Allow implicitly converting IntLiteralExpr to other int types

src/ast.h

@@ -42,8 +42,15 @@ namespace AST {
     class IntLiteralExpression : public Expression {
     private:
         int m_value;
+        std::shared_ptr<types::Type> m_ty;
     public:
-        IntLiteralExpression(token::Metadata meta, int value) : Expression{ meta }, m_value{ value } {}
+        IntLiteralExpression(token::Metadata meta, int value)
+            : Expression{ meta }
+            , m_value{ value }
+            , m_ty{ { std::shared_ptr<types::Type>{
+                new types::FundamentalType{types::FundamentalTypeKind::Int}
+            } } } {
+        }
         virtual ~IntLiteralExpression() override = default;
         virtual std::string formatted() override;
         virtual codegen::StackValue codegen(codegen::Builder& builder, codegen::Scope& scope) override;

src/codegen.cpp

@@ -19,11 +19,10 @@ namespace AST {
     codegen::StackValue IntLiteralExpression::codegen(codegen::Builder& builder, codegen::Scope&) {
         auto ty = builder.builder->getInt32Ty();
 
-        auto stack_type = new types::FundamentalType{ types::FundamentalTypeKind::Int };
 
         return codegen::StackValue{
             llvm::ConstantInt::get(ty, this->m_value),
-            std::unique_ptr<types::Type>{stack_type}
+            this->m_ty,
         };
     }
 

src/typechecker.cpp

@@ -43,11 +43,24 @@ namespace AST {
     std::shared_ptr<types::Type> IntLiteralExpression::typecheck(
         typecheck::State&,
         typecheck::Scope&,
-        std::optional<std::shared_ptr<types::Type>>
+        std::optional<std::shared_ptr<types::Type>> expected_ty
     ) {
-        return std::shared_ptr<types::Type>{
-            new types::FundamentalType{ types::FundamentalTypeKind::Int }
-        };
+        // Allow implicitly converting IntLiteralExpression to other types
+        // representable by integers.
+        if (expected_ty) {
+            if ((*expected_ty)->m_kind == types::TypeKind::Fundamental) {
+                auto ty = dynamic_cast<types::FundamentalType*>((*expected_ty).get());
+                if (
+                    ty->m_ty == types::FundamentalTypeKind::Bool
+                    || ty->m_ty == types::FundamentalTypeKind::Char
+                    || ty->m_ty == types::FundamentalTypeKind::Int
+                    ) {
+                    this->m_ty = *expected_ty;
+                }
+            }
+        }
+
+        return this->m_ty;
     }
 
     std::shared_ptr<types::Type> StringLiteralExpression::typecheck(

test.c

@@ -6,7 +6,7 @@ int fibonacci(int n) {
     return fibonacci(n - 1) + fibonacci(n - 2);
 }
 
-int main() {
+char main() {
     printf("10th fibonacci number is %d!", fibonacci(10));
     return 0;
 }