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<base href="https://bugs.llvm.org/">
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<body><table border="1" cellspacing="0" cellpadding="8">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - NULL pointer dereference in FillInEmptyInitForField"
href="https://bugs.llvm.org/show_bug.cgi?id=50538">50538</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>NULL pointer dereference in FillInEmptyInitForField
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
<tr>
<th>Version</th>
<td>12.0
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>Frontend
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>radwanski.michal@outlook.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org, neeilans@live.com, richard-llvm@metafoo.co.uk
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=24901" name="attach_24901" title="Stack trace">attachment 24901</a> <a href="attachment.cgi?id=24901&action=edit" title="Stack trace">[details]</a></span>
Stack trace
Clang crashes when compiling. According to godbolt.org, this affects all
versions since 6.0.0. Tested on Fedora 34, with clang 12 from repositories.
POC:
template<typename Ti>
struct Wrap { Ti _; };
template<typename Ti, typename = decltype(Wrap<Ti> {0})>
using Void = void;
template<typename, typename = void>
struct variant;
template<typename Ti>
struct variant< Ti, Void<Ti> >;
struct S { int x; variant<S>& v; };
variant<S> v;
This code was hand-minimized from this one (using libstdc++):
#include <variant>
struct S;
using V = std::variant<int, S>;
struct S { int x; V& v; };
V l = 0;
After a bit of investigation, I come to conclusion, that there is a null
pointer dereference in FillInEmptyInitForField:
InitListExpr *ILE
/* some code */
<< ILE->getSyntacticForm()->getSourceRange();
Here, ILE->getSyntacticForm() evaluates to nullptr. I don't know enough
internals to know how to fix it.
I'm attaching the full stack trace I get. Top entries (excluding those from the
signal handler) are inline here:
#4 0x00007f7e9edb80d6 clang::Stmt::getSourceRange() const
/usr/src/debug/clang-12.0.0-0.3.rc1.fc34.x86_64/x86_64-redhat-linux-gnu/../lib/AST/Stmt.cpp:325:3
#5 0x00007f7e9f436737 clang::Sema::SemaDiagnosticBuilder const&
clang::Sema::SemaDiagnosticBuilder::operator<<<clang::SourceRange,
void>(clang::SourceRange&&) const
/usr/src/debug/clang-12.0.0-0.3.rc1.fc34.x86_64/x86_64-redhat-linux-gnu/../include/clang/Sema/Sema.h:1683:7
#6 0x00007f7e9f436737 FillInEmptyInitForField
/usr/src/debug/clang-12.0.0-0.3.rc1.fc34.x86_64/x86_64-redhat-linux-gnu/../lib/Sema/SemaInit.cpp:697:54
#7 0x00007f7e9f436d16 FillInEmptyInitializations
/usr/src/debug/clang-12.0.0-0.3.rc1.fc34.x86_64/x86_64-redhat-linux-gnu/../lib/Sema/SemaInit.cpp:820:9
#8 0x00007f7e9f4364b6 FillInEmptyInitForField
/usr/src/debug/clang-12.0.0-0.3.rc1.fc34.x86_64/x86_64-redhat-linux-gnu/../lib/Sema/SemaInit.cpp:729:31
#9 0x00007f7e9f436d16 FillInEmptyInitializations
/usr/src/debug/clang-12.0.0-0.3.rc1.fc34.x86_64/x86_64-redhat-linux-gnu/../lib/Sema/SemaInit.cpp:820:9
#10 0x00007f7e9f439c5d InitListChecker
/usr/src/debug/clang-12.0.0-0.3.rc1.fc34.x86_64/x86_64-redhat-linux-gnu/../lib/Sema/SemaInit.cpp:965:5
#11 0x00007f7e9f439f17 diagnoseListInit
/usr/src/debug/clang-12.0.0-0.3.rc1.fc34.x86_64/x86_64-redhat-linux-gnu/../lib/Sema/SemaInit.cpp:8912:3
#12 0x00007f7e9f43aad7 clang::InitializationSequence::Diagnose(clang::Sema&,
clang::InitializedEntity const&, clang::InitializationKind const&,
llvm::ArrayRef<clang::Expr*>)
/usr/src/debug/clang-12.0.0-0.3.rc1.fc34.x86_64/x86_64-redhat-linux-gnu/../lib/Sema/SemaInit.cpp:9361:5</pre>
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