[Tolk] Compiler built-in __expect_type() for testing purposes

Currently, tolk-tester can test various "output" of the compiler:
pass input and check output, validate fif codegen, etc.
But it can not test compiler internals and AST representation.

I've added an ability to have special functions to check/expose
internal compiler state. The first (and the only now) is:
> __expect_type(some_expr, "<type>");
Such a call has special treatment in a compilation process.
Compilation fails if this expression doesn't have requested type.

It's intended to be used in tests only. Not present in stdlib.

tolk/builtins.cpp

@@ -1255,6 +1255,13 @@ void define_builtins() {
   define_builtin_func("debugDumpStack", {}, Unit, nullptr,
                                 AsmOp::Custom("DUMPSTK", 0, 0),
                                 0);
+
+  // functions not presented in stdlib at all
+  // used in tolk-tester to check/expose internal compiler state
+  // each of them is handled in a special way, search by its name
+  define_builtin_func("__expect_type", {TypeDataUnknown::create(), Slice}, Unit, nullptr,
+                                AsmOp::Nop(),
+                                FunctionData::flagMarkedAsPure);
 }
 
 }  // namespace tolk

tolk/lexer.cpp

@@ -555,6 +555,15 @@ Lexer::Lexer(const SrcFile* file)
   next();
 }
 
+Lexer::Lexer(std::string_view text)
+  : file(nullptr)
+  , p_start(text.data())
+  , p_end(p_start + text.size())
+  , p_next(p_start)
+  , location() {
+  next();
+}
+
 void Lexer::next() {
   while (cur_token_idx == last_token_idx && !is_eof()) {
     update_location();
@@ -563,7 +572,7 @@ void Lexer::next() {
     }
   }
   if (is_eof()) {
-    add_token(tok_eof, file->text);
+    add_token(tok_eof, "");
   }
   cur_token = tokens_circularbuf[++cur_token_idx & 7];
 }

tolk/lexer.h

@@ -173,6 +173,7 @@ public:
   };
 
   explicit Lexer(const SrcFile* file);
+  explicit Lexer(std::string_view text);
   Lexer(const Lexer&) = delete;
   Lexer &operator=(const Lexer&) = delete;
 

tolk/pipe-infer-types-and-calls.cpp

@@ -240,6 +240,24 @@ public:
   TypePtr get_result() const { return unified_result; }
 };
 
+// handle __expect_type(expr, "type") call
+// this is used in compiler tests
+GNU_ATTRIBUTE_NOINLINE GNU_ATTRIBUTE_COLD
+static void handle_possible_compiler_internal_call(const FunctionData* current_function, V<ast_function_call> v) {
+  const FunctionData* fun_ref = v->fun_maybe;
+  tolk_assert(fun_ref && fun_ref->is_builtin_function());
+  static_cast<void>(current_function);
+
+  if (fun_ref->name == "__expect_type") {
+    tolk_assert(v->get_num_args() == 2);
+    TypePtr expected_type = parse_type_from_string(v->get_arg(1)->get_expr()->as<ast_string_const>()->str_val);
+    TypePtr expr_type = v->get_arg(0)->inferred_type;
+    if (expected_type != expr_type) {
+      v->error("__expect_type failed: expected " + to_string(expected_type) + ", got " + to_string(expr_type));
+    }
+  }
+}
+
 /*
  * This class handles all types of AST vertices and traverses them, filling all AnyExprV::inferred_type.
  * Note, that it isn't derived from ASTVisitor, it has manual `switch` over all existing vertex types.
@@ -974,6 +992,9 @@ class InferCheckTypesAndCallsAndFieldsVisitor final {
     TypePtr inferred_type = dot_obj && fun_ref->does_return_self() ? dot_obj->inferred_type : fun_ref->inferred_return_type;
     assign_inferred_type(v, inferred_type);
     assign_inferred_type(callee, fun_ref->inferred_full_type);
+    if (fun_ref->is_builtin_function() && fun_ref->name[0] == '_') {
+      handle_possible_compiler_internal_call(current_function, v);
+    }
     // note, that mutate params don't affect typing, they are handled when converting to IR
   }
 

tolk/type-system.cpp

@@ -651,11 +651,6 @@ static TypePtr parse_simple_type(Lexer& lex) {
       std::vector<TypePtr> items = parse_nested_type_list(lex, tok_opbracket, "`[`", tok_clbracket, "`]` or `,`");
       return TypeDataTypedTuple::create(std::move(items));
     }
-    case tok_fun: {
-      lex.next();
-      std::vector<TypePtr> params_types = parse_nested_type_list_in_parenthesis(lex);
-      lex.expect(tok_arrow, "`->`");
-    }
     default:
       lex.unexpected("<type>");
   }
@@ -695,6 +690,12 @@ TypePtr parse_type_from_tokens(Lexer& lex) {
   return parse_type_expression(lex);
 }
 
+// for internal usage only
+TypePtr parse_type_from_string(std::string_view text) {
+  Lexer lex(text);
+  return parse_type_expression(lex);
+}
+
 std::ostream& operator<<(std::ostream& os, TypePtr type_data) {
   return os << (type_data ? type_data->as_human_readable() : "(nullptr-type)");
 }

tolk/type-system.h

@@ -417,6 +417,7 @@ public:
 
 class Lexer;
 TypePtr parse_type_from_tokens(Lexer& lex);
+TypePtr parse_type_from_string(std::string_view text);
 
 void type_system_init();