Unify the return value of GetByteSize to an llvm::Optional<uint64_t> (NFC-ish)

This cleanup patch unifies all methods called GetByteSize() in the
ValueObject hierarchy to return an optional, like the methods in
CompilerType do. This means fewer magic 0 values, which could fix bugs
down the road in languages where types can have a size of zero, such
as Swift and C (but not C++).

Differential Revision: https://reviews.llvm.org/D84285

This re-lands the patch with bogus :m_byte_size(0) initalizations removed.

1 files changed, 8 insertions, 13 deletions

diff --git a/lldb/source/Core/ValueObjectConstResult.cpp b/lldb/source/Core/ValueObjectConstResult.cpp
index 8d84f8e62ccc..ceb4491f8666 100644
--- a/lldb/source/Core/ValueObjectConstResult.cpp
+++ b/lldb/source/Core/ValueObjectConstResult.cpp
@@ -40,8 +40,7 @@ ValueObjectConstResult::ValueObjectConstResult(ExecutionContextScope *exe_scope,
                                                ByteOrder byte_order,
                                                uint32_t addr_byte_size,
                                                lldb::addr_t address)
-    : ValueObject(exe_scope, manager), m_type_name(), m_byte_size(0),
-      m_impl(this, address) {
+    : ValueObject(exe_scope, manager), m_impl(this, address) {
   SetIsConstant();
   SetValueIsValid(true);
   m_data.SetByteOrder(byte_order);
@@ -64,8 +63,7 @@ ValueObjectConstResult::ValueObjectConstResult(
     ExecutionContextScope *exe_scope, ValueObjectManager &manager,
     const CompilerType &compiler_type, ConstString name,
     const DataExtractor &data, lldb::addr_t address)
-    : ValueObject(exe_scope, manager), m_type_name(), m_byte_size(0),
-      m_impl(this, address) {
+    : ValueObject(exe_scope, manager), m_impl(this, address) {
   m_data = data;
 
   if (!m_data.GetSharedDataBuffer()) {
@@ -112,8 +110,7 @@ ValueObjectConstResult::ValueObjectConstResult(
     const CompilerType &compiler_type, ConstString name,
     const lldb::DataBufferSP &data_sp, lldb::ByteOrder data_byte_order,
     uint32_t data_addr_size, lldb::addr_t address)
-    : ValueObject(exe_scope, manager), m_type_name(), m_byte_size(0),
-      m_impl(this, address) {
+    : ValueObject(exe_scope, manager), m_impl(this, address) {
   m_data.SetByteOrder(data_byte_order);
   m_data.SetAddressByteSize(data_addr_size);
   m_data.SetData(data_sp);
@@ -143,7 +140,7 @@ ValueObjectConstResult::ValueObjectConstResult(
     ExecutionContextScope *exe_scope, ValueObjectManager &manager,
     const CompilerType &compiler_type, ConstString name, lldb::addr_t address,
     AddressType address_type, uint32_t addr_byte_size)
-    : ValueObject(exe_scope, manager), m_type_name(), m_byte_size(0),
+    : ValueObject(exe_scope, manager), m_type_name(),
       m_impl(this, address) {
   m_value.GetScalar() = address;
   m_data.SetAddressByteSize(addr_byte_size);
@@ -179,8 +176,7 @@ ValueObjectSP ValueObjectConstResult::Create(ExecutionContextScope *exe_scope,
 ValueObjectConstResult::ValueObjectConstResult(ExecutionContextScope *exe_scope,
                                                ValueObjectManager &manager,
                                                const Status &error)
-    : ValueObject(exe_scope, manager), m_type_name(), m_byte_size(0),
-      m_impl(this) {
+    : ValueObject(exe_scope, manager), m_impl(this) {
   m_error = error;
   SetIsConstant();
 }
@@ -189,8 +185,7 @@ ValueObjectConstResult::ValueObjectConstResult(ExecutionContextScope *exe_scope,
                                                ValueObjectManager &manager,
                                                const Value &value,
                                                ConstString name, Module *module)
-    : ValueObject(exe_scope, manager), m_type_name(), m_byte_size(0),
-      m_impl(this) {
+    : ValueObject(exe_scope, manager), m_impl(this) {
   m_value = value;
   m_name = name;
   ExecutionContext exe_ctx;
@@ -208,9 +203,9 @@ lldb::ValueType ValueObjectConstResult::GetValueType() const {
   return eValueTypeConstResult;
 }
 
-uint64_t ValueObjectConstResult::GetByteSize() {
+llvm::Optional<uint64_t> ValueObjectConstResult::GetByteSize() {
   ExecutionContext exe_ctx(GetExecutionContextRef());
-  if (m_byte_size == 0) {
+  if (!m_byte_size) {
     if (auto size =
         GetCompilerType().GetByteSize(exe_ctx.GetBestExecutionContextScope()))
       SetByteSize(*size);