On Sat, Nov 05, 2016 at 10:50:57PM +0100, Mark Wielaard wrote:
> The attached patch adds an explanation of the new
> -Wshadow=(global|local|compatible-local) to gcc-7/changes.html.
>
> OK to commit?
Ping?
> Index: htdocs/gcc-7/changes.html
> ===================================================================
> RCS file: /cvs/gcc/wwwdocs/htdocs/gcc-7/changes.html,v
> retrieving revision 1.21
> diff -u -r1.21 changes.html
> --- htdocs/gcc-7/changes.html 26 Oct 2016 19:08:10 -0000 1.21
> +++ htdocs/gcc-7/changes.html 5 Nov 2016 20:41:35 -0000
> @@ -119,6 +119,60 @@
> <span class="boldmagenta">~^</span>
> <span class="boldmagenta">~~~~~</span>
> <span class="green">%d</span>
> </pre></blockquote></li>
> +
> +<li>The <code>-Wshadow</code> warning has been split into 3
> +variants. <code>-Wshadow=global</code> warns for any shadowing. This
> +is the default when using <code>-Wshadow</code> without any
> +argument. <code>-Wshadow=local</code> only warns for a local variable
> +shadowing another local variable or
> +parameter. <code>-Wshadow=compatible-local</code> only warns for a
> +local variable shadowing another local variable or parameter whose
> +type is compatible (in C++ compatible means that the type of the
> +shadowing variable can be converted to that of the shadowed variable).
> +
> +The following example shows the different kinds of shadow
> +warnings:<blockquote><pre>
> +enum operation { add, count };
> +struct container { int nr; };
> +
> +int
> +container_count (struct container c, int count)
> +{
> + int r = 0;
> + for (int count = 0; count > 0; count--)
> + {
> + struct container count = c;
> + r += count.nr;
> + }
> + return r;
> +}</pre></blockquote>
> +
> +<code>-Wshadow=compatible-local</code> will warn for the parameter being
> +shadowed with the same type:<blockquote><pre>
> +<b>warn-test.c:8:12:</b> <span class="boldmagenta">warning:</span>
> declaration of '<b>count</b>' shadows a parameter [<span
> class="boldmagenta">-Wshadow=compatible-local</span>]
> + for (int <span class="boldmagenta">count</span> = 0; count > 0; count--)
> + <span class="boldmagenta">^~~~~</span>
> +<b>warn-test.c:5:42:</b> <span class="boldcyan">note:</span> shadowed
> declaration is here
> + container_count (struct container c, int <span
> class="boldcyan">count</span>)
> + <span
> class="boldcyan">^~~~~</span></pre></blockquote>
> +
> +<code>-Wshadow=local</code> will warn for the above and for the shadowed
> +declaration with incompatible type:<blockquote><pre>
> +<b>warn-test.c:10:24:</b> <span class="boldmagenta">warning:</span>
> declaration of '<b>count</b>' shadows a previous local [<span
> class="boldmagenta">-Wshadow=local</span>]
> + struct container <span class="boldmagenta">count</span> = c;
> + <span class="boldmagenta">^~~~~</span>
> +<b>warn-test.c:8:12:</b> <span class="boldcyan">note:</span> shadowed
> declaration is here
> + for (int <span class="boldcyan">count</span> = 0; count > 0; count--)
> + <span class="boldcyan">^~~~~</span></pre></blockquote>
> +
> +<code>-Wshadow=global</code> will warn for all of the above and the shadowing
> +of the global declaration: <blockquote><pre>
> +<b>warn-test.c:5:42:</b> <span class="boldmagenta">warning:</span>
> declaration of '<b>count</b>' shadows a global declaration [<span
> class="boldmagenta">-Wshadow</span>]
> + container_count (struct container c, int <span
> class="boldmagenta">count</span>)
> + <span
> class="boldmagenta">^~~~~</span>
> +<b>warn-test.c:1:23:</b> <span class="boldcyan">note:</span> shadowed
> declaration is here
> + enum operation { add, <span class="boldcyan">count</span> };
> + <span
> class="boldcyan">^~~~~</span></pre></blockquote></li>
> </ul>
>
> <h3 id="c">C</h3>
