From: Jakub Jelinek <jakub@redhat.com>
To: "Gerald Pfeifer" <gerald@pfeifer.com>,
"Joseph S. Myers" <joseph@codesourcery.com>,
"Jason Merrill" <jason@redhat.com>,
"Martin Liška" <mliska@suse.cz>
Cc: gcc-patches@gcc.gnu.org
Subject: [wwwdocs] Start of gcc-9/porting_to.html, some C/C++ changes.html changes
Date: Fri, 11 Jan 2019 13:35:00 -0000 [thread overview]
Message-ID: <20190111133454.GN30353@tucnak> (raw)
Hi!
The following patch
1) mentions (partial) OpenMP 5.0 support and __builtin_convertvector in
c-family section of gcc-9/changes.html
2) mentions C++2a progress in similar way how we've done it in
gcc-8/changes.html (the list doesn't include all features, feel free
to suggest what should go out of that list or be added and with what
wording, some of the cxx-status.html feature names don't look usable
in the list to me
3) lists std::is_constant_evaluated as implemented in cxx-status.html
4) adds beginning of gcc-9/porting_to.html , so far just mentions there
the lifetime of automatic compound literals
Ok for wwwdocs?
--- htdocs/gcc-9/changes.html.jj 2019-01-11 13:09:40.469122800 +0100
+++ htdocs/gcc-9/changes.html 2019-01-11 14:22:42.944333728 +0100
@@ -65,7 +65,21 @@ a work-in-progress.</p>
<!-- <h3 id="brig">BRIG (HSAIL)</h3> -->
-<!-- <h3 id="c-family">C family</h3> -->
+<h3 id="c-family">C family</h3>
+<ul>
+ <li>Version 5.0 of the <a href="https://www.openmp.org/specifications/"
+ >OpenMP specification</a> is now partially supported in the C and C++
+ compilers. For details which features of OpenMP 5.0 are and which are
+ not supported in the GCC 9 release see
+ <a href="https://gcc.gnu.org/ml/gcc-patches/2018-11/msg00628.html">this mail</a>.
+ </li>
+
+ <li>New extensions:
+ <ul>
+ <li><code>__builtin_convertvector</code> built-in for vector conversions
+ has been added. </li>
+ </ul></li>
+</ul>
<h3 id="cxx">C++</h3>
<ul>
@@ -79,6 +93,22 @@ a work-in-progress.</p>
dangling pointer, such as returning or assigning from a temporary
list. </li>
</ul></li>
+
+ <li>
+ The C++ front end has experimental support for some of the upcoming C++2a
+ draft features with the <code>-std=c++2a</code> or <code>-std=gnu++2a</code>
+ flags, including range-based for statements with initializer,
+ less eager instantiation of constexpr functions, default constructible and
+ assignable stateless lambdas, lambdas in unevaluated contexts, language
+ support for empty objects, allow pack expansion in lambda init-capture,
+ likely and unlikely attributes, class types in non-type template
+ parameters, allowing virtual function calls in constant expressions,
+ explicit(bool), signed integers are two's complement,
+ <code>std::is_constant_evaluated</code>, nested inline namespaces, etc.
+ For a full list of new features,
+ see <a href="../projects/cxx-status.html#cxx2a">the C++
+ status page</a>.
+ </li>
</ul>
<h4 id="libstdcxx">Runtime Library (libstdc++)</h4>
--- htdocs/projects/cxx-status.html.jj 2019-01-11 13:09:41.475106482 +0100
+++ htdocs/projects/cxx-status.html 2019-01-11 14:24:06.524979265 +0100
@@ -280,7 +280,7 @@
<tr>
<td> std::is_constant_evaluated </td>
<td><a href="http://wg21.link/p0595r2">P0595R2</a></td>
- <td class="unsupported"> No </td>
+ <td class="supported"> 9 </td>
<td> </td>
</tr>
<tr>
--- htdocs/gcc-9/porting_to.html.jj 2019-01-11 13:29:23.291922307 +0100
+++ htdocs/gcc-9/porting_to.html 2019-01-11 13:23:03.831090097 +0100
@@ -0,0 +1,72 @@
+<!DOCTYPE html>
+<html lang="en">
+
+<head>
+<title>Porting to GCC 9</title>
+<link rel="stylesheet" type="text/css" href="https://gcc.gnu.org/gcc.css" />
+</head>
+
+<body>
+<h1>Porting to GCC 9</h1>
+
+<p>
+The GCC 9 release series differs from previous GCC releases in
+<a href="changes.html">a number of ways</a>. Some of these are a result
+of bug fixing, and some old behaviors have been intentionally changed
+to support new standards, or relaxed in standards-conforming ways to
+facilitate compilation or run-time performance.
+</p>
+
+<p>
+Some of these changes are user visible and can cause grief when
+porting to GCC 9. This document is an effort to identify common issues
+and provide solutions. Let us know if you have suggestions for improvements!
+</p>
+
+
+<!--
+<h2 id="cpp">Preprocessor issues</h2>
+-->
+
+<h2 id="c">C language issues</h2>
+
+<h3 id="complit">Block scope compound literal's lifetime</h3>
+
+<p>
+ The C standard says that compound literals which occur inside of the body
+ of a function have automatic storage duration associated with the
+ enclosing block. Older GCC releases were putting such compound literals
+ into the scope of the whole function, so their lifetime actually ended
+ at the end of containing function. This has been fixed in GCC 9.
+ Code that relied on this extended lifetime needs to be fixed, move the
+ compound literals to whatever scope they need to accessible in.
+</p>
+ <pre><code>
+ struct S { int a, b; };
+ int foo(void) {
+ // The following line no longer compiles
+ struct S *p = &({ (struct S) { 1, 2 }; });
+ struct S *q;
+ {
+ q = &(struct S) { 3, 4 };
+ }
+ // This is invalid use after lifetime of the compound literal
+ // ended.
+ return q->b;
+ }
+ </code></pre>
+
+<!--
+<h2 id="cxx">C++ language issues</h2>
+-->
+
+<!--
+<h2 id="fortran">Fortran language issues</h2>
+-->
+
+<!--
+<h2 id="links">Links</h2>
+-->
+
+</body>
+</html>
Jakub
next reply other threads:[~2019-01-11 13:35 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-11 13:35 Jakub Jelinek [this message]
2019-01-11 18:18 ` Jeff Law
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