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<base href="https://bugs.llvm.org/">
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<body><table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - crash with -fsemantic-interposition: "Alias cannot point to an interposable alias""
href="https://bugs.llvm.org/show_bug.cgi?id=50466">50466</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>crash with -fsemantic-interposition: "Alias cannot point to an interposable alias"
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>All
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>enhancement
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>-New Bugs
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>szabolcs.nagy@arm.com
</td>
</tr>
<tr>
<th>CC</th>
<td>htmldeveloper@gmail.com, llvm-bugs@lists.llvm.org, neeilans@live.com, richard-llvm@metafoo.co.uk
</td>
</tr></table>
<p>
<div>
<pre>the following code uses various gnu extensions and compiles with gcc:
void b();
#pragma redefine_extname b b_ext
void b() {}
__typeof(b) c __asm__("c_asm") __attribute__((alias("b_ext")));
__typeof(b) a __attribute__((alias("c_asm")));
void try_a() { a(); }
void try_b() { b(); }
void try_c() { c(); }
with clang -fPIC -fsemantic-interposition, using a clang built with assertions,
i see
Alias cannot point to an interposable alias
void (...)* @a
fatal error: error in backend: Broken module found, compilation aborted!
PLEASE submit a bug report to <a href="https://bugs.llvm.org/">https://bugs.llvm.org/</a> and include the crash
backtrace, preprocessed source, and associated run script.
Stack dump:
0. Program arguments:
/opt/compiler-explorer/clang-assertions-trunk/bin/clang++ -g -o /app/output.s
-mllvm --x86-asm-syntax=intel -S
--gcc-toolchain=/opt/compiler-explorer/gcc-snapshot -fcolor-diagnostics
-fno-crash-diagnostics -xc -fPIC -fsemantic-interposition <source>
1. <eof> parser at end of file
2. Code generation
#0 0x000055a9640fa62c llvm::sys::PrintStackTrace(llvm::raw_ostream&, int)
(/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x375562c)
#1 0x000055a9640f84e4 llvm::sys::RunSignalHandlers()
(/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x37534e4)
#2 0x000055a9640f8765 llvm::sys::CleanupOnSignal(unsigned long)
(/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3753765)
#3 0x000055a9640531df llvm::CrashRecoveryContext::HandleExit(int)
(/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x36ae1df)
#4 0x000055a9640f23ee llvm::sys::Process::Exit(int, bool)
(/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x374d3ee)
#5 0x000055a961d5168e LLVMErrorHandler(void*, std::__cxx11::basic_string<char,
std::char_traits<char>, std::allocator<char> > const&, bool) cc1_main.cpp:0:0
#6 0x000055a96405a859 llvm::report_fatal_error(llvm::Twine const&, bool)
(/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x36b5859)
#7 0x000055a96405a9a8
(/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x36b59a8)
#8 0x000055a963975f15
(/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x2fd0f15)
#9 0x000055a9638e7197 llvm::FPPassManager::doFinalization(llvm::Module&)
(/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x2f42197)
#10 0x000055a9638f153b llvm::legacy::PassManagerImpl::run(llvm::Module&)
(/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x2f4c53b)
#11 0x000055a9643d09a5 (anonymous
namespace)::EmitAssemblyHelper::EmitAssemblyWithNewPassManager(clang::BackendAction,
std::unique_ptr<llvm::raw_pwrite_stream,
std::default_delete<llvm::raw_pwrite_stream> >) BackendUtil.cpp:0:0
#12 0x000055a9643d41f3 clang::EmitBackendOutput(clang::DiagnosticsEngine&,
clang::HeaderSearchOptions const&, clang::CodeGenOptions const&,
clang::TargetOptions const&, clang::LangOptions const&, llvm::StringRef,
llvm::Module*, clang::BackendAction, std::unique_ptr<llvm::raw_pwrite_stream,
std::default_delete<llvm::raw_pwrite_stream> >)
(/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3a2f1f3)
#13 0x000055a96506b7aa
clang::BackendConsumer::HandleTranslationUnit(clang::ASTContext&)
(/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x46c67aa)
#14 0x000055a965ece4f9 clang::ParseAST(clang::Sema&, bool, bool)
(/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x55294f9)
#15 0x000055a96506b948 clang::CodeGenAction::ExecuteAction()
(/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x46c6948)
#16 0x000055a9649ea951 clang::FrontendAction::Execute()
(/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4045951)
#17 0x000055a964986522
clang::CompilerInstance::ExecuteAction(clang::FrontendAction&)
(/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3fe1522)
#18 0x000055a964ab5f2a
clang::ExecuteCompilerInvocation(clang::CompilerInstance*)
(/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4110f2a)
#19 0x000055a961d5358c cc1_main(llvm::ArrayRef<char const*>, char const*,
void*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x13ae58c)
#20 0x000055a961d4e929 ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&)
driver.cpp:0:0
#21 0x000055a96483d815 void llvm::function_ref<void
()>::callback_fn<clang::driver::CC1Command::Execute(llvm::ArrayRef<llvm::Optional<llvm::StringRef>
<span class="quote">>, std::__cxx11::basic_string<char, std::char_traits<char>,</span >
std::allocator<char> >*, bool*) const::'lambda'()>(long) Job.cpp:0:0
#22 0x000055a964053023
llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>)
(/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x36ae023)
#23 0x000055a96483e1b4
clang::driver::CC1Command::Execute(llvm::ArrayRef<llvm::Optional<llvm::StringRef>
<span class="quote">>, std::__cxx11::basic_string<char, std::char_traits<char>,</span >
std::allocator<char> >*, bool*) const (.part.161) Job.cpp:0:0
#24 0x000055a9648162ca
clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&,
clang::driver::Command const*&) const
(/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3e712ca)
#25 0x000055a964816f6f
clang::driver::Compilation::ExecuteJobs(clang::driver::JobList const&,
llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*> >&) const
(/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3e71f6f)
#26 0x000055a96482077a
clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&,
llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*> >&)
(/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3e7b77a)
#27 0x000055a961c7c698 main
(/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x12d7698)
#28 0x00007f61094980b3 __libc_start_main
(/lib/x86_64-linux-gnu/libc.so.6+0x270b3)
#29 0x000055a961d4e49a _start
(/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x13a949a)
clang-13: error: clang frontend command failed with exit code 70 (use -v to see
invocation)
Compiler returned: 70</pre>
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