On Wed, 11 Feb 2015, Marek Polacek wrote: > Oops, I must have been thinking of __STDC_VERSION__ when writing that. > Fixed, thanks.
Here is a small set of tweaks on top of this (no material changes). Applied. Gerald Index: porting_to.html =================================================================== RCS file: /cvs/gcc/wwwdocs/htdocs/gcc-5/porting_to.html,v retrieving revision 1.7 diff -u -r1.7 porting_to.html --- porting_to.html 10 Mar 2015 17:58:12 -0000 1.7 +++ porting_to.html 18 Apr 2015 19:43:37 -0000 @@ -24,6 +24,7 @@ manner. Additions and suggestions for improvement are welcome. </p> + <h2>Preprocessor issues</h2> <p>The preprocessor started to emit line markers to properly distinguish @@ -59,6 +60,7 @@ As can be seen, the <code>exitfailure</code> and <code>1</code> tokens are not on the same line anymore. + <h2>C language issues</h2> <h3>Default standard is now GNU11</h3> @@ -290,9 +292,9 @@ <p>As the default mode changed to C11, the <code>__STDC_VERSION__</code> standard macro, introduced in C95, is now defined by default, and has -the value <code>201112L</code>. +the value <code>201112L</code>.</p> -Typically, this macro is used as in the following:</p> +<p>Typically, this macro is used as in the following:</p> <pre><code> #if !defined __STDC_VERSION__ || __STDC_VERSION__ < 199901L @@ -307,12 +309,12 @@ <h4>Different meaning of the <code>%a *scanf</code> conversion specification</h4> <p>In C89, the GNU C library supports dynamic allocation via the <code>%as</code>, -<code>%aS</code>, and <code>%a[...]</code> conversion specification; see +<code>%aS</code>, and <code>%a[...]</code> conversion specifications; see <a href="https://www.gnu.org/software/libc/manual/html_node/Dynamic-String-Input.html#Dynamic-String-Input";> this</a> for more info. -But in C99, the <code>a</code> conversion specifier is a synonym for <code>f</code> -(float), so the compiler expects an argument of type <code>float *</code>. Different -meaning of <code>%a</code> is a change in semantics, and in combination with the +In C99, the <code>a</code> conversion specifier is a synonym for <code>f</code> +(float), so the compiler expects an argument of type <code>float *</code>. +This is a change in semantics, and in combination with the <code>-Wformat</code> warning option the compiler may emit additional warnings:</p> <pre><code> @@ -333,14 +335,14 @@ </pre> <p>To use the dynamic allocation conversion specifier in C99 and C11, specify -<code>m</code> as a length modifier, specified by POSIX.1-2008. That is, use +<code>m</code> as a length modifier as per POSIX.1-2008. That is, use <code>%ms</code> or <code>%m[...]</code>.</p> <h3>New warnings</h3> -<p>Several new warnings have been added to the C front end. One of the new -warnings is that GCC now warns about non-standard predefined identifiers with -the <code>-Wpedantic</code> option. For instance:</p> +<p>Several new warnings have been added to the C front end. Among others +<code>-Wpedantic</code> now warns about non-standard predefined identifiers. +For instance:</p> <pre><code> void @@ -363,14 +365,16 @@ const char *s = __extension__ __FUNCTION__; </code></pre> + <h2>C++ language issues</h2> <h3>Converting <code>std::nullptr_t</code> to <code>bool</code></h3> -<p>Converting <code>std::nullptr_t</code> to <code>bool</code> in the C++11 +<p>Converting <code>std::nullptr_t</code> to <code>bool</code> in C++11 mode now requires direct-initialization. This has been changed in -<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#1423";>DR 1423</a>. -As a consequence, the following is invalid:</p> +<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#1423";>DR 1423</a>.</p> + +<p>As a consequence, the following is invalid:</p> <pre><code> bool b = nullptr;
