[llvm-bugs] [Bug 50054] New: getASTRecordLayout called before that type's base classes are saved

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=50054

            Bug ID: 50054
           Summary: getASTRecordLayout called before that type's base
                    classes are saved
           Product: lldb
           Version: unspecified
          Hardware: PC
                OS: Windows NT
            Status: NEW
          Severity: normal
          Priority: P
         Component: All Bugs
          Assignee: lldb-dev at lists.llvm.org
          Reporter: emrekultursay at google.com
                CC: jdevlieghere at apple.com, llvm-bugs at lists.llvm.org

Created attachment 24776
  --> https://bugs.llvm.org/attachment.cgi?id=24776&action=edit
Full stack trace

This is a case where LLDB calls `Context.getASTRecordLayout(...)` for a class
BEFORE the `CXXRecordDecl::setBases()` for that same class.

As a result, `getASTRecordLayout()` computes and caches an layout without any
base classes, and subsequent calls use that cached, incorrect result. 

This causes a segfault in LLDB due to downstream accesses using FieldNo values
that do not exist in ASTRecordLayout.

I can only reproduce this by attaching to a binary that a customer provided,
and I cannot share that publicly here. However, I hope maybe some LLDB experts
here might be able to guide/help by looking at the stack trace here.

* Topmost frame: Computes and saves the ASTRecordLayout for the problematic
class without any base class information.
* Frame with asterisk(*): Has not processed/saved the base classes for that
same class yet.


>	clang::ASTContext::getASTRecordLayout Line 3339	
        `anonymous namespace'::EmptySubobjectMap::ComputeEmptySubobjectSizes
Line 203   
        `anonymous namespace'::EmptySubobjectMap::EmptySubobjectMap Line 179    
        clang::ASTContext::getASTRecordLayout Line 3377 
        `anonymous namespace'::EmptySubobjectMap::ComputeEmptySubobjectSizes
Line 203   
        `anonymous namespace'::EmptySubobjectMap::EmptySubobjectMap Line 179    
        clang::ASTContext::getASTRecordLayout Line 3377 
        `anonymous namespace'::EmptySubobjectMap::ComputeEmptySubobjectSizes
Line 203   
        `anonymous namespace'::EmptySubobjectMap::EmptySubobjectMap Line 179    
        clang::ASTContext::getASTRecordLayout Line 3377 
        `anonymous namespace'::EmptySubobjectMap::ComputeEmptySubobjectSizes
Line 203   
        `anonymous namespace'::EmptySubobjectMap::EmptySubobjectMap Line 179    
        clang::ASTContext::getASTRecordLayout Line 3377 
        `anonymous namespace'::EmptySubobjectMap::ComputeEmptySubobjectSizes
Line 203   
        `anonymous namespace'::EmptySubobjectMap::EmptySubobjectMap Line 179    
        clang::ASTContext::getASTRecordLayout Line 3377 
        `anonymous namespace'::EmptySubobjectMap::ComputeEmptySubobjectSizes
Line 203   
        `anonymous namespace'::EmptySubobjectMap::EmptySubobjectMap Line 179    
        clang::ASTContext::getASTRecordLayout Line 3377 
        clang::ASTContext::getTypeInfoImpl Line 2258    
        clang::ASTContext::getTypeInfo Line 1879        
        clang::ASTContext::getTypeInfo Line 2116        
        clang::ASTContext::getTypeSize Line 2122        
        lldb_private::TypeSystemClang::GetBitSize Line 4588     
        lldb_private::CompilerType::GetBitSize Line 484 
        lldb_private::CompilerType::GetByteSize Line 490        
        DWARFASTParserClang::ParseSingleMember Line 2680        
        DWARFASTParserClang::ParseChildMembers Line 2801        
        DWARFASTParserClang::CompleteRecordType Line 2002       
        DWARFASTParserClang::CompleteTypeFromDWARF Line 2126    
        ...
        DWARFASTParserClang::ParseChildMembers Line 2888        
        DWARFASTParserClang::CompleteRecordType Line 2002       
        DWARFASTParserClang::CompleteTypeFromDWARF Line 2126    
        ...
        DWARFASTParserClang::ParsePointerToMemberType Line 1362 
        DWARFASTParserClang::ParseTypeFromDWARF Line 530        
        ...
        DWARFASTParserClang::ParseChildParameters Line 3014     
        DWARFASTParserClang::ParseSubroutine Line 942   
        DWARFASTParserClang::ParseTypeFromDWARF Line 522        
        ...
        DWARFASTParserClang::CompleteRecordType Line 2003       
        DWARFASTParserClang::CompleteTypeFromDWARF Line 2126    
        ...
        DWARFASTParserClang::ParseSingleMember Line 2562        
        DWARFASTParserClang::ParseChildMembers Line 2801        
        DWARFASTParserClang::CompleteRecordType Line 2002       
        DWARFASTParserClang::CompleteTypeFromDWARF Line 2126    
        ...
        DWARFASTParserClang::ParsePointerToMemberType Line 1362 
        DWARFASTParserClang::ParseTypeFromDWARF Line 530        
        ...
        DWARFASTParserClang::ParseChildParameters Line 3014     
        DWARFASTParserClang::ParseSubroutine Line 942   
        DWARFASTParserClang::ParseTypeFromDWARF Line 522        
        ...
        DWARFASTParserClang::CompleteRecordType Line 2003       
        DWARFASTParserClang::CompleteTypeFromDWARF Line 2126    
        ...
        DWARFASTParserClang::ParseSingleMember Line 2562        
        DWARFASTParserClang::ParseChildMembers Line 2801        
        DWARFASTParserClang::CompleteRecordType Line 2002       
        DWARFASTParserClang::CompleteTypeFromDWARF Line 2126    
        ...
        DWARFASTParserClang::ParsePointerToMemberType Line 1362 
        DWARFASTParserClang::ParseTypeFromDWARF Line 530        
        ...
        DWARFASTParserClang::ParseChildParameters Line 3014     
        DWARFASTParserClang::ParseSubroutine Line 942   
        DWARFASTParserClang::ParseTypeFromDWARF Line 522        
        ...
        DWARFASTParserClang::CompleteRecordType Line 2003       
        DWARFASTParserClang::CompleteTypeFromDWARF Line 2126    
        ...
        DWARFASTParserClang::ParseSingleMember Line 2562        
        DWARFASTParserClang::ParseChildMembers Line 2801        
        DWARFASTParserClang::CompleteRecordType Line 2002       
        DWARFASTParserClang::CompleteTypeFromDWARF Line 2126    
        ...
        DWARFASTParserClang::ParsePointerToMemberType Line 1362 
        DWARFASTParserClang::ParseTypeFromDWARF Line 530        
        ...
        DWARFASTParserClang::ParseChildParameters Line 3014     
        DWARFASTParserClang::ParseSubroutine Line 942   
        DWARFASTParserClang::ParseTypeFromDWARF Line 522        
        ...
        DWARFASTParserClang::CompleteRecordType Line 2003       
        DWARFASTParserClang::CompleteTypeFromDWARF Line 2126    
        ...
        DWARFASTParserClang::ParseSingleMember Line 2562        
        DWARFASTParserClang::ParseChildMembers Line 2801        
        DWARFASTParserClang::CompleteRecordType Line 2002       
        DWARFASTParserClang::CompleteTypeFromDWARF Line 2126    
        ...
        DWARFASTParserClang::ParseChildMembers Line 2888        
        DWARFASTParserClang::CompleteRecordType Line 2002       
        DWARFASTParserClang::CompleteTypeFromDWARF Line 2126    
        ...
        DWARFASTParserClang::ParseChildMembers Line 2888        
*       DWARFASTParserClang::CompleteRecordType Line 2002       
        DWARFASTParserClang::CompleteTypeFromDWARF Line 2126    
        ...
        DWARFASTParserClang::ParseSingleMember Line 2562        
        DWARFASTParserClang::ParseChildMembers Line 2801        
        DWARFASTParserClang::CompleteRecordType Line 2002       
        DWARFASTParserClang::CompleteTypeFromDWARF Line 2126    
        ...
        DWARFASTParserClang::ParsePointerToMemberType Line 1362 
        DWARFASTParserClang::ParseTypeFromDWARF Line 530        
        ...
        DWARFASTParserClang::ParseChildParameters Line 3014     
        DWARFASTParserClang::ParseSubroutine Line 942   
        DWARFASTParserClang::ParseTypeFromDWARF L
        ...
        DWARFASTParserClang::CompleteRecordType Line 2003       
        DWARFASTParserClang::CompleteTypeFromDWARF Line 2126    
        ...
        DWARFASTParserClang::ParseChildMembers Line 2888        
        DWARFASTParserClang::CompleteRecordType Line 2002       
        DWARFASTParserClang::CompleteTypeFromDWARF Line 2126    
        SymbolFileDWARF::CompleteType Line 1484 
        lldb_private::TypeSystemClang::CompleteTagDecl Line 9100        
        GetCompleteQualType Line 2607   
        lldb_private::TypeSystemClang::GetNumChildren Line 5166 
        lldb_private::TypeSystemClang::GetNumChildren Line 5281 
        lldb_private::ValueObjectDynamicValue::CalculateNumChildren Line 96     
        lldb_private::ValueObject::GetNumChildren Line 561      
        lldb::SBValue::GetNumChildren Line 993  
        lldb::SBValue::GetNumChildren Line 982  
        [External Code] 


Full stack trace is attached.

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