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| <title>Compilers corner</title><link rel="stylesheet" href="boostbook.css" type="text/css"><meta name="generator" content="DocBook XSL-NS Stylesheets V1.75.2"><link rel="home" href="index.html" title="Meta State Machine (MSM) V2.12"><link rel="up" href="ch04.html" title="Chapter 4. Performance / Compilers"><link rel="prev" href="ch04s04.html" title="Limitations"><link rel="next" href="ch05.html" title="Chapter 5. Questions & Answers"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center"> Compilers corner </th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ch04s04.html">Prev</a> </td><th width="60%" align="center">Chapter 4. Performance / Compilers</th><td width="20%" align="right"> <a accesskey="n" href="ch05.html">Next</a></td></tr></table><hr></div><div class="sect1" title="Compilers corner"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="d0e2537"></a> Compilers corner </h2></div></div></div><p>Compilers are sometimes full of surprises and such strange errors happened in |
| the course of the development that I wanted to list the most fun for readers’ |
| entertainment.</p><p><span class="underline">VC8</span>: </p><pre class="programlisting">template <class StateType> |
| typename ::boost::enable_if< |
| typename ::boost::mpl::and_< |
| typename ::boost::mpl::not_< |
| typename has_exit_pseudo_states<StateType>::type |
| >::type, |
| typename ::boost::mpl::not_< |
| typename is_pseudo_exit<StateType>::type |
| >::type |
| >::type, |
| BaseState*>::type </pre><p>I get the following error:</p><p>error C2770: invalid explicit template argument(s) for '`global |
| namespace'::boost::enable_if<...>::...' </p><p>If I now remove the first “::” in ::boost::mpl , the compiler shuts up. So in |
| this case, it is not possible to follow Boost’s guidelines.</p><p><span class="underline">VC9</span>:</p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>This one is my all times’ favorite. Do you know why the exit |
| pseudo states are referenced in the transition table with a |
| “submachine::exit_pt” ? Because “exit” will crash the compiler. |
| “Exit” is not possible either because it will crash the compiler on |
| one machine, but not on another (the compiler was installed from the |
| same disk).</p></li><li class="listitem"><p>Sometimes, removing a policy crashes the compiler, so some |
| versions are defining a dummy policy called WorkaroundVC9.</p></li><li class="listitem"><p>Typeof: While g++ and VC9 compile “standard” state machines in |
| comparable times, Typeof (while in both ways natively supported) |
| seems to behave in a quadratic complexity with VC9 and VC10.</p></li><li class="listitem"><p>eUML: in case of a compiler crash, changing the order of state |
| definitions (first states without entry or exit) sometimes solves |
| the problem.</p></li></ul></div><p><span class="underline">g++ 4.x</span>: Boring compiler, almost all is |
| working almost as expected. Being not a language lawyer I am unsure about the |
| following “Typeof problem”. VC9 and g++ disagree on the question if you can |
| derive from the BOOST_TYPEOF generated type without first defining a typedef. I |
| will be thankful for an answer on this. I only found two ways to break the compiler:</p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Add more eUML constructs until something explodes (especially with |
| g++-4.4) </p></li><li class="listitem"><p>The build_terminate function uses 2 mpl::push_back instead of |
| mpl::insert_range because g++ would not accept insert_range.</p></li></ul></div><p>You can test your compiler’s decltype implementation with the <a class="link" href="examples/CompilerStressTestEuml.cpp" target="_top">following stress |
| test</a> and reactivate the commented-out code until the compiler |
| crashes.</p></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="ch04s04.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="ch04.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="ch05.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top"> Limitations </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> Chapter 5. Questions & Answers</td></tr></table></div></body></html> |
