From 902610aaea83d00f35248e05cee5d1f5d0f9317f Mon Sep 17 00:00:00 2001
From: Sofia <sofia@teascade.net>
Date: Mon, 13 Apr 2026 00:54:14 +0300
Subject: [PATCH] Add statement typecheckings

---
 src/typechecker.cpp | 34 +++++++++++++++++++++++++++++-----
 src/typechecker.h   |  5 +++--
 2 files changed, 32 insertions(+), 7 deletions(-)

diff --git a/src/typechecker.cpp b/src/typechecker.cpp
index c4aed66..e46fcb3 100644
--- a/src/typechecker.cpp
+++ b/src/typechecker.cpp
@@ -45,22 +45,46 @@ namespace AST {
     }
 
     void ReturnStatement::typecheck(typecheck::State& state, typecheck::Scope& scope) {
-        throw CompileError("TODO", {});
+        this->m_expr->typecheck(state, scope, scope.return_ty);
     }
 
     void InitializationStatement::typecheck(typecheck::State& state, typecheck::Scope& scope) {
-        throw CompileError("TODO", {});
+        if (this->m_expr) {
+            (*this->m_expr)->typecheck(state, scope, this->m_type);
+        }
+        scope.symbols[this->m_name] = this->m_type;
     }
 
     void ExpressionStatement::typecheck(typecheck::State& state, typecheck::Scope& scope) {
-        throw CompileError("TODO", {});
+        this->m_expr->typecheck(state, scope, {});
     }
 
     void IfStatement::typecheck(typecheck::State& state, typecheck::Scope& scope) {
-        throw CompileError("TODO", {});
+        auto bool_ty_ptr = new types::FundamentalType{ types::FundamentalTypeKind::Bool };
+        this->m_condition->typecheck(state, scope, std::shared_ptr<types::Type>{ bool_ty_ptr });
+
+        this->m_then->typecheck(state, scope);
+        if (this->m_else) {
+            (*this->m_else)->typecheck(state, scope);
+        }
     }
 
     void Function::typecheck(typecheck::State& state, typecheck::Scope& scope) {
-        throw CompileError("TODO", {});
+        auto return_ty = this->m_return_ty;
+        std::vector<std::shared_ptr<types::Type>> param_tys{};
+        for (auto& param : this->m_params) {
+            param_tys.push_back(param.second);
+        }
+
+        auto function_ty = new types::FunctionType{ return_ty, param_tys, this->m_is_vararg };
+        scope.symbols[this->m_name] = std::shared_ptr<types::Type>{ function_ty };
+
+        typecheck::Scope inner{ scope };
+
+        if (this->m_statements) {
+            for (auto& statement : *this->m_statements) {
+                statement->typecheck(state, inner);
+            }
+        }
     }
 }
\ No newline at end of file
diff --git a/src/typechecker.h b/src/typechecker.h
index a32e230..6256338 100644
--- a/src/typechecker.h
+++ b/src/typechecker.h
@@ -9,7 +9,7 @@
 namespace typecheck {
     enum class TypecheckResult {
         /// @brief The types match perfectly (enough)
-        Suitable,
+        Ok,
         /// @brief The original type can be implicitly cast into the given type
         Castable,
         /// @brief The types are totally incompatible
@@ -17,7 +17,8 @@ namespace typecheck {
     };
 
     struct Scope {
-        std::map<std::string, types::Type> symbols;
+        std::map<std::string, std::shared_ptr<types::Type>> symbols;
+        std::optional<std::shared_ptr<types::Type>> return_ty;
     };
 
     struct State {