Test cases

- Added two new checks for checking the return type of a function and matching a `ReturnStmt`'s expression's type to it

.github/workflows/d.yml

@@ -355,6 +355,19 @@ jobs:
           else
               exit 1
           fi
+
+      - name: Function return expression coercion (good)
+        run: ./tlang typecheck source/tlang/testing/simple_function_return_type_check_good.t
+      - name: Function return expression coercion (bad)
+        run:
+          set +e
+          ./tlang typecheck source/tlang/testing/simple_function_return_type_check_bad.t
+          if [ $? = 255 ]
+          then
+              exit 0
+          else
+              exit 1
+          fi
         
   emit:
     needs: [build, unittests]

source/tlang/testing/simple_function_return_type_check_bad.t

@@ -0,0 +1,6 @@
+module simple_function_return_type_check_bad;
+
+ubyte factorial(ubyte i)
+{
+    return 256;
+}

source/tlang/testing/simple_function_return_type_check_good.t

@@ -0,0 +1,6 @@
+module simple_function_return_type_check_good;
+
+ubyte factorial(ubyte i)
+{
+    return 1;
+}