Inline type alias & rename data member

Since an item of a compound statement is no longer an `std::variant`, we
no longer use a type alias to simplify the type. Additionally, the data
member has been renamed to remove the word `item`, which is a technical
term used during parsing.

include/ast.hpp

@@ -211,14 +211,13 @@ struct LoopInitNode : public AstNode {
 };
 
 struct CompoundStmtNode : public StmtNode {
-  using Item = std::unique_ptr<StmtNode>;
-  CompoundStmtNode(Location loc, std::vector<Item> items)
-      : StmtNode{loc}, items{std::move(items)} {}
+  CompoundStmtNode(Location loc, std::vector<std::unique_ptr<StmtNode>> stmts)
+      : StmtNode{loc}, stmts{std::move(stmts)} {}
 
   void Accept(NonModifyingVisitor&) const override;
   void Accept(ModifyingVisitor&) override;
 
-  std::vector<Item> items;
+  std::vector<std::unique_ptr<StmtNode>> stmts;
 };
 
 /// @brief Root of the entire program.

parser.y

@@ -131,7 +131,7 @@ std::unique_ptr<Type> ResolveType(std::unique_ptr<Type> resolved_type,
 %nterm <std::unique_ptr<LoopInitNode>> loop_init
 %nterm <std::unique_ptr<StmtNode>> stmt jump_stmt selection_stmt labeled_stmt block_item
 %nterm <std::unique_ptr<CompoundStmtNode>> compound_stmt
-%nterm <std::vector<CompoundStmtNode::Item>> block_item_list block_item_list_opt
+%nterm <std::vector<std::unique_ptr<StmtNode>>> block_item_list block_item_list_opt
 
 // Resolve the ambiguity in the "dangling-else" grammar.
 // Example: IF LEFT_PAREN expr RIGHT_PAREN IF LEFT_PAREN expr RIGHT_PAREN stmt • ELSE stmt
@@ -198,12 +198,12 @@ compound_stmt: LEFT_CURLY block_item_list_opt RIGHT_CURLY {
 
 block_item_list_opt: block_item_list { $$ = $1; }
   | epsilon {
-    $$ = std::vector<CompoundStmtNode::Item>{};
+    $$ = std::vector<std::unique_ptr<StmtNode>>{};
   }
   ;
 
 block_item_list: block_item {
-    $$ = std::vector<CompoundStmtNode::Item>{};
+    $$ = std::vector<std::unique_ptr<StmtNode>>{};
     $$.push_back($1);
   }
   | block_item_list block_item {

src/ast_dumper.cpp

@@ -178,8 +178,8 @@ void AstDumper::Visit(const CompoundStmtNode& compound_stmt) {
   std::cout << indenter_.Indent() << "CompoundStmtNode <" << compound_stmt.loc
             << ">\n";
   indenter_.IncreaseLevel();
-  for (const auto& item : compound_stmt.items) {
-    item->Accept(*this);
+  for (const auto& stmt : compound_stmt.stmts) {
+    stmt->Accept(*this);
   }
   indenter_.DecreaseLevel();
 }

src/qbe_ir_generator.cpp

@@ -273,8 +273,8 @@ void QbeIrGenerator::Visit(const CompoundStmtNode& compound_stmt) {
   // because it doesn't know whether it is a if statement body or a function.
   // Thus, by moving label creation to an upper level, each block can have its
   // correct starting label.
-  for (const auto& item : compound_stmt.items) {
-    item->Accept(*this);
+  for (const auto& stmt : compound_stmt.stmts) {
+    stmt->Accept(*this);
   }
 }
 

src/type_checker.cpp

@@ -200,8 +200,8 @@ void TypeChecker::Visit(LoopInitNode& loop_init) {
 
 void TypeChecker::Visit(CompoundStmtNode& compound_stmt) {
   env_.PushScope(ScopeKind::kBlock);
-  for (auto& item : compound_stmt.items) {
-    item->Accept(*this);
+  for (auto& stmt : compound_stmt.stmts) {
+    stmt->Accept(*this);
   }
   env_.PopScope();
 }