[wwwdocs] [PATCH] Add "id" attributes to the headings in the GCC 6 porting guide

[David Malcolm <dmalcolm at redhat dot com>]

htdocs/gcc-6/porting_to.html is now multiple screens of text.

The attached patch adds "id" attributes to every h2, h3 and h4 element
in the page, so that people can create URLs that reference specific
subsections of the guide.

Validates.

OK to commit?

Index: htdocs/gcc-6/porting_to.html
===================================================================
RCS file: /cvs/gcc/wwwdocs/htdocs/gcc-6/porting_to.html,v
retrieving revision 1.19
diff -u -p -r1.19 porting_to.html
--- htdocs/gcc-6/porting_to.html	1 Mar 2016 19:22:05 -0000	1.19
+++ htdocs/gcc-6/porting_to.html	1 Mar 2016 19:36:49 -0000
@@ -25,15 +25,15 @@ manner. Additions and suggestions for im
 </p>
 
 
-<h2>Preprocessor issues</h2>
+<h2 id="cpp">Preprocessor issues</h2>
 
 
-<h2>C language issues</h2>
+<h2 id="c">C language issues</h2>
 
 
-<h2>C++ language issues</h2>
+<h2 id="cp">C++ language issues</h2>
 
-<h3>Default standard is now GNU++14</h3>
+<h3 id="gnu-plus-plus-14">Default standard is now GNU++14</h3>
 
 <p>
 GCC 6 defaults to <code>-std=gnu++14</code> instead of <code>-std=gnu++98</code>:
@@ -51,7 +51,7 @@ in <code>CXXFLAGS</code> or similar vari
 changes but not the C++14 ones.  If so, use the <code>-std=gnu++11</code>
 command-line option.</p>
 
-<h4>Narrowing conversions</h4>
+<h4 id="narrowing-conversions">Narrowing conversions</h4>
 
 <p>
 The C++11 standard does not allow "narrowing conversions" inside braced
@@ -71,7 +71,7 @@ conversion. Narrowing conversions can be
 e.g. <code>(char)i</code>.
 </p>
 
-<h4>Invalid literal suffixes</h4>
+<h4 id="invalid-literal-suffixes">Invalid literal suffixes</h4>
 
 <p>
 The C++11 "user-defined literals" feature allows custom suffixes to be added
@@ -84,7 +84,7 @@ the code to compile in C++11 add whitesp
 macro: <code>printf("%" PRIu64, uint64_value)</code>.
 </p>
 
-<h4>Cannot convert 'bool' to 'T*'</h4>
+<h4 id="null-pointer-constants">Cannot convert 'bool' to 'T*'</h4>
 
 <p>
 The current C++ standard only allows integer literals to be used as null
@@ -94,7 +94,7 @@ fails to compile with this error should 
 or <code>0</code>, or <code>NULL</code>.
 </p>
 
-<h4>Cannot convert 'std::ostream' to 'bool'</h4>
+<h4 id="iostream-conversions">Cannot convert 'std::ostream' to 'bool'</h4>
 
 <p>
 As of C++11, iostream classes are no longer implicitly convertible to
@@ -111,7 +111,7 @@ or
 <code>return static_cast&lt;bool&gt;(os);</code>
 </p>
 
-<h4>Lvalue required as left operand of assignment with complex numbers</h4>
+<h4 id="complex-lvalues">Lvalue required as left operand of assignment with complex numbers</h4>
 
 <p>
 Since C++11 (as per DR#387) the member functions <code>real()</code> and 
@@ -132,7 +132,7 @@ following should be used instead:
   f.real (val);
 </code></pre>
 
-<h4>Destructors are <code>noexcept</code> by default</h4>
+<h4 id="dtors-default-to-noexcept">Destructors are <code>noexcept</code> by default</h4>
 
 <p>
 As of C++11, destructors have an implicit <code>noexcept</code>
@@ -168,7 +168,7 @@ behavior when defining the destructor li
     ~S() noexcept(false) { throw std::runtime_error ("oops"); }
 </code></pre>
 
-<h3>Header dependency changes</h3>
+<h3 id="header-dep-changes">Header dependency changes</h3>
 
 <p>
 The <code>&lt;algorithm&gt;</code> header has been changed to reduce the
@@ -179,7 +179,7 @@ As such, C++ programs that used componen
 will no longer compile.
 </p>
 
-<h3>Header <code>&lt;cmath&gt;</code> changes</h3>
+<h3 id="cmath">Header <code>&lt;cmath&gt;</code> changes</h3>
 
 <p>
 Some C libraries declare obsolete <code>int isinf(double)</code> or
@@ -191,7 +191,7 @@ will use them and import them into names
 instead of defining the correct signatures.
 </p>
 
-<h3>Header <code>&lt;math.h&gt;</code> changes</h3>
+<h3 id="math.h">Header <code>&lt;math.h&gt;</code> changes</h3>
 
 <p>
 The C++ library now provides its own <code>&lt;math.h&gt;</code> header that
@@ -202,7 +202,7 @@ Code which assumes that <code>sin</code>
 <code>isfinite</code> etc. are macros may no longer compile.
 </p>
 
-<h3>Header <code>&lt;stdlib.h&gt;</code> changes</h3>
+<h3 id="stdlib.h">Header <code>&lt;stdlib.h&gt;</code> changes</h3>
 
 <p>
 The C++ library now provides its own <code>&lt;stdlib.h&gt;</code> header that
@@ -220,7 +220,7 @@ responsible for ensuring their headers w
 the C++ standard library.
 </p>
 
-<h4>Call of overloaded '<code>abs(unsigned int&amp;)</code>' is ambiguous</h4>
+<h4 id="overloaded-abs">Call of overloaded '<code>abs(unsigned int&amp;)</code>' is ambiguous</h4>
 
 <p>
 The additional overloads can cause the compiler to reject invalid code that
@@ -241,7 +241,7 @@ Since calling <code>abs()</code> on an u
 this code will become explicitly invalid as per discussion in the LWG.
 </p>
 
-<h3>Optimizations remove null pointer checks for <code>this</code></h3>
+<h3 id="this-cannot-be-null">Optimizations remove null pointer checks for <code>this</code></h3>
 
 <p>
 When optimizing, GCC now assumes the <code>this</code> pointer can never be
@@ -260,7 +260,7 @@ this optimization. That option also disa
 pointers, not only those involving <code>this</code>.
 </p>
 
-<h3>Deprecation of <code>std::auto_ptr</code></h3>
+<h3 id="deprecation-of-auto_ptr">Deprecation of <code>std::auto_ptr</code></h3>
 
 <p>
 The <code>std::auto_ptr</code> class template was deprecated in C++11, so GCC
@@ -269,7 +269,7 @@ now warns about its usage.  This warning
 to port the code to use C++11's <code>std::unique_ptr</code> instead.
 </p>
 
-<h3>'constexpr' needed for in-class initialization of static data member</h3>
+<h3 id="constexpr-needed">'constexpr' needed for in-class initialization of static data member</h3>
 
 <p>
 Since C++11, the <code>constexpr</code> keyword is needed when initializing a
@@ -290,7 +290,7 @@ C++11 or later.  Programs relying on the
 error.  The fix is to use <code>constexpr</code> instead of <code>const</code>.
 </p>
 
-<h3>Stricter flexible array member rules</h3>
+<h3 id="flexible-array-members">Stricter flexible array member rules</h3>
 
 <p>
 As of this release, the C++ compiler is now more strict about flexible array
@@ -324,7 +324,7 @@ to <tt>T[0]</tt>).  This is a silent ABI
 <tt>-fabi-version</tt> or <tt>-Wabi</tt> option to disable or warn about.
 </p>
 
-<h3>More aggressive optimization of <code>-flifetime-dse</code></h3>
+<h3 id="flifetime-dse">More aggressive optimization of <code>-flifetime-dse</code></h3>
 
 <p>
 The C++ compiler (with enabled <code>-flifetime-dse</code>)
@@ -373,7 +373,7 @@ the option <code>-flifetime-dse=1</code>
 this optimization.
 </p>
 
-<h2>-Wmisleading-indentation</h2>
+<h2 id="Wmisleading-indentation">-Wmisleading-indentation</h2>
 <p>
 A new warning <code>-Wmisleading-indentation</code> was added
 to <code>-Wall</code>, warning about places where the indentation of
@@ -437,7 +437,7 @@ but given that the code was confusing wh
 the indentation of the source was fixed instead.
 </p>
 
-<h2>-Wnonnull-compare</h2>
+<h2 id="Wnonnull-compare">-Wnonnull-compare</h2>
 <p>
 A new warning <code>-Wnonnull-compare</code> was added to <code>-Wall</code>.
 It warns about comparing parameters declared as <code>nonnull</code> with
@@ -455,14 +455,14 @@ foo (void *p)
 }
 </code></pre>
 
-<h2>Plugin issues</h2>
+<h2 id="plugins">Plugin issues</h2>
 
 <p>
 The internals of GCC have seen various improvements, and these may affect
 plugins.  Some notes on porting GCC plugins to GCC 6 follow.
 </p>
 
-<h3><code>gimple</code> became a struct, rather than a pointer</h3>
+<h3 id="gimple-api"><code>gimple</code> became a struct, rather than a pointer</h3>
 
 <p>
 Prior to GCC 6, <code>gimple</code> meant a <b>pointer</b> to a statement.
@@ -512,7 +512,7 @@ typedef gimple gimple_stmt_ptr;
 #end
 </code></pre>
 
-<h2>Links</h2>
+<h2 id="links">Links</h2>
 
 <p>
 Marek Polacek <a href="https://lists.fedoraproject.org/archives/list/devel@lists.fedoraproject.org/message/DH7M2ADHM6XCRFTRRSKZD6MWFUJKHBZK/";>Fedora mass rebuild 2016 on x86_64</a>