Red Hat Enterprise Linux 3 Using the GNU Compiler Collection (GCC) Red Hat Enterprise Linux 3: Using the GNU Compiler Collection (GCC) Copyright © 1987, 1989, 1991-2003 by Free Software Foundation, Inc. Copyright © 2003 by Red Hat, Inc. Copyright © 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003 Free Software Foundation, Inc. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with the Invariant Sections being "GNU General Public License" and "Funding Free Software", 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 "GNU Free Documentation License". 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. 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All other trademarks and copyrights referred to are the property of their respective owners. HTML, PDF, and RPM versions of the manuals are available on the Documentation CD and online at http://www.redhat.com/docs/. The GPG fingerprint of the [email protected] key is: CA 20 86 86 2B D6 9D FC 65 F6 EC C4 21 91 80 CD DB 42 A6 0E Table of Contents 1. Introduction..................................................................................................................................... 1 2. Compile C, C++, Objective-C, Ada, Fortran, Java, or treelang ................................................. 3 3. Language Standards Supported by GCC..................................................................................... 5 4. GCC Command Options ................................................................................................................ 7 4.1. Option Summary................................................................................................................ 7 4.2. Options Controlling the Kind of Output .......................................................................... 12 4.3. Compiling C++ Programs................................................................................................ 15 4.4. Options Controlling C Dialect ......................................................................................... 15 4.5. Options Controlling C++ Dialect..................................................................................... 19 4.6. Options Controlling Objective-C Dialect ........................................................................ 25 4.7. Options to Control Diagnostic Messages Formatting...................................................... 26 4.8. Options to Request or Suppress Warnings....................................................................... 26 4.9. Options for Debugging Your Program or GCC ............................................................... 38 4.10. Options That Control Optimization ............................................................................... 47 4.11. Options Controlling the Preprocessor............................................................................ 64 4.12. Passing Options to the Assembler.................................................................................. 72 4.13. Options for Linking........................................................................................................ 72 4.14. Options for Directory Search......................................................................................... 75 4.15. Specifying subprocesses and the switches to pass to them............................................ 76 4.16. Specifying Target Machine and Compiler Version ........................................................ 83 4.17. Hardware Models and Configurations ........................................................................... 83 4.17.1. SPARC Options............................................................................................... 84 4.17.2. IBM RS/6000 and PowerPC Options ............................................................. 87 4.17.3. Intel 386 and AMD x86-64 Options ............................................................... 95 4.17.4. IA-64 Options ............................................................................................... 100 4.17.5. S/390 and zSeries Options ............................................................................ 102 4.18. Options for Code Generation Conventions.................................................................. 103 4.19. Environment Variables Affecting GCC ....................................................................... 108 4.20. Using Precompiled Headers......................................................................................... 110 4.21. Running Protoize ......................................................................................................... 111 5. C Implementation-defined behavior ......................................................................................... 115 5.1. Translation ..................................................................................................................... 115 5.2. Environment................................................................................................................... 115 5.3. Identifiers ....................................................................................................................... 115 5.4. Characters ...................................................................................................................... 115 5.5. Integers........................................................................................................................... 116 5.6. Floating point................................................................................................................. 116 5.7. Arrays and pointers........................................................................................................ 117 5.8. Hints............................................................................................................................... 117 5.9. Structures, unions, enumerations, and bit-fields ............................................................ 117 5.10. Qualifiers...................................................................................................................... 118 5.11. Preprocessing directives............................................................................................... 118 5.12. Library functions.......................................................................................................... 118 5.13. Architecture.................................................................................................................. 118 5.14. Locale-specific behavior .............................................................................................. 119 6. Extensions to the C Language Family....................................................................................... 121 6.1. Statements and Declarations in Expressions.................................................................. 121 6.2. Locally Declared Labels ................................................................................................ 122 6.3. Labels as Values............................................................................................................. 122 6.4. Nested Functions............................................................................................................ 123 6.5. Constructing Function Calls .......................................................................................... 125 6.6. Referring to a Type with typeof .................................................................................. 125 6.7. Generalized Lvalues....................................................................................................... 127 6.8. Conditionals with Omitted Operands............................................................................. 128 6.9. Double-Word Integers.................................................................................................... 128 6.10. Complex Numbers ....................................................................................................... 128 6.11. Hex Floats .................................................................................................................... 129 6.12. Arrays of Length Zero ................................................................................................