[lldb] Add support for DW_TAG_immutable_type

[ljmf00]

I still need to add tests.

[teemperor]

Are the DWARFASTParserClang changes meant as a step towards making it parse D?

[ljmf00]

In D113634#3124042, @teemperor wrote:

Are the DWARFASTParserClang changes meant as a step towards making it parse D?

Yes, not only D but any language that currently falls here (https://github.com/llvm/llvm-project/blob/main/lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp#L106-L112). AFAIK, rust have immutable variables too. Since I'm working on a DWARFFASTParser for D this won't affect it in the future, but for languages like Rust that uses the Python API and rely on Clang DWARFParser, this could be beneficial.

[teemperor]

In D113634#3124401, @ljmf00 wrote:

In D113634#3124042, @teemperor wrote:

Are the DWARFASTParserClang changes meant as a step towards making it parse D?

Yes, not only D but any language that currently falls here (https://github.com/llvm/llvm-project/blob/main/lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp#L106-L112). AFAIK, rust have immutable variables too. Since I'm working on a DWARFFASTParser for D this won't affect it in the future, but for languages like Rust that uses the Python API and rely on Clang DWARFParser, this could be beneficial.

I know the change is well intended, but the Rust support is 100% untested and completely broken (it can't deal with pretty much any non-trivial program from my recollections). So I would split out the Clang changes (which probably require some longer discussion) and just keep the Type/DWARFDIe changes (which look good to me).

[ljmf00]

In D113634#3124428, @teemperor wrote:

In D113634#3124401, @ljmf00 wrote:

In D113634#3124042, @teemperor wrote:

Are the DWARFASTParserClang changes meant as a step towards making it parse D?

Yes, not only D but any language that currently falls here (https://github.com/llvm/llvm-project/blob/main/lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp#L106-L112). AFAIK, rust have immutable variables too. Since I'm working on a DWARFFASTParser for D this won't affect it in the future, but for languages like Rust that uses the Python API and rely on Clang DWARFParser, this could be beneficial.

I know the change is well intended, but the Rust support is 100% untested and completely broken (it can't deal with pretty much any non-trivial program from my recollections). So I would split out the Clang changes (which probably require some longer discussion) and just keep the Type/DWARFDIe changes (which look good to me).

Ok, makes sense to me. I'm going to make a separate patch, mark you as a subscriber and discuss this there.

lldb/include/lldb/Symbol/Type.h

enum EncodingDataType {
     /// This type is pointer to a type whose UID is m_encoding_uid.
     eEncodingIsPointerUID,
     /// This type is L value reference to a type whose UID is m_encoding_uid.
     eEncodingIsLValueReferenceUID,
     /// This type is R value reference to a type whose UID is m_encoding_uid.
     eEncodingIsRValueReferenceUID,
     /// This type is the type whose UID is m_encoding_uid as an atomic type.
     eEncodingIsAtomicUID,
+    /// This type is the type whose UID is m_encoding_uid with the immutable
+    /// qualifier added.
+    eEncodingIsImmutableUID,
     /// This type is the synthetic type whose UID is m_encoding_uid.
     eEncodingIsSyntheticUID
   };
 
   enum class ResolveState : unsigned char {
     Unresolved = 0,
     Forward = 1,
     Layout = 2,

lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp

TypeSP DWARFASTParserClang::ParseTypeFromDWARF(const SymbolContext &sc,
 
   switch (tag) {
   case DW_TAG_typedef:
   case DW_TAG_base_type:
   case DW_TAG_pointer_type:
   case DW_TAG_reference_type:
   case DW_TAG_rvalue_reference_type:
   case DW_TAG_const_type:
+  case DW_TAG_immutable_type:
   case DW_TAG_restrict_type:
   case DW_TAG_volatile_type:
   case DW_TAG_atomic_type:
   case DW_TAG_unspecified_type: {
     type_sp = ParseTypeModifier(sc, die, attrs);
     break;
   }
 
case DW_TAG_rvalue_reference_type:
     encoding_data_type = Type::eEncodingIsRValueReferenceUID;
     break;
   case DW_TAG_typedef:
     encoding_data_type = Type::eEncodingIsTypedefUID;
     break;
   case DW_TAG_const_type:
     encoding_data_type = Type::eEncodingIsConstUID;
     break;
+  case DW_TAG_immutable_type:
+    encoding_data_type = Type::eEncodingIsImmutableUID;
+    break;
   case DW_TAG_restrict_type:
     encoding_data_type = Type::eEncodingIsRestrictUID;
     break;
   case DW_TAG_volatile_type:
     encoding_data_type = Type::eEncodingIsVolatileUID;
     break;
   case DW_TAG_atomic_type:
     encoding_data_type = Type::eEncodingIsAtomicUID;

lldb/source/Plugins/SymbolFile/DWARF/DWARFDIE.cpp

case DW_TAG_base_type:
     s.PutCString("base ");
     break;
   case DW_TAG_class_type:
     s.PutCString("class ");
     break;
   case DW_TAG_const_type:
     s.PutCString("const ");
     break;
+  case DW_TAG_immutable_type:
+    s.PutCString("immutable ");
+    break;
   case DW_TAG_enumeration_type:
     s.PutCString("enum ");
     break;
   case DW_TAG_file_type:
     s.PutCString("file ");
     break;
   case DW_TAG_interface_type:
     s.PutCString("interface ");