Change GetNumChildren()/CalculateNumChildren() methods return llvm::Expected (#84219)

Change GetNumChildren()/CalculateNumChildren() methods return
llvm::Expected

This is an NFC change that does not yet add any error handling or change
any code to return any errors.

This is the second big change in the patch series started with
#83501

A follow-up PR will wire up error handling.

Author: adrian-prantl

lldb/include/lldb/Core/ValueObject.h

@@ -476,7 +476,13 @@ class ValueObject {
 
   virtual size_t GetIndexOfChildWithName(llvm::StringRef name);
 
-  uint32_t GetNumChildren(uint32_t max = UINT32_MAX);
+  llvm::Expected<uint32_t> GetNumChildren(uint32_t max = UINT32_MAX);
+  /// Like \c GetNumChildren but returns 0 on error.  You probably
+  /// shouldn't be using this function. It exists primarily to ease the
+  /// transition to more pervasive error handling while not all APIs
+  /// have been updated.
+  uint32_t GetNumChildrenIgnoringErrors(uint32_t max = UINT32_MAX);
+  bool HasChildren() { return GetNumChildrenIgnoringErrors() > 0; }
 
   const Value &GetValue() const { return m_value; }
 
@@ -958,7 +964,8 @@ class ValueObject {
                                           int32_t synthetic_index);
 
   /// Should only be called by ValueObject::GetNumChildren().
-  virtual uint32_t CalculateNumChildren(uint32_t max = UINT32_MAX) = 0;
+  virtual llvm::Expected<uint32_t>
+  CalculateNumChildren(uint32_t max = UINT32_MAX) = 0;
 
   void SetNumChildren(uint32_t num_children);
 

lldb/include/lldb/Core/ValueObjectCast.h

@@ -33,7 +33,7 @@ class ValueObjectCast : public ValueObject {
 
   std::optional<uint64_t> GetByteSize() override;
 
-  uint32_t CalculateNumChildren(uint32_t max) override;
+  llvm::Expected<uint32_t> CalculateNumChildren(uint32_t max) override;
 
   lldb::ValueType GetValueType() const override;
 

lldb/include/lldb/Core/ValueObjectChild.h

@@ -39,7 +39,7 @@ class ValueObjectChild : public ValueObject {
 
   lldb::ValueType GetValueType() const override;
 
-  uint32_t CalculateNumChildren(uint32_t max) override;
+  llvm::Expected<uint32_t> CalculateNumChildren(uint32_t max) override;
 
   ConstString GetTypeName() override;
 

lldb/include/lldb/Core/ValueObjectConstResult.h

@@ -67,7 +67,7 @@ class ValueObjectConstResult : public ValueObject {
 
   lldb::ValueType GetValueType() const override;
 
-  uint32_t CalculateNumChildren(uint32_t max) override;
+  llvm::Expected<uint32_t> CalculateNumChildren(uint32_t max) override;
 
   ConstString GetTypeName() override;
 

lldb/include/lldb/Core/ValueObjectDynamicValue.h

@@ -43,7 +43,7 @@ class ValueObjectDynamicValue : public ValueObject {
 
   ConstString GetDisplayTypeName() override;
 
-  uint32_t CalculateNumChildren(uint32_t max) override;
+  llvm::Expected<uint32_t> CalculateNumChildren(uint32_t max) override;
 
   lldb::ValueType GetValueType() const override;
 

lldb/include/lldb/Core/ValueObjectMemory.h

@@ -47,7 +47,7 @@ class ValueObjectMemory : public ValueObject {
 
   ConstString GetDisplayTypeName() override;
 
-  uint32_t CalculateNumChildren(uint32_t max) override;
+  llvm::Expected<uint32_t> CalculateNumChildren(uint32_t max) override;
 
   lldb::ValueType GetValueType() const override;
 

lldb/include/lldb/Core/ValueObjectRegister.h

@@ -47,7 +47,7 @@ class ValueObjectRegisterSet : public ValueObject {
 
   ConstString GetQualifiedTypeName() override;
 
-  uint32_t CalculateNumChildren(uint32_t max) override;
+  llvm::Expected<uint32_t> CalculateNumChildren(uint32_t max) override;
 
   ValueObject *CreateChildAtIndex(size_t idx, bool synthetic_array_member,
                                   int32_t synthetic_index) override;
@@ -95,7 +95,7 @@ class ValueObjectRegister : public ValueObject {
 
   ConstString GetTypeName() override;
 
-  uint32_t CalculateNumChildren(uint32_t max) override;
+  llvm::Expected<uint32_t> CalculateNumChildren(uint32_t max) override;
 
   bool SetValueFromCString(const char *value_str, Status &error) override;
 

lldb/include/lldb/Core/ValueObjectSyntheticFilter.h

@@ -47,7 +47,7 @@ class ValueObjectSynthetic : public ValueObject {
 
   bool MightHaveChildren() override;
 
-  uint32_t CalculateNumChildren(uint32_t max) override;
+  llvm::Expected<uint32_t> CalculateNumChildren(uint32_t max) override;
 
   lldb::ValueType GetValueType() const override;
 

lldb/include/lldb/Core/ValueObjectVTable.h

@@ -64,7 +64,7 @@ class ValueObjectVTable : public ValueObject {
 
   std::optional<uint64_t> GetByteSize() override;
 
-  uint32_t CalculateNumChildren(uint32_t max) override;
+  llvm::Expected<uint32_t> CalculateNumChildren(uint32_t max) override;
 
   ValueObject *CreateChildAtIndex(size_t idx, bool synthetic_array_member,
                                   int32_t synthetic_index) override;

lldb/include/lldb/Core/ValueObjectVariable.h

@@ -46,7 +46,7 @@ class ValueObjectVariable : public ValueObject {
 
   ConstString GetDisplayTypeName() override;
 
-  uint32_t CalculateNumChildren(uint32_t max) override;
+  llvm::Expected<uint32_t> CalculateNumChildren(uint32_t max) override;
 
   lldb::ValueType GetValueType() const override;