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[lldb][TypeSystemClang] Avoid accessing definition if none is available #9217

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merged 1 commit into from
Sep 6, 2024
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[lldb][TypeSystemClang] Avoid accessing definition if none is available #9217

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23 changes: 20 additions & 3 deletions lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,7 @@
#include "TypeSystemClang.h"

#include "clang/AST/DeclBase.h"
#include "clang/AST/DeclCXX.h"
#include "clang/AST/ExprCXX.h"
#include "llvm/ADT/STLForwardCompat.h"
#include "llvm/Support/Casting.h"
Expand Down Expand Up @@ -3650,6 +3651,15 @@ bool TypeSystemClang::IsPolymorphicClass(lldb::opaque_compiler_type_t type) {
return false;
}

/// Returns 'true' if \ref decl has been allocated a definition
/// *and* the definition was marked as completed. There are currently
/// situations in which LLDB marks a definition as `isCompleteDefinition`
/// while no definition was allocated. This function guards against those
/// situations.
static bool HasCompleteDefinition(clang::CXXRecordDecl *decl) {
return decl && decl->hasDefinition() && decl->isCompleteDefinition();
}

bool TypeSystemClang::IsPossibleDynamicType(lldb::opaque_compiler_type_t type,
CompilerType *dynamic_pointee_type,
bool check_cplusplus,
Expand Down Expand Up @@ -3732,8 +3742,9 @@ bool TypeSystemClang::IsPossibleDynamicType(lldb::opaque_compiler_type_t type,
if (check_cplusplus) {
clang::CXXRecordDecl *cxx_record_decl =
pointee_qual_type->getAsCXXRecordDecl();

if (cxx_record_decl) {
bool is_complete = cxx_record_decl->isCompleteDefinition();
bool is_complete = HasCompleteDefinition(cxx_record_decl);

if (is_complete)
success = cxx_record_decl->isDynamicClass();
Expand All @@ -3742,7 +3753,9 @@ bool TypeSystemClang::IsPossibleDynamicType(lldb::opaque_compiler_type_t type,
if (metadata)
success = metadata->GetIsDynamicCXXType();
else {
is_complete = GetType(pointee_qual_type).GetCompleteType();
// Make sure completion has actually completed the type.
is_complete = GetType(pointee_qual_type).GetCompleteType() &&
HasCompleteDefinition(cxx_record_decl);
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@adrian-prantl adrian-prantl Sep 6, 2024

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Which action could have changed the result of HasCompleteDefinition(cxx_record_decl) since line 3747?

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@Michael137 Michael137 Sep 6, 2024

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In the call to GetCompleteType (which does much more than the name suggests)

if (is_complete)
success = cxx_record_decl->isDynamicClass();
else
Expand Down Expand Up @@ -5478,8 +5491,12 @@ TypeSystemClang::GetNumChildren(lldb::opaque_compiler_type_t type,
llvm::cast<clang::RecordType>(qual_type.getTypePtr());
const clang::RecordDecl *record_decl = record_type->getDecl();
assert(record_decl);

// CXXBaseSpecifiers are stored on the definition. If we don't have
// one at this point that means we "completed" the type without actually
// having allocated a definition.
const clang::CXXRecordDecl *cxx_record_decl =
llvm::dyn_cast<clang::CXXRecordDecl>(record_decl);
llvm::dyn_cast<clang::CXXRecordDecl>(record_decl)->getDefinition();
if (cxx_record_decl) {
if (omit_empty_base_classes) {
// Check each base classes to see if it or any of its base classes
Expand Down