Apple LLDB 900.0.64 crash

Hi :slight_smile:

I hope this is an appropriate use of this mailing list, my apologies if not. I couldn’t find any form to report LLDB bugs and wasn’t sure where to ask.

With a recent update of Xcode I started getting an LLDB crash frequently while attempting to debug. (Not sure exactly which Xcode release sadly.) Sometimes it occurs when the debugger pauses execution (e.g. due to an assertion failure), other times when I attempt to inspect certain variables.

Here’s the call stack of the offending thread:

Thread 7 Crashed:: RPC packet thread for client tid 00007997 (31127)
0 0x0000000108f98157 clang::ClassTemplateSpecializationDecl::Create(clang::ASTContext&, clang::TagTypeKind, clang::DeclContext*, clang::SourceLocation, clang::SourceLocation, clang::ClassTemplateDecl*, llvm::ArrayRefclang::TemplateArgument, clang::ClassTemplateSpecializationDecl*) + 71
1 0x000000010a6fc39c lldb_private::ClangASTContext::CreateClassTemplateSpecializationDecl(clang::DeclContext*, clang::ClassTemplateDecl*, int, lldb_private::ClangASTContext::TemplateParameterInfos const&) + 308
2 0x000000010a546de4 DWARFASTParserClang::ParseTypeFromDWARF(lldb_private::SymbolContext const&, DWARFDIE const&, lldb_private::Log*, bool*) + 5890
3 0x000000010a6e2623 SymbolFileDWARF::ParseType(lldb_private::SymbolContext const&, DWARFDIE const&, bool*) + 171
4 0x000000010a6dc33f SymbolFileDWARF::GetTypeForDIE(DWARFDIE const&, bool) + 369
5 0x000000010a6dbc6e SymbolFileDWARF::ResolveType(DWARFDIE const&, bool, bool) + 68
6 0x000000010a6dbbed SymbolFileDWARF::ResolveTypeUID(unsigned long long) + 45
7 0x000000010a759942 lldb_private::Type::ResolveClangType(lldb_private::Type::ResolveStateTag) + 154
8 0x000000010a759604 lldb_private::Type::GetForwardCompilerType() + 26
9 0x000000010a59be5f lldb_private::ValueObjectVariable::GetCompilerTypeImpl() + 37
10 0x000000010a58cf67 lldb_private::ValueObject::MaybeCalculateCompleteType() + 39
11 0x000000010a5912dd lldb_private::ValueObject::GetObjectRuntimeLanguage() + 33
12 0x000000010a59167b lldb_private::ValueObject::IsRuntimeSupportValue() + 73
13 0x0000000107c5faec lldb::SBFrame::GetVariables(lldb::SBVariablesOptions const&) + 624
14 0x0000000107c5fda4 lldb::SBFrame::GetVariables(bool, bool, bool, bool, lldb::DynamicValueType) + 208
15 lldb-rpc-server 0x0000000106220aef rpc_server::_ZN4lldb7SBFrame12GetVariablesEbbbbNS_16DynamicValueTypeE::HandleRPCCall(rpc_common::Connection&, rpc_common::RPCStream&, rpc_common::RPCStream&) + 219
16 lldb-rpc-server 0x00000001061e662a rpc_common::Connection::PrivateHandleRPCPacket(rpc_common::RPCPacket&, rpc_common::RPCPacket&, bool&) + 506
17 lldb-rpc-server 0x00000001061e730c rpc_common::Connection::HandleRPCPacket(rpc_common::RPCPacket&) + 62
18 lldb-rpc-server 0x00000001061ea862 Packets::ProcessPackets() + 254
19 lldb-rpc-server 0x00000001061ea68b Packets::ReadThread() + 187
20 lldb-rpc-server 0x00000001061ea5cb Packets::RunReadThread(void*) + 9
21 libsystem_pthread.dylib 0x00007fff7b8906c1 _pthread_body + 340
22 libsystem_pthread.dylib 0x00007fff7b89056d _pthread_start + 377
23 libsystem_pthread.dylib 0x00007fff7b88fc5d thread_start + 13

The full LLDB crash dump can be downloaded here:

The (Apple) LLDB version is lldb-900.0.64. Not sure whether/how this corresponds to “official” LLDB version numbers.

Unfortunately I’m unable to share the code for confidentiality reasons. I’ll attempt to isolate the issue but I thought I’d ask here in case it’s a known issue or the cause is obvious.


Johan Øverbye
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Hi Johan,

If it is Apple specific, create a report on the Apple Bug Reporter, at

If you can reproduce the error with stock lldb, please report it on the LLVM bugtracker, at


This is a crash that is happening as we are trying to translate DWARF back into Clang ASTs. You can enable DWARF logging by doing:

(lldb) log enable -f /tmp/dwarf.log dwarf info

Or add that line to your ~/.lldbinit file.

Then make it crash and we will have a log of what was wrong and might have an idea of the type that is causing the problem. If you get this log, there should be a line from this code:

log, "SymbolFileDWARF::ParseType (die = 0x%8.8x, decl_ctx = %p (die "
“0x%8.8x)) %s name = ‘%s’)”,
die.GetOffset(), static_cast<void *>(context),
context_die.GetOffset(), die.GetTagAsCString(), die.GetName());

right before it crashed. It might help to reproduce a minimal example that can be used to fix this issue.

Remember to remove the “log enable” from your ~/.lldbinit file if you did add it, otherwise you will slow down debugging in future sessions.

Greg Clayton