Fix C++23 compilation errors

This doesn't start building the project with C++23 yet (that needs
reach-out and discussion).

In C++23, instantiating ~unique_ptr<T> requires T to be a complete
type. So define some methods that instantiate this template later
(out-of-line).

Change-Id: I68d8ef73f4f7dc08b5762a73324cf98e8868b4d1
Reviewed-on: https://gn-review.googlesource.com/c/gn/+/22480
Reviewed-by: Takuto Ikuta <tikuta@google.com>
Commit-Queue: Victor Vianna <victorvianna@google.com>

src/gn/parse_tree.cc

diff --git a/src/gn/parse_tree.cc b/src/gn/parse_tree.cc
index e4fba38..8173c90 100644
--- a/src/gn/parse_tree.cc
+++ b/src/gn/parse_tree.cc
@@ -378,6 +378,10 @@
   return ret;
 }
 
+void AccessorNode::set_member(std::unique_ptr<IdentifierNode> i) {
+  member_ = std::move(i);
+}
+
 Value AccessorNode::ExecuteSubscriptAccess(Scope* scope, Err* err) const {
   const Value* base_value = scope->GetValue(base_.value(), true);
   if (!base_value) {
@@ -685,6 +689,10 @@
   return ret;
 }
 
+void BlockNode::set_end(std::unique_ptr<EndNode> e) {
+  end_ = std::move(e);
+}
+
 // ConditionNode --------------------------------------------------------------
 
 ConditionNode::ConditionNode() = default;
@@ -813,6 +821,10 @@
   return ret;
 }
 
+void FunctionCallNode::set_args(std::unique_ptr<ListNode> a) {
+  args_ = std::move(a);
+}
+
 void FunctionCallNode::SetNewLocation(int line_number) {
   Location func_old_loc = function_.location();
   Location func_new_loc =
@@ -954,6 +966,10 @@
   return ret;
 }
 
+void ListNode::set_end(std::unique_ptr<EndNode> e) {
+  end_ = std::move(e);
+}
+
 template <typename Comparator>
 void ListNode::SortList(Comparator comparator) {
   // Partitions first on BlockCommentNodes and sorts each partition separately.

src/gn/parse_tree.h

diff --git a/src/gn/parse_tree.h b/src/gn/parse_tree.h
index f3aeb58..471d6cb 100644
--- a/src/gn/parse_tree.h
+++ b/src/gn/parse_tree.h
@@ -183,7 +183,7 @@
   // The member is the identifier on the right hand side of the dot. Will be
   // null if the index is set.
   const IdentifierNode* member() const { return member_.get(); }
-  void set_member(std::unique_ptr<IdentifierNode> i) { member_ = std::move(i); }
+  void set_member(std::unique_ptr<IdentifierNode> i);
 
   void SetNewLocation(int line_number);
 
@@ -292,7 +292,7 @@
   static std::unique_ptr<BlockNode> NewFromJSON(const base::Value& value);
 
   void set_begin_token(const Token& t) { begin_token_ = t; }
-  void set_end(std::unique_ptr<EndNode> e) { end_ = std::move(e); }
+  void set_end(std::unique_ptr<EndNode> e);
   const EndNode* End() const { return end_.get(); }
 
   ResultMode result_mode() const { return result_mode_; }
@@ -391,7 +391,7 @@
   void set_function(Token t) { function_ = t; }
 
   const ListNode* args() const { return args_.get(); }
-  void set_args(std::unique_ptr<ListNode> a) { args_ = std::move(a); }
+  void set_args(std::unique_ptr<ListNode> a);
 
   const BlockNode* block() const { return block_.get(); }
   void set_block(std::unique_ptr<BlockNode> b) { block_ = std::move(b); }
@@ -458,7 +458,7 @@
 
   void set_begin_token(const Token& t) { begin_token_ = t; }
   const Token& Begin() const { return begin_token_; }
-  void set_end(std::unique_ptr<EndNode> e) { end_ = std::move(e); }
+  void set_end(std::unique_ptr<EndNode> e);
   const EndNode* End() const { return end_.get(); }
 
   void append_item(std::unique_ptr<ParseNode> s) {