[Lldb-commits] [lldb] [clang][AST] Added assert to prevent infinite recursion in computing layout (PR #154123)

[via lldb-commits]

https://github.com/tgs-sc updated https://github.com/llvm/llvm-project/pull/154123

>From f19ba133d67af221c8ccba6d697d1b3cac88c943 Mon Sep 17 00:00:00 2001
From: Timur Golubovich <timur.golubovich at syntacore.com>
Date: Mon, 18 Aug 2025 17:29:01 +0300
Subject: [PATCH] [lldb][DWARFASTParserClang] Added a check for the
 specialization existence

While debugging an application with incorrect dwarf information, where
DW_TAG_template_value_parameter was 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.
---
 .../SymbolFile/DWARF/DWARFASTParserClang.cpp     | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

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);
   }