[Lldb-commits] [lldb] 76edf72 - Reland: [lldb] Fix crash missing MSInheritanceAttr with DWARF on Windows (#112928)

[Stefan Gränitz via lldb-commits]

Author: Stefan Gränitz
Date: 2024-10-24T13:47:15+02:00
New Revision: 76edf72501cd6f66788c631fada95972a797a4a6

URL: https://github.com/llvm/llvm-project/commit/76edf72501cd6f66788c631fada95972a797a4a6
DIFF: https://github.com/llvm/llvm-project/commit/76edf72501cd6f66788c631fada95972a797a4a6.diff

LOG: Reland: [lldb] Fix crash missing MSInheritanceAttr with DWARF on Windows (#112928)

Member pointers refer to data or function members of a `CXXRecordDecl`,
which require a `MSInheritanceAttr` in order to be complete. Without that
we cannot calculate the size of a member pointer in memory. The attempt
has been causing a crash further down in the clang AST context. In order
to implement the feature, DWARF will need a new attribtue to convey the
information. For the moment, this patch teaches LLDB to handle to
situation and avoid the crash.

Added: 
    lldb/test/Shell/SymbolFile/DWARF/x86/member-pointers.cpp

Modified: 
    lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp

Removed: 
    


################################################################################
diff  --git a/lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp b/lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp
index a57cd8efce8a11..f5063175d6e070 100644
--- a/lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp
+++ b/lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp
@@ -2771,6 +2771,9 @@ static bool GetCompleteQualType(clang::ASTContext *ast,
         ast, llvm::cast<clang::AttributedType>(qual_type)->getModifiedType(),
         allow_completion);
 
+  case clang::Type::MemberPointer:
+    return !qual_type.getTypePtr()->isIncompleteType();
+
   default:
     break;
   }

diff  --git a/lldb/test/Shell/SymbolFile/DWARF/x86/member-pointers.cpp b/lldb/test/Shell/SymbolFile/DWARF/x86/member-pointers.cpp
new file mode 100644
index 00000000000000..c7bd95774d33f7
--- /dev/null
+++ b/lldb/test/Shell/SymbolFile/DWARF/x86/member-pointers.cpp
@@ -0,0 +1,24 @@
+// REQUIRES: lld
+
+// Itanium ABI:
+// RUN: %clang --target=x86_64-pc-linux -gdwarf -c -o %t_linux.o %s
+// RUN: %lldb -f %t_linux.o -b -o "target variable mp" | FileCheck %s
+//
+// CHECK: (char SI::*) mp = 0x0000000000000000
+
+// Microsoft ABI:
+// RUN: %clang_cl --target=x86_64-windows-msvc -c -gdwarf -o %t_win.obj -- %s
+// RUN: lld-link /out:%t_win.exe %t_win.obj /nodefaultlib /entry:main /debug
+// RUN: %lldb -f %t_win.exe -b -o "target variable mp" | FileCheck --check-prefix=CHECK-MSVC %s
+//
+// DWARF has no representation of MSInheritanceAttr, so we cannot determine the size
+// of member-pointers yet. For the moment, make sure we don't crash on such variables.
+// CHECK-MSVC: error: Unable to determine byte size.
+
+struct SI {
+  char si;
+};
+
+char SI::*mp = &SI::si;
+
+int main() { return 0; }