Add typechecking for if expressions

1 files changed, 30 insertions, 0 deletions

diff --git a/src/main.c b/src/main.c
index a66a40c..df2f687 100644
--- a/src/main.c
+++ b/src/main.c
@@ -253,6 +253,36 @@ type_inference(Analyzer *a, Node *node, TypeScope *scope) {
             }
             return node->type;
         } break;
+        case NODE_IF: {
+            Type type = type_inference(a, node->cond_if, scope);
+            if (!str_eq(type, cstr("bool"))) {
+                emit_semantic_error(
+                    a, node->cond_if,
+                    cstr("non boolean expression on if condition"));
+                return cstr("");
+            }
+            if (node->cond_expr->kind == NODE_BLOCK) {
+                node->type = type_inference(a, node->cond_expr, scope);
+            } else {
+                TypeScope *next = typescope_alloc(a, scope);
+                node->type = type_inference(a, node->cond_expr, next);
+            }
+            if (node->cond_else) {
+                Type else_type;
+                if (node->cond_else->kind == NODE_BLOCK) {
+                    else_type = type_inference(a, node->cond_else, scope);
+                } else {
+                    TypeScope *next = typescope_alloc(a, scope);
+                    else_type = type_inference(a, node->cond_else, next);
+                }
+                if (!str_eq(node->type, else_type)) {
+                    emit_semantic_error(
+                        a, node,
+                        cstr("mismatch types for if/else branches"));
+                    return cstr("");
+                }
+            }
+        } break;
         case NODE_TRUE:
         case NODE_FALSE: {
             node->type = cstr("bool");