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| 3 | <head>
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| 4 | <title>GCC Frequently Asked Questions</title>
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| 5 | </head>
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| 6 |
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| 7 | <body>
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| 8 |
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| 9 | <h1>GCC Frequently Asked Questions</h1>
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| 10 |
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| 11 | <p>The latest version of this document is always available at
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| 12 | <a href="http://www.gnu.org/software/gcc/faq.html">http://www.gnu.org/software/gcc/faq.html</a>.</p>
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| 13 |
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| 14 | <p>This FAQ tries to answer specific questions concerning GCC. For
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| 15 | general information regarding C, C++, resp. Fortran please check the
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| 16 | <a href="http://www.eskimo.com/~scs/C-faq/top.html">comp.lang.c FAQ</a>,
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| 17 | <a href="http://www.research.att.com/~austern/csc/faq.html">comp.std.c++
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| 18 | FAQ</a>,
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| 19 | and the <a href="http://www.fortran.com/fortran/info.html">Fortran
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| 20 | Information page</a>.</p>
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| 21 |
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| 22 | <p>Other GCC-related FAQs:
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| 23 | <a href="http://gcc.gnu.org/onlinedocs/libstdc++/faq/index.html">
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| 24 | libstdc++-v3</a>, and
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| 25 | <a href="http://gcc.gnu.org/java/faq.html">GCJ</a>.</p>
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| 26 |
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| 27 | <hr />
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| 28 | <h1>Questions</h1>
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| 29 | <ol>
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| 30 | <li><a href="#general">General information</a>
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| 31 | <ol>
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| 32 | <li><a href="#gcc">What is the relationship between GCC and EGCS?</a></li>
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| 33 | <li><a href="#cygnus">What is the relationship between GCC and Cygnus / Red Hat?</a></li>
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| 34 | <li><a href="#open-development">What is an open development model?</a></li>
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| 35 | <li><a href="#bugreport">How do I report a bug?</a></li>
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| 36 | <li><a href="#support">How do I get a bug fixed or a feature added?</a></li>
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| 37 | <li><a href="#platforms">Does GCC work on my platform?</a></li>
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| 38 | </ol></li>
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| 39 |
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| 40 | <li><a href="#installation">Installation</a>
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| 41 | <ol>
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| 42 | <li><a href="#multiple">How to install multiple versions of GCC</a></li>
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| 43 | <li><a href="#rpath">Dynamic linker is unable to find GCC libraries</a></li>
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| 44 | <li><a href="#rpath">libstdc++/libio tests fail badly with --enable-shared</a></li>
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| 45 | <li><a href="#gas">GCC can not find GNU as/GNU ld</a></li>
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| 46 | <li><a href="#environ">cpp: Usage:... Error</a></li>
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| 47 | <li><a href="#optimizing">Optimizing the compiler itself</a></li>
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| 48 | </ol></li>
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| 49 |
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| 50 | <li><a href="#testsuite">Testsuite problems</a>
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| 51 | <ol>
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| 52 | <li><a href="#dejagnu">Unable to run the testsuite</a></li>
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| 53 | <li><a href="#testoptions">How do I pass flags like
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| 54 | <code>-fnew-abi</code> to the testsuite?</a></li>
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| 55 | <li><a href="#multipletests">How can I run the test suite with multiple options?</a></li>
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| 56 | </ol></li>
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| 57 |
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| 58 | <li><a href="#old">Older versions of GCC</a>
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| 59 | <ol>
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| 60 | <li><a href="#2.95sstream">Is there a stringstream / sstream for GCC 2.95.2?</a></li>
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| 61 | </ol></li>
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| 62 |
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| 63 | <li><a href="#misc">Miscellaneous</a>
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| 64 | <ol>
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| 65 | <li><a href="#friend">Friend Templates</a></li>
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| 66 | <li><a href="#dso"><code>dynamic_cast</code>, <code>throw</code>, <code>typeid</code> don't work with shared libraries</a></li>
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| 67 | <li><a href="#generated_files">Why do I need autoconf, bison, xgettext, automake, etc?</a></li>
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| 68 | <li><a href="#picflag-needed">Why can't I build a shared library?</a></li>
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| 69 | <li><a href="#vtables">When building C++, the linker says my constructors, destructors or virtual tables are undefined, but I defined them</a></li>
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| 70 | <li><a href="#incremental">Will GCC someday include an incremental linker?</a></li>
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| 71 | </ol></li>
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| 72 | </ol>
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| 73 |
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| 74 |
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| 75 | <hr />
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| 76 | <a name="general"></a>
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| 77 | <h1>General information</h1>
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| 78 |
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| 79 | <h2><a name="gcc">What is the relationship between GCC and EGCS?</a></h2>
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| 80 |
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| 81 | <p>In 1990/1991 gcc version 1 had reached a point of stability. For the
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| 82 | targets it could support, it worked well. It had limitations inherent in
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| 83 | its design that would be difficult to resolve, so a major effort was made
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| 84 | to resolve those limitiations and gcc version 2 was the result.</p>
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| 85 |
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| 86 | <p>When we had gcc2 in a useful state, development efforts on gcc1 stopped
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| 87 | and we all concentrated on making gcc2 better than gcc1 could ever be. This
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| 88 | is the kind of step forward we wanted to make with the EGCS project when it
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| 89 | was formed in 1997.</p>
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| 90 |
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| 91 | <p>In April 1999 the Free Software Foundation officially halted
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| 92 | development on the gcc2 compiler and appointed the EGCS project as the
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| 93 | official GCC maintainers. The net result was a single project which
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| 94 | carries forward GCC development under the ultimate control of the
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| 95 | <a href="steering.html">GCC Steering Committee</a>.</p>
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| 96 |
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| 97 |
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| 98 | <hr />
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| 99 | <h2><a name="cygnus">What is the relationship between GCC and Cygnus / Red Hat?</a></h2>
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| 100 |
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| 101 | <p>It is a common mis-conception that Red Hat controls GCC either
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| 102 | directly or indirectly.</p>
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| 103 |
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| 104 | <p>While Red Hat does donate hardware, network connections, code and
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| 105 | developer time to GCC development, Red Hat does not control GCC.</p>
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| 106 |
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| 107 | <p>Overall control of GCC is in the hands of the
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| 108 | <a href="steering.html">GCC Steering Committee</a>
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| 109 | which includes people from a variety of different organizations and
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| 110 | backgrounds. The purpose of the steering committee is to make
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| 111 | decisions in the best interest of GCC and to help ensure that no
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| 112 | individual or company has control over the project.</p>
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| 113 |
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| 114 | <p>To summarize, Red Hat contributes to the GCC project, but does not exert
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| 115 | a controlling influence over GCC.</p>
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| 116 |
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| 117 | <hr />
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| 118 | <h2><a name="open-development">What is an open development model?</a></h2>
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| 119 |
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| 120 | <p>We are using a bazaar style
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| 121 | <a href="#cathedral-vs-bazaar"><b>[1]</b></a>
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| 122 | approach to GCC development: we make snapshots publicly available to
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| 123 | anyone who wants to try them; we welcome anyone to join
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| 124 | the development mailing list. All of the discussions on the
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| 125 | development mailing list are available via the web. We're going to be
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| 126 | making releases with a much higher frequency than they have been made
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| 127 | in the past.</p>
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| 128 |
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| 129 | <p>In addition to weekly snapshots of the GCC development sources, we
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| 130 | have the sources readable from a CVS server by anyone. Furthermore we
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| 131 | are using remote CVS to allow remote maintainers write access to the
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| 132 | sources.</p>
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| 133 |
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| 134 | <p>There have been many potential GCC developers who were not able to
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| 135 | participate in GCC development in the past. We want these people to
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| 136 | help in any way they can; we ultimately want GCC to be the best compiler
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| 137 | in the world.</p>
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| 138 |
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| 139 | <p>A compiler is a complicated piece of software, there will still be
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| 140 | strong central maintainers who will reject patches, who will demand
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| 141 | documentation of implementations, and who will keep the level of
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| 142 | quality as high as it is today. Code that could use wider testing may
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| 143 | be integrated--code that is simply ill-conceived won't be.</p>
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| 144 |
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| 145 | <p>GCC is not the first piece of software to use this open development
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| 146 | process; FreeBSD, the Emacs lisp repository, and the Linux kernel are
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| 147 | a few examples of the bazaar style of development.</p>
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| 148 |
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| 149 | <p>With GCC, we are adding new features and optimizations at a
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| 150 | rate that has not been done since the creation of gcc2; these
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| 151 | additions inevitably have a temporarily destabilizing effect.
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| 152 | With the help of developers working together with this bazaar style
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| 153 | development, the resulting stability and quality levels will be better
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| 154 | than we've had before.</p>
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| 155 |
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| 156 | <blockquote>
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| 157 | <a name="cathedral-vs-bazaar"><b>[1]</b></a>
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| 158 | We've been discussing different development models a lot over the
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| 159 | past few months. The paper which started all of this introduced two
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| 160 | terms: A <b>cathedral</b> development model versus a <b>bazaar</b>
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| 161 | development model. The paper is written by Eric S. Raymond, it is
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| 162 | called ``<a
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| 163 | href="http://www.tuxedo.org/~esr/writings/cathedral-bazaar/">The
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| 164 | Cathedral and the Bazaar</a>''. The paper is a useful starting point
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| 165 | for discussions.
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| 166 | </blockquote>
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| 167 |
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| 168 |
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| 169 | <hr />
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| 170 | <h2><a name="bugreport">How do I report a bug?</a></h2>
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| 171 |
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| 172 | <p>There are complete instructions <a href="bugs.html">here</a>.</p>
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| 173 |
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| 174 |
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| 175 | <hr />
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| 176 | <h2><a name="support">How do I get a bug fixed or a feature added?</a></h2>
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| 177 |
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| 178 | <p>There are lots of ways to get something fixed. The list below may be
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| 179 | incomplete, but it covers many of the common cases. These are listed
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| 180 | roughly in order of increasing difficulty for the average GCC user,
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| 181 | meaning someone who is not skilled in the internals of GCC, and where
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| 182 | difficulty is measured in terms of the time required to fix the bug.
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| 183 | No alternative is better than any other; each has its benefits and
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| 184 | disadvantages.</p>
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| 185 |
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| 186 | <ul>
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| 187 | <li>Hire someone to fix it for you. There are various companies and
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| 188 | individuals providing support for GCC. This alternative costs
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| 189 | money, but is relatively likely to get results.</li>
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| 190 |
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| 191 | <li><a href="bugs.html">Report the problem to the GCC GNATS bug tracking system</a>
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| 192 | and hope that someone will be kind
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| 193 | enough to fix it for you. While this is certainly possible, and
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| 194 | often happens, there is no guarantee that it will. You should
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| 195 | not expect the same response from this method that you would see
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| 196 | from a commercial support organization since the people who read
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| 197 | GCC bug reports, if they choose to help you, will be volunteering their
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| 198 | time. This alternative will work best if you follow the directions
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| 199 | on <a href="bugs.html">submitting bugreports</a>.</li>
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| 200 |
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| 201 | <li>Fix it yourself. This alternative will probably bring results,
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| 202 | if you work hard enough, but will probably take a lot of time,
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| 203 | and, depending on the quality of your work and the perceived
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| 204 | benefits of your changes, your code may or may not ever make it
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| 205 | into an official release of GCC.</li>
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| 206 | </ul>
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| 207 |
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| 208 | <hr />
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| 209 |
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| 210 | <h2><a name="platforms">Does GCC work on my platform?</a></h2>
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| 211 |
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| 212 | <p>The host/target specific installation notes for GCC include information
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| 213 | about known problems with installing or using GCC on particular platforms.
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| 214 | These are included in the sources for a release in INSTALL/specific.html,
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| 215 | and the <a href="http://gcc.gnu.org/install/specific.html">latest version</a>
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| 216 | is always available at the GCC web site.
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| 217 | Reports of <a href="http://gcc.gnu.org/buildstat.html">successful builds</a>
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| 218 | for several versions of GCC are also available at the web site.</p>
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| 219 |
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| 220 | <hr />
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| 221 | <a name="installation"></a>
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| 222 | <h1>Installation</h1>
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| 223 |
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| 224 | <h2><a name="multiple">How to install multiple versions of GCC</a></h2>
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| 225 |
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| 226 | <p>It may be desirable to install multiple versions of the compiler on
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| 227 | the same system. This can be done by using different prefix paths at
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| 228 | configure time and a few symlinks.</p>
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| 229 |
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| 230 | <p>Basically, configure the two compilers with different --prefix options,
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| 231 | then build and install each compiler. Assume you want "gcc" to be the latest
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| 232 | compiler and available in /usr/local/bin; also assume that you want "gcc2"
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| 233 | to be the older gcc2 compiler and also available in /usr/local/bin.</p>
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