration-syntax.html#c99_002dlike-fast-enumeration-syntax">8.9.2 c99-like fast enumeration syntax</a></li>
<li><a name="toc-Fast-enumeration-details-1" href="Fast-enumeration-details.html#Fast-enumeration-details">8.9.3 Fast enumeration details</a></li>
<li><a name="toc-Fast-enumeration-protocol-1" href="Fast-enumeration-protocol.html#Fast-enumeration-protocol">8.9.4 Fast enumeration protocol</a></li>
</ul></li>
<li><a name="toc-Messaging-with-the-GNU-Objective_002dC-runtime-1" href="Messaging-with-the-GNU-Objective_002dC-runtime.html#Messaging-with-the-GNU-Objective_002dC-runtime">8.10 Messaging with the GNU Objective-C runtime</a>
<ul class="no-bullet">
<li><a name="toc-Dynamically-registering-methods-1" href="Dynamically-registering-methods.html#Dynamically-registering-methods">8.10.1 Dynamically registering methods</a></li>
<li><a name="toc-Forwarding-hook-1" href="Forwarding-hook.html#Forwarding-hook">8.10.2 Forwarding hook</a></li>
</ul></li>
</ul></li>
<li><a name="toc-Binary-Compatibility" href="Compatibility.html#Compatibility">9 Binary Compatibility</a></li>
<li><a name="toc-gcov_002d_002d_002da-Test-Coverage-Program" href="Gcov.html#Gcov">10 <code>gcov</code>&mdash;a Test Coverage Program</a>
<ul class="no-bullet">
<li><a name="toc-Introduction-to-gcov" href="Gcov-Intro.html#Gcov-Intro">10.1 Introduction to <code>gcov</code></a></li>
<li><a name="toc-Invoking-gcov" href="Invoking-Gcov.html#Invoking-Gcov">10.2 Invoking <code>gcov</code></a></li>
<li><a name="toc-Using-gcov-with-GCC-Optimization" href="Gcov-and-Optimization.html#Gcov-and-Optimization">10.3 Using <code>gcov</code> with GCC Optimization</a></li>
<li><a name="toc-Brief-description-of-gcov-data-files" href="Gcov-Data-Files.html#Gcov-Data-Files">10.4 Brief description of <code>gcov</code> data files</a></li>
<li><a name="toc-Data-file-relocation-to-support-cross_002dprofiling" href="Cross_002dprofiling.html#Cross_002dprofiling">10.5 Data file relocation to support cross-profiling</a></li>
</ul></li>
<li><a name="toc-Known-Causes-of-Trouble-with-GCC" href="Trouble.html#Trouble">11 Known Causes of Trouble with GCC</a>
<ul class="no-bullet">
<li><a name="toc-Actual-Bugs-We-Haven_0027t-Fixed-Yet" href="Actual-Bugs.html#Actual-Bugs">11.1 Actual Bugs We Haven&rsquo;t Fixed Yet</a></li>
<li><a name="toc-Interoperation-1" href="Interoperation.html#Interoperation">11.2 Interoperation</a></li>
<li><a name="toc-Incompatibilities-of-GCC" href="Incompatibilities.html#Incompatibilities">11.3 Incompatibilities of GCC</a></li>
<li><a name="toc-Fixed-Header-Files" href="Fixed-Headers.html#Fixed-Headers">11.4 Fixed Header Files</a></li>
<li><a name="toc-Standard-Libraries-1" href="Standard-Libraries.html#Standard-Libraries">11.5 Standard Libraries</a></li>
<li><a name="toc-Disappointments-and-Misunderstandings" href="Disappointments.html#Disappointments">11.6 Disappointments and Misunderstandings</a></li>
<li><a name="toc-Common-Misunderstandings-with-GNU-C_002b_002b" href="C_002b_002b-Misunderstandings.html#C_002b_002b-Misunderstandings">11.7 Common Misunderstandings with GNU C++</a>
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<li><a name="toc-Declare-and-Define-Static-Members" href="Static-Definitions.html#Static-Definitions">11.7.1 Declare <em>and</em> Define Static Members</a></li>
<li><a name="toc-Name-lookup_002c-templates_002c-and-accessing-members-of-base-classes" href="Name-lookup.html#Name-lookup">11.7.2 Name lookup, templates, and accessing members of base classes</a></li>
<li><a name="toc-Temporaries-May-Vanish-Before-You-Expect" href="Temporaries.html#Temporaries">11.7.3 Temporaries May Vanish Before You Expect</a></li>
<li><a name="toc-Implicit-Copy_002dAssignment-for-Virtual-Bases" href="Copy-Assignment.html#Copy-Assignment">11.7.4 Implicit Copy-Assignment for Virtual Bases</a></li>
</ul></li>
<li><a name="toc-Certain-Changes-We-Don_0027t-Want-to-Make" href="Non_002dbugs.html#Non_002dbugs">11.8 Certain Changes We Don&rsquo;t Want to Make</a></li>
<li><a name="toc-Warning-Messages-and-Error-Messages" href="Warnings-and-Errors.html#Warnings-and-Errors">11.9 Warning Messages and Error Messages</a></li>
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<li><a name="toc-Reporting-Bugs" href="Bugs.html#Bugs">12 Reporting Bugs</a>
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<li><a name="toc-Have-You-Found-a-Bug_003f" href="Bug-Criteria.html#Bug-Criteria">12.1 Have You Found a Bug?</a></li>
<li><a name="toc-How-and-where-to-Report-Bugs" href="Bug-Reporting.html#Bug-Reporting">12.2 How and where to Report Bugs</a></li>
</ul></li>
<li><a name="toc-How-To-Get-Help-with-GCC" href="Service.html#Service">13 How To Get Help with GCC</a></li>
<li><a name="toc-Contributing-to-GCC-Development" href="Contributing.html#Contributing">14 Contributing to GCC Development</a></li>
<li><a name="toc-Funding-Free-Software" href="Funding.html#Funding">Funding Free Software</a></li>
<li><a name="toc-The-GNU-Project-and-GNU_002fLinux" href="GNU-Project.html#GNU-Project">The GNU Project and GNU/Linux</a></li>
<li><a name="toc-GNU-General-Public-License" href="Copying.html#Copying">GNU General Public License</a></li>
<li><a name="toc-GNU-Free-Documentation-License-1" href="GNU-Free-Documentation-License.html#GNU-Free-Documentation-License">GNU Free Documentation License</a>
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<li><a name="toc-ADDENDUM_003a-How-to-use-this-License-for-your-documents" href="GNU-Free-Documentation-License.html#ADDENDUM_003a-How-to-use-this-License-for-your-documents">ADDENDUM: How to use this License for your documents</a></li>
</ul></li>
<li><a name="toc-Contributors-to-GCC" href="Contributors.html#Contributors">Contributors to GCC</a></li>
<li><a name="toc-Option-Index-1" href="Option-Index.html#Option-Index">Option Index</a></li>
<li><a name="toc-Keyword-Index-1" href="Keyword-Index.html#Keyword-Index">Keyword Index</a></li>
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<h1 class="top">Introduction</h1>
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<p>This manual documents how to use the GNU compilers,
as well as their features and incompatibilities, and how to report
bugs. It corresponds to the compilers
(Linaro GCC 4.9-2017.01)
version 4.9.4.
The internals of the GNU compilers, including how to port them to new
targets and some information about how to write front ends for new
languages, are documented in a separate manual. See <a href="http://gcc.gnu.org/onlinedocs/gccint/index.html#Top">Introduction</a> in <cite>GNU Compiler Collection (GCC) Internals</cite>.
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<tr><td align="left" valign="top">&bull; <a href="G_002b_002b-and-GCC.html#G_002b_002b-and-GCC" accesskey="1">G++ and GCC</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">You can compile C or C++ programs.
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<tr><td align="left" valign="top">&bull; <a href="Standards.html#Standards" accesskey="2">Standards</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Language standards supported by GCC.
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<tr><td align="left" valign="top">&bull; <a href="Invoking-GCC.html#Invoking-GCC" accesskey="3">Invoking GCC</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Command options supported by &lsquo;<samp>gcc</samp>&rsquo;.
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<tr><td align="left" valign="top">&bull; <a href="C-Implementation.html#C-Implementation" accesskey="4">C Implementation</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">How GCC implements the ISO C specification.
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<tr><td align="left" valign="top">&bull; <a href="C_002b_002b-Implementation.html#C_002b_002b-Implementation" accesskey="5">C++ Implementation</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">How GCC implements the ISO C++ specification.
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<tr><td align="left" valign="top">&bull; <a href="C-Extensions.html#C-Extensions" accesskey="6">C Extensions</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">GNU extensions to the C language family.
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<tr><td align="left" valign="top">&bull; <a href="Trouble.html#Trouble">Trouble</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">If you have trouble using GCC.
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</pre></th></tr><tr><td align="left" valign="top">&bull; <a href="Funding.html#Funding">Funding</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">How to help assure funding for free software.
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<tr><td align="left" valign="top">&bull; <a href="GNU-Project.html#GNU-Project">GNU Project</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">The GNU Project and GNU/Linux.
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<tr><th colspan="3" align="left" valign="top"><pre class="menu-comment">
</pre></th></tr><tr><td align="left" valign="top">&bull; <a href="Copying.html#Copying">Copying</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">GNU General Public License says
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<tr><td align="left" valign="top">&bull; <a href="GNU-Free-Documentation-License.html#GNU-Free-Documentation-License">GNU Free Documentation License</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">How you can copy and share this manual.
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</pre></th></tr><tr><td align="left" valign="top">&bull; <a href="Option-Index.html#Option-Index">Option Index</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Index to command line options.
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<tr><td align="left" valign="top">&bull; <a href="Keyword-Index.html#Keyword-Index">Keyword Index</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Index of concepts and symbol names.
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