https://github.com/tgs-sc created
https://github.com/llvm/llvm-project/pull/154123
[lldb][DWARFASTParserClang] Added a check for the specialization existence
While debugging an application with incorrect dwarf information, where
DW_TAG_template_value_parameter were lost, I found that lldb does not
check that the corresponding specialization exists. As a result, at the
stage when ASTImporter works, the type is completed in such a way that
it inherits from itself. And during the calculation of layout, an
infinite recursion occurs. To catch this error, I added a corresponding
check
at the stage of restoring the type from dwarf information. I also added a
trivial assert in clang to check that the class does not inherit from
itself.
>From 25d756bbfb5da66375f09cb71d89159e7521f5af Mon Sep 17 00:00:00 2001
From: Timur Golubovich <timur.golubov...@syntacore.com>
Date: Mon, 18 Aug 2025 17:29:01 +0300
Subject: [PATCH] [clang][AST] Added assert to prevent infinite recursion
in computing layout [lldb][DWARFASTParserClang] Added a check for the
specialization existence
While debugging an application with incorrect dwarf information, where
DW_TAG_template_value_parameter were lost, I found that lldb does not
check that the corresponding specialization exists. As a result, at the
stage when ASTImporter works, the type is completed in such a way that
it inherits from itself. And during the calculation of layout, an
infinite recursion occurs. To catch this error, I added a corresponding
check
at the stage of restoring the type from dwarf information. I also added a
trivial assert in clang to check that the class does not inherit from
itself.
---
clang/lib/AST/RecordLayoutBuilder.cpp | 2 ++
.../SymbolFile/DWARF/DWARFASTParserClang.cpp | 16 ++++++++++++++++
2 files changed, 18 insertions(+)
diff --git a/clang/lib/AST/RecordLayoutBuilder.cpp
b/clang/lib/AST/RecordLayoutBuilder.cpp
index 6d819031cbef4..93571543f1c7d 100644
--- a/clang/lib/AST/RecordLayoutBuilder.cpp
+++ b/clang/lib/AST/RecordLayoutBuilder.cpp
@@ -187,6 +187,8 @@ void EmptySubobjectMap::ComputeEmptySubobjectSizes() {
// Check the bases.
for (const CXXBaseSpecifier &Base : Class->bases()) {
const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
+ // Assert to prevent infinite recursion.
+ assert(BaseDecl != Class && "Class cannot inherit from itself.");
CharUnits EmptySize;
const ASTRecordLayout &Layout = Context.getASTRecordLayout(BaseDecl);
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp
b/lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp
index c76d67b47b336..6643751cd237a 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp
@@ -1873,6 +1873,22 @@ DWARFASTParserClang::ParseStructureLikeDIE(const
SymbolContext &sc,
clang_type =
m_ast.CreateClassTemplateSpecializationType(class_specialization_decl);
+ // Try to find an existing specialization with these template arguments and
+ // template parameter list.
+ void *InsertPos = nullptr;
+ if
(!class_template_decl->findSpecialization(template_param_infos.GetArgs(),
+ InsertPos))
+ // Add this specialization to the class template.
+ class_template_decl->AddSpecialization(class_specialization_decl,
+ InsertPos);
+ else {
+ dwarf->GetObjectFile()->GetModule()->ReportError(
+ "SymbolFileDWARF({0:p}) - Specialization for "
+ "clang::ClassTemplateDecl({1:p}) already exists.",
+ static_cast<void *>(this), static_cast<void *>(class_template_decl));
+ return TypeSP();
+ }
+
m_ast.SetMetadata(class_template_decl, metadata);
m_ast.SetMetadata(class_specialization_decl, metadata);
}
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