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3 <html xmlns="http://www.w3.org/1999/xhtml"><head><title>Appendix B. Porting and Maintenance</title><meta name="generator" content="DocBook XSL-NS Stylesheets V1.76.1"/><meta name="keywords" content=" ISO C++ , library "/><meta name="keywords" content=" ISO C++ , runtime , library "/><link rel="home" href="../index.html" title="The GNU C++ Library"/><link rel="up" href="bk01pt04.html" title="Part IV. Appendices"/><link rel="prev" href="source_design_notes.html" title="Design Notes"/><link rel="next" href="documentation_hacking.html" title="Writing and Generating Documentation"/></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Appendix B.
4 Porting and Maintenance
6 </th></tr><tr><td align="left"><a accesskey="p" href="source_design_notes.html">Prev</a> </td><th width="60%" align="center">Part IV.
8 </th><td align="right"> <a accesskey="n" href="documentation_hacking.html">Next</a></td></tr></table><hr/></div><div class="appendix" title="Appendix B. Porting and Maintenance"><div class="titlepage"><div><div><h1 class="title"><a id="appendix.porting"/>
9 Porting and Maintenance
10 <a id="id660856" class="indexterm"/>
11 </h1></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl><dt><span class="section"><a href="appendix_porting.html#appendix.porting.build_hacking">Configure and Build Hacking</a></span></dt><dd><dl><dt><span class="section"><a href="appendix_porting.html#build_hacking.prereq">Prerequisites</a></span></dt><dt><span class="section"><a href="appendix_porting.html#build_hacking.map">Overview: What Comes from Where</a></span></dt><dt><span class="section"><a href="appendix_porting.html#build_hacking.scripts">Storing Information in non-AC files (like configure.host)</a></span></dt><dt><span class="section"><a href="appendix_porting.html#build_hacking.conventions">Coding and Commenting Conventions</a></span></dt><dt><span class="section"><a href="appendix_porting.html#build_hacking.acinclude">The acinclude.m4 layout</a></span></dt><dt><span class="section"><a href="appendix_porting.html#build_hacking.enable"><code class="constant">GLIBCXX_ENABLE</code>, the <code class="literal">--enable</code> maker</a></span></dt></dl></dd><dt><span class="section"><a href="documentation_hacking.html">Writing and Generating Documentation</a></span></dt><dd><dl><dt><span class="section"><a href="documentation_hacking.html#doc.intro">Introduction</a></span></dt><dt><span class="section"><a href="documentation_hacking.html#doc.generation">Generating Documentation</a></span></dt><dt><span class="section"><a href="documentation_hacking.html#doc.doxygen">Doxygen</a></span></dt><dd><dl><dt><span class="section"><a href="documentation_hacking.html#doxygen.prereq">Prerequisites</a></span></dt><dt><span class="section"><a href="documentation_hacking.html#doxygen.rules">Generating the Doxygen Files</a></span></dt><dt><span class="section"><a href="documentation_hacking.html#doxygen.markup">Markup</a></span></dt></dl></dd><dt><span class="section"><a href="documentation_hacking.html#doc.docbook">Docbook</a></span></dt><dd><dl><dt><span class="section"><a href="documentation_hacking.html#docbook.prereq">Prerequisites</a></span></dt><dt><span class="section"><a href="documentation_hacking.html#docbook.rules">Generating the DocBook Files</a></span></dt><dt><span class="section"><a href="documentation_hacking.html#docbook.validation">Editing and Validation</a></span></dt><dt><span class="section"><a href="documentation_hacking.html#docbook.examples">File Organization and Basics</a></span></dt><dt><span class="section"><a href="documentation_hacking.html#docbook.markup">Markup By Example</a></span></dt></dl></dd></dl></dd><dt><span class="section"><a href="internals.html">Porting to New Hardware or Operating Systems</a></span></dt><dd><dl><dt><span class="section"><a href="internals.html#internals.os">Operating System</a></span></dt><dt><span class="section"><a href="internals.html#internals.cpu">CPU</a></span></dt><dt><span class="section"><a href="internals.html#internals.char_types">Character Types</a></span></dt><dt><span class="section"><a href="internals.html#internals.thread_safety">Thread Safety</a></span></dt><dt><span class="section"><a href="internals.html#internals.numeric_limits">Numeric Limits</a></span></dt><dt><span class="section"><a href="internals.html#internals.libtool">Libtool</a></span></dt></dl></dd><dt><span class="section"><a href="test.html">Test</a></span></dt><dd><dl><dt><span class="section"><a href="test.html#test.organization">Organization</a></span></dt><dd><dl><dt><span class="section"><a href="test.html#test.organization.layout">Directory Layout</a></span></dt><dt><span class="section"><a href="test.html#test.organization.naming">Naming Conventions</a></span></dt></dl></dd><dt><span class="section"><a href="test.html#test.run">Running the Testsuite</a></span></dt><dd><dl><dt><span class="section"><a href="test.html#test.run.basic">Basic</a></span></dt><dt><span class="section"><a href="test.html#test.run.variations">Variations</a></span></dt><dt><span class="section"><a href="test.html#test.run.permutations">Permutations</a></span></dt></dl></dd><dt><span class="section"><a href="test.html#test.new_tests">Writing a new test case</a></span></dt><dt><span class="section"><a href="test.html#test.harness">Test Harness and Utilities</a></span></dt><dd><dl><dt><span class="section"><a href="test.html#test.harness.dejagnu">Dejagnu Harness Details</a></span></dt><dt><span class="section"><a href="test.html#test.harness.utils">Utilities</a></span></dt></dl></dd><dt><span class="section"><a href="test.html#test.special">Special Topics</a></span></dt><dd><dl><dt><span class="section"><a href="test.html#test.exception.safety">
12 Qualifying Exception Safety Guarantees
14 </a></span></dt><dd><dl><dt><span class="section"><a href="test.html#test.exception.safety.overview">Overview</a></span></dt><dt><span class="section"><a href="test.html#test.exception.safety.status">
16 </a></span></dt><dt><span class="section"><a href="test.html#test.exception.safety.containers">
17 C++11 Requirements Test Sequence Descriptions
18 </a></span></dt></dl></dd></dl></dd></dl></dd><dt><span class="section"><a href="abi.html">ABI Policy and Guidelines</a></span></dt><dd><dl><dt><span class="section"><a href="abi.html#abi.cxx_interface">The C++ Interface</a></span></dt><dt><span class="section"><a href="abi.html#abi.versioning">Versioning</a></span></dt><dd><dl><dt><span class="section"><a href="abi.html#abi.versioning.goals">Goals</a></span></dt><dt><span class="section"><a href="abi.html#abi.versioning.history">History</a></span></dt><dt><span class="section"><a href="abi.html#abi.versioning.prereq">Prerequisites</a></span></dt><dt><span class="section"><a href="abi.html#abi.versioning.config">Configuring</a></span></dt><dt><span class="section"><a href="abi.html#abi.versioning.active">Checking Active</a></span></dt></dl></dd><dt><span class="section"><a href="abi.html#abi.changes_allowed">Allowed Changes</a></span></dt><dt><span class="section"><a href="abi.html#abi.changes_no">Prohibited Changes</a></span></dt><dt><span class="section"><a href="abi.html#abi.impl">Implementation</a></span></dt><dt><span class="section"><a href="abi.html#abi.testing">Testing</a></span></dt><dd><dl><dt><span class="section"><a href="abi.html#abi.testing.single">Single ABI Testing</a></span></dt><dt><span class="section"><a href="abi.html#abi.testing.multi">Multiple ABI Testing</a></span></dt></dl></dd><dt><span class="section"><a href="abi.html#abi.issues">Outstanding Issues</a></span></dt></dl></dd><dt><span class="section"><a href="api.html">API Evolution and Deprecation History</a></span></dt><dd><dl><dt><span class="section"><a href="api.html#api.rel_300"><code class="constant">3.0</code></a></span></dt><dt><span class="section"><a href="api.html#api.rel_310"><code class="constant">3.1</code></a></span></dt><dt><span class="section"><a href="api.html#api.rel_320"><code class="constant">3.2</code></a></span></dt><dt><span class="section"><a href="api.html#api.rel_330"><code class="constant">3.3</code></a></span></dt><dt><span class="section"><a href="api.html#api.rel_340"><code class="constant">3.4</code></a></span></dt><dt><span class="section"><a href="api.html#api.rel_400"><code class="constant">4.0</code></a></span></dt><dt><span class="section"><a href="api.html#api.rel_410"><code class="constant">4.1</code></a></span></dt><dt><span class="section"><a href="api.html#api.rel_420"><code class="constant">4.2</code></a></span></dt><dt><span class="section"><a href="api.html#api.rel_430"><code class="constant">4.3</code></a></span></dt><dt><span class="section"><a href="api.html#api.rel_440"><code class="constant">4.4</code></a></span></dt><dt><span class="section"><a href="api.html#api.rel_450"><code class="constant">4.5</code></a></span></dt></dl></dd><dt><span class="section"><a href="backwards.html">Backwards Compatibility</a></span></dt><dd><dl><dt><span class="section"><a href="backwards.html#backwards.first">First</a></span></dt><dd><dl><dt><span class="section"><a href="backwards.html#backwards.first.ios_base">No <code class="code">ios_base</code></a></span></dt><dt><span class="section"><a href="backwards.html#backwards.first.cout_cin">No <code class="code">cout</code> in <code class="filename"><ostream.h></code>, no <code class="code">cin</code> in <code class="filename"><istream.h></code></a></span></dt></dl></dd><dt><span class="section"><a href="backwards.html#backwards.second">Second</a></span></dt><dd><dl><dt><span class="section"><a href="backwards.html#backwards.second.std">Namespace <code class="code">std::</code> not supported</a></span></dt><dt><span class="section"><a href="backwards.html#backwards.second.iterators">Illegal iterator usage</a></span></dt><dt><span class="section"><a href="backwards.html#backwards.second.isspace"><code class="code">isspace</code> from <code class="filename"><cctype></code> is a macro
19 </a></span></dt><dt><span class="section"><a href="backwards.html#backwards.second.at">No <code class="code">vector::at</code>, <code class="code">deque::at</code>, <code class="code">string::at</code></a></span></dt><dt><span class="section"><a href="backwards.html#backwards.second.eof">No <code class="code">std::char_traits<char>::eof</code></a></span></dt><dt><span class="section"><a href="backwards.html#backwards.second.stringclear">No <code class="code">string::clear</code></a></span></dt><dt><span class="section"><a href="backwards.html#backwards.second.ostreamform_istreamscan">
20 Removal of <code class="code">ostream::form</code> and <code class="code">istream::scan</code>
22 </a></span></dt><dt><span class="section"><a href="backwards.html#backwards.second.stringstreams">No <code class="code">basic_stringbuf</code>, <code class="code">basic_stringstream</code></a></span></dt><dt><span class="section"><a href="backwards.html#backwards.second.wchar">Little or no wide character support</a></span></dt><dt><span class="section"><a href="backwards.html#backwards.second.iostream_templates">No templatized iostreams</a></span></dt><dt><span class="section"><a href="backwards.html#backwards.second.thread_safety">Thread safety issues</a></span></dt></dl></dd><dt><span class="section"><a href="backwards.html#backwards.third">Third</a></span></dt><dd><dl><dt><span class="section"><a href="backwards.html#backwards.third.headers">Pre-ISO headers moved to backwards or removed</a></span></dt><dt><span class="section"><a href="backwards.html#backwards.third.hash">Extension headers hash_map, hash_set moved to ext or backwards</a></span></dt><dt><span class="section"><a href="backwards.html#backwards.third.nocreate_noreplace">No <code class="code">ios::nocreate/ios::noreplace</code>.
23 </a></span></dt><dt><span class="section"><a href="backwards.html#backwards.third.streamattach">
24 No <code class="code">stream::attach(int fd)</code>
25 </a></span></dt><dt><span class="section"><a href="backwards.html#backwards.third.support_cxx98">
26 Support for C++98 dialect.
27 </a></span></dt><dt><span class="section"><a href="backwards.html#backwards.third.support_tr1">
28 Support for C++TR1 dialect.
29 </a></span></dt><dt><span class="section"><a href="backwards.html#backwards.third.support_cxx11">
30 Support for C++11 dialect.
31 </a></span></dt><dt><span class="section"><a href="backwards.html#backwards.third.iterator_type">
32 <code class="code">Container::iterator_type</code> is not necessarily <code class="code">Container::value_type*</code>
33 </a></span></dt></dl></dd></dl></dd></dl></div><div class="section" title="Configure and Build Hacking"><div class="titlepage"><div><div><h2 class="title"><a id="appendix.porting.build_hacking"/>Configure and Build Hacking</h2></div></div></div><div class="section" title="Prerequisites"><div class="titlepage"><div><div><h3 class="title"><a id="build_hacking.prereq"/>Prerequisites</h3></div></div></div><p>
34 As noted <a class="link" href="http://gcc.gnu.org/install/prerequisites.html">previously</a>,
35 certain other tools are necessary for hacking on files that
36 control configure (<code class="code">configure.ac</code>,
37 <code class="code">acinclude.m4</code>) and make
38 (<code class="code">Makefile.am</code>). These additional tools
39 (<code class="code">automake</code>, and <code class="code">autoconf</code>) are further
40 described in detail in their respective manuals. All the libraries
41 in GCC try to stay in sync with each other in terms of versions of
42 the auto-tools used, so please try to play nicely with the
44 </p></div><div class="section" title="Overview: What Comes from Where"><div class="titlepage"><div><div><h3 class="title"><a id="build_hacking.map"/>Overview: What Comes from Where</h3></div></div></div><div class="figure"><a id="id660988"/><p class="title"><strong>Figure B.1. Configure and Build File Dependencies</strong></p><div class="figure-contents"><div class="mediaobject" style="text-align: center"><img src="../images/confdeps.png" style="text-align: middle" alt="Dependency Graph for Configure and Build Files"/></div></div></div><br class="figure-break"/><p>
45 Regenerate all generated files by using the command sequence
46 <code class="code">"autoreconf"</code> at the top level of the libstdc++ source
47 directory. The following will also work, but is much more complex:
48 <code class="code">"aclocal-1.11 && autoconf-2.64 &&
49 autoheader-2.64 && automake-1.11"</code> The version
50 numbers may be absent entirely or otherwise vary depending on
51 <a class="link" href="http://gcc.gnu.org/install/prerequisites.html">the
52 current requirements</a> and your vendor's choice of
54 </p></div><div class="section" title="Storing Information in non-AC files (like configure.host)"><div class="titlepage"><div><div><h3 class="title"><a id="build_hacking.scripts"/>Storing Information in non-AC files (like configure.host)</h3></div></div></div><p>
55 Until that glorious day when we can use AC_TRY_LINK with a
56 cross-compiler, we have to hardcode the results of what the tests
57 would have shown if they could be run. So we have an inflexible
58 mess like crossconfig.m4.
60 Wouldn't it be nice if we could store that information in files
61 like configure.host, which can be modified without needing to
62 regenerate anything, and can even be tweaked without really
63 knowing how the configury all works? Perhaps break the pieces of
64 crossconfig.m4 out and place them in their appropriate
65 config/{cpu,os} directory.
67 Alas, writing macros like
68 "<code class="code">AC_DEFINE(HAVE_A_NICE_DAY)</code>" can only be done inside
69 files which are passed through autoconf. Files which are pure
70 shell script can be source'd at configure time. Files which
71 contain autoconf macros must be processed with autoconf. We could
72 still try breaking the pieces out into "config/*/cross.m4" bits,
73 for instance, but then we would need arguments to aclocal/autoconf
74 to properly find them all when generating configure. I would
76 </p></div><div class="section" title="Coding and Commenting Conventions"><div class="titlepage"><div><div><h3 class="title"><a id="build_hacking.conventions"/>Coding and Commenting Conventions</h3></div></div></div><p>
77 Most comments should use {octothorpes, shibboleths, hash marks,
78 pound signs, whatever} rather than "dnl". Nearly all comments in
79 configure.ac should. Comments inside macros written in ancilliary
80 .m4 files should. About the only comments which should
81 <span class="emphasis"><em>not</em></span> use #, but use dnl instead, are comments
82 <span class="emphasis"><em>outside</em></span> our own macros in the ancilliary
83 files. The difference is that # comments show up in
84 <code class="code">configure</code> (which is most helpful for debugging),
85 while dnl'd lines just vanish. Since the macros in ancilliary
86 files generate code which appears in odd places, their "outside"
87 comments tend to not be useful while reading
88 <code class="code">configure</code>.
90 Do not use any <code class="code">$target*</code> variables, such as
91 <code class="code">$target_alias</code>. The single exception is in
92 configure.ac, for automake+dejagnu's sake.
93 </p></div><div class="section" title="The acinclude.m4 layout"><div class="titlepage"><div><div><h3 class="title"><a id="build_hacking.acinclude"/>The acinclude.m4 layout</h3></div></div></div><p>
94 The nice thing about acinclude.m4/aclocal.m4 is that macros aren't
95 actually performed/called/expanded/whatever here, just loaded. So
96 we can arrange the contents however we like. As of this writing,
97 acinclude.m4 is arranged as follows:
98 </p><pre class="programlisting">
100 GLIBCXX_TOPREL_CONFIGURE
103 All the major variable "discovery" is done here. CXX, multilibs,
105 </p><pre class="programlisting">
106 fragments included from elsewhere
108 Right now, "fragments" == "the math/linkage bits".
109 </p><pre class="programlisting">
110 GLIBCXX_CHECK_COMPILER_FEATURES
111 GLIBCXX_CHECK_LINKER_FEATURES
112 GLIBCXX_CHECK_WCHAR_T_SUPPORT
114 Next come extra compiler/linker feature tests. Wide character
115 support was placed here because I couldn't think of another place
116 for it. It will probably get broken apart like the math tests,
117 because we're still disabling wchars on systems which could actually
119 </p><pre class="programlisting">
120 GLIBCXX_CHECK_SETRLIMIT_ancilliary
121 GLIBCXX_CHECK_SETRLIMIT
122 GLIBCXX_CHECK_S_ISREG_OR_S_IFREG
126 GLIBCXX_CONFIGURE_TESTSUITE
128 Feature tests which only get used in one place. Here, things used
129 only in the testsuite, plus a couple bits used in the guts of I/O.
130 </p><pre class="programlisting">
131 GLIBCXX_EXPORT_INCLUDES
133 GLIBCXX_EXPORT_INSTALL_INFO
135 Installation variables, multilibs, working with the rest of the
136 compiler. Many of the critical variables used in the makefiles are
138 </p><pre class="programlisting">
141 GLIBCXX_ENABLE_CHEADERS
142 GLIBCXX_ENABLE_CLOCALE
143 GLIBCXX_ENABLE_CONCEPT_CHECKS
144 GLIBCXX_ENABLE_CSTDIO
145 GLIBCXX_ENABLE_CXX_FLAGS
146 GLIBCXX_ENABLE_C_MBCHAR
148 GLIBCXX_ENABLE_DEBUG_FLAGS
149 GLIBCXX_ENABLE_LONG_LONG
151 GLIBCXX_ENABLE_SJLJ_EXCEPTIONS
152 GLIBCXX_ENABLE_SYMVERS
153 GLIBCXX_ENABLE_THREADS
155 All the features which can be controlled with enable/disable
156 configure options. Note how they're alphabetized now? Keep them
158 </p><pre class="programlisting">
162 Things which we don't seem to use directly, but just has to be
163 present otherwise stuff magically goes wonky.
164 </p></div><div class="section" title="GLIBCXX_ENABLE, the --enable maker"><div class="titlepage"><div><div><h3 class="title"><a id="build_hacking.enable"/><code class="constant">GLIBCXX_ENABLE</code>, the <code class="literal">--enable</code> maker</h3></div></div></div><p>
165 All the GLIBCXX_ENABLE_FOO macros use a common helper,
166 GLIBCXX_ENABLE. (You don't have to use it, but it's easy.) The
167 helper does two things for us:
168 </p><div class="orderedlist"><ol class="orderedlist"><li class="listitem"><p>
169 Builds the call to the AC_ARG_ENABLE macro, with --help text
170 properly quoted and aligned. (Death to changequote!)
171 </p></li><li class="listitem"><p>
172 Checks the result against a list of allowed possibilities, and
173 signals a fatal error if there's no match. This means that the
174 rest of the GLIBCXX_ENABLE_FOO macro doesn't need to test for
175 strange arguments, nor do we need to protect against
176 empty/whitespace strings with the <code class="code">"x$foo" = "xbar"</code>
178 </p></li></ol></div><p>Doing these things correctly takes some extra autoconf/autom4te code,
179 which made our macros nearly illegible. So all the ugliness is factored
180 out into this one helper macro.
181 </p><p>Many of the macros take an argument, passed from when they are expanded
182 in configure.ac. The argument controls the default value of the
183 enable/disable switch. Previously, the arguments themselves had defaults.
184 Now they don't, because that's extra complexity with zero gain for us.
185 </p><p>There are three "overloaded signatures". When reading the descriptions
186 below, keep in mind that the brackets are autoconf's quotation characters,
187 and that they will be stripped. Examples of just about everything occur
188 in acinclude.m4, if you want to look.
189 </p><pre class="programlisting">
190 GLIBCXX_ENABLE (FEATURE, DEFAULT, HELP-ARG, HELP-STRING)
191 GLIBCXX_ENABLE (FEATURE, DEFAULT, HELP-ARG, HELP-STRING, permit a|b|c)
192 GLIBCXX_ENABLE (FEATURE, DEFAULT, HELP-ARG, HELP-STRING, SHELL-CODE-HANDLER)
193 </pre><div class="itemizedlist"><ul class="itemizedlist"><li class="listitem"><p>
194 FEATURE is the string that follows --enable. The results of the
195 test (such as it is) will be in the variable $enable_FEATURE,
196 where FEATURE has been squashed. Example:
197 <code class="code">[extra-foo]</code>, controlled by the --enable-extra-foo
198 option and stored in $enable_extra_foo.
199 </p></li><li class="listitem"><p>
200 DEFAULT is the value to store in $enable_FEATURE if the user does
201 not pass --enable/--disable. It should be one of the permitted
202 values passed later. Examples: <code class="code">[yes]</code>, or
203 <code class="code">[bar]</code>, or <code class="code">[$1]</code> (which passes the
204 argument given to the GLIBCXX_ENABLE_FOO macro as the
207 For cases where we need to probe for particular models of things,
208 it is useful to have an undocumented "auto" value here (see
209 GLIBCXX_ENABLE_CLOCALE for an example).
210 </p></li><li class="listitem"><p>
211 HELP-ARG is any text to append to the option string itself in the
212 --help output. Examples: <code class="code">[]</code> (i.e., an empty string,
213 which appends nothing), <code class="code">[=BAR]</code>, which produces
214 <code class="code">--enable-extra-foo=BAR</code>, and
215 <code class="code">[@<:@=BAR@:>@]</code>, which produces
216 <code class="code">--enable-extra-foo[=BAR]</code>. See the difference? See
217 what it implies to the user?
219 If you're wondering what that line noise in the last example was,
220 that's how you embed autoconf special characters in output text.
221 They're called <a class="link" href="http://www.gnu.org/software/autoconf/manual/autoconf.html#Quadrigraphs"><span class="emphasis"><em>quadrigraphs</em></span></a>
222 and you should use them whenever necessary.
223 </p></li><li class="listitem"><p>HELP-STRING is what you think it is. Do not include the
224 "default" text like we used to do; it will be done for you by
225 GLIBCXX_ENABLE. By convention, these are not full English
226 sentences. Example: [turn on extra foo]
227 </p></li></ul></div><p>
228 With no other arguments, only the standard autoconf patterns are
229 allowed: "<code class="code">--{enable,disable}-foo[={yes,no}]</code>" The
230 $enable_FEATURE variable is guaranteed to equal either "yes" or "no"
231 after the macro. If the user tries to pass something else, an
232 explanatory error message will be given, and configure will halt.
234 The second signature takes a fifth argument, "<code class="code">[permit
235 a | b | c | ...]</code>"
236 This allows <span class="emphasis"><em>a</em></span> or <span class="emphasis"><em>b</em></span> or
237 ... after the equals sign in the option, and $enable_FEATURE is
238 guaranteed to equal one of them after the macro. Note that if you
239 want to allow plain --enable/--disable with no "=whatever", you must
240 include "yes" and "no" in the list of permitted values. Also note
241 that whatever you passed as DEFAULT must be in the list. If the
242 user tries to pass something not on the list, a semi-explanatory
243 error message will be given, and configure will halt. Example:
244 <code class="code">[permit generic|gnu|ieee_1003.1-2001|yes|no|auto]</code>
246 The third signature takes a fifth argument. It is arbitrary shell
247 code to execute if the user actually passes the enable/disable
248 option. (If the user does not, the default is used. Duh.) No
249 argument checking at all is done in this signature. See
250 GLIBCXX_ENABLE_CXX_FLAGS for an example of handling, and an error
252 </p></div></div></div><div class="navfooter"><hr/><table width="100%" summary="Navigation footer"><tr><td align="left"><a accesskey="p" href="source_design_notes.html">Prev</a> </td><td align="center"><a accesskey="u" href="bk01pt04.html">Up</a></td><td align="right"> <a accesskey="n" href="documentation_hacking.html">Next</a></td></tr><tr><td align="left" valign="top">Design Notes </td><td align="center"><a accesskey="h" href="../index.html">Home</a></td><td align="right" valign="top"> Writing and Generating Documentation</td></tr></table></div></body></html>
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