Right, but the root cause of the problem is that __builtin_va_start uses a reference type in C mode. Your patch is fixing one of the places where that doesn't work. So we have a choice: either we accept the cost of making references work well enough in C to handle this weird case, or we pick a different implementation strategy for __builtin_va_start. We don't have many options, because the type of va_list is determined by the ABI and the behavior of __builtin_va_start is defined by GCC, but we may be able to (for instance) inject a "#define __builtin_va_start(list, ...) __builtin_va_start_ptr(&(list), __VA_ARGS__)" rather than using a reference type.<br>
<br><div class="gmail_quote">On Thu, Aug 8, 2013 at 12:43 AM, Artyom Skrobov <span dir="ltr"><<a href="mailto:Artyom.Skrobov@arm.com" target="_blank">Artyom.Skrobov@arm.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Richard, my patch doesn’t add support for reference types in C – it only adds the proper type-checking so that clang emits a meaningful error diagnostic in
this case, instead of crashing with a segfault.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p>
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<p class="MsoNormal"><b><span lang="EN-US" style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span lang="EN-US" style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> <a href="mailto:metafoo@gmail.com" target="_blank">metafoo@gmail.com</a> [mailto:<a href="mailto:metafoo@gmail.com" target="_blank">metafoo@gmail.com</a>]
<b>On Behalf Of </b>Richard Smith<br>
<b>Sent:</b> 08 August 2013 00:57<br>
<b>To:</b> Artyom Skrobov<br>
<b>Cc:</b> Anton Korobeynikov; <a href="mailto:cfe-commits@cs.uiuc.edu" target="_blank">cfe-commits@cs.uiuc.edu</a></span></p><div class="im"><br>
<b>Subject:</b> Re: [PATCH] in C mode, __builtin_va_start tries to accept a reference, sees a record, decides it's a C++ class, then crashes because it isn't<u></u><u></u></div><p></p>
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<p class="MsoNormal">This is truly hideous. Do we *really* want to support reference types in C, just so that we can handle __builtin_va_start?<u></u><u></u></p>
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<p class="MsoNormal">On Tue, Aug 6, 2013 at 8:26 AM, Artyom Skrobov <<a href="mailto:Artyom.Skrobov@arm.com" target="_blank">Artyom.Skrobov@arm.com</a>> wrote:<u></u><u></u></p>
<p class="MsoNormal">Anton, thank you for your suggestion.<br>
<br>
Re-submitting the patch as an attachment.<u></u><u></u></p>
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-----Original Message-----<br>
From: Anton Korobeynikov [mailto:<a href="mailto:anton@korobeynikov.info" target="_blank">anton@korobeynikov.info</a>]<br>
Sent: 05 August 2013 23:24<br>
To: Artyom Skrobov<br>
Cc: <a href="mailto:cfe-commits@cs.uiuc.edu" target="_blank">cfe-commits@cs.uiuc.edu</a><br>
Subject: Re: [PATCH] in C mode, __builtin_va_start tries to accept a reference, sees a record, decides it's a C++ class, then crashes because it isn't<br>
<br>
Please consider reading <a href="http://llvm.org/docs/DeveloperPolicy.html#making-a-patch" target="_blank">
http://llvm.org/docs/DeveloperPolicy.html#making-a-patch</a><br>
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<br>
<u></u><u></u></p>
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