Implement static class initializer blocks (#144)

Spec compliance bug: "await" is illegal inside initializer blocks
_except_ when used as an identifier in a function expression, like so:

    class C {
        static {
            var f = function await() {}
        }
    }

It is somewhat complicated to make the parser understand the distinction
and such code is probably rare or non-existent so I decided to leave
well enough alone for now.

quickjs.c

@@ -17820,6 +17820,7 @@ typedef enum JSParseFunctionEnum {
     JS_PARSE_FUNC_GETTER,
     JS_PARSE_FUNC_SETTER,
     JS_PARSE_FUNC_METHOD,
+    JS_PARSE_FUNC_CLASS_STATIC_INIT,
     JS_PARSE_FUNC_CLASS_CONSTRUCTOR,
     JS_PARSE_FUNC_DERIVED_CLASS_CONSTRUCTOR,
 } JSParseFunctionEnum;
@@ -18688,7 +18689,13 @@ static __exception int next_token(JSParseState *s)
         s->token.u.ident.atom = atom;
         s->token.u.ident.has_escape = ident_has_escape;
         s->token.u.ident.is_reserved = FALSE;
-        if (s->token.u.ident.atom <= JS_ATOM_LAST_KEYWORD ||
+        // TODO(bnoordhuis) accept await when used in a function expression
+        // inside the static initializer block
+        if (s->cur_func->func_type == JS_PARSE_FUNC_CLASS_STATIC_INIT &&
+            (atom == JS_ATOM_arguments || atom == JS_ATOM_await)) {
+            s->token.u.ident.is_reserved = TRUE;
+            s->token.val = TOK_IDENT;
+        } else if (s->token.u.ident.atom <= JS_ATOM_LAST_KEYWORD ||
             (s->token.u.ident.atom <= JS_ATOM_LAST_STRICT_KEYWORD &&
              (s->cur_func->js_mode & JS_MODE_STRICT)) ||
             (s->token.u.ident.atom == JS_ATOM_yield &&
@@ -20836,6 +20843,44 @@ static __exception int js_parse_class(JSParseState *s, BOOL is_class_expr,
         if (is_static) {
             if (next_token(s))
                 goto fail;
+            if (s->token.val == '{') {
+                ClassFieldsDef *cf = &class_fields[is_static];
+                if (!cf->fields_init_fd)
+                    if (emit_class_init_start(s, cf))
+                        goto fail;
+                s->cur_func = cf->fields_init_fd;
+                // stack is now: <empty>
+                JSFunctionDef *init;
+                if (js_parse_function_decl2(s, JS_PARSE_FUNC_CLASS_STATIC_INIT,
+                                            JS_FUNC_NORMAL, JS_ATOM_NULL,
+                                            s->token.ptr, s->token.line_num,
+                                            JS_PARSE_EXPORT_NONE, &init) < 0) {
+                    goto fail;
+                }
+                // stack is now: fclosure
+                push_scope(s);
+                emit_op(s, OP_scope_get_var);
+                emit_atom(s, JS_ATOM_this);
+                emit_u16(s, 0);
+                // stack is now: fclosure this
+                if (class_name != JS_ATOM_NULL) {
+                    // TODO(bnoordhuis) pass as argument to init method?
+                    emit_op(s, OP_dup);
+                    emit_op(s, OP_scope_put_var_init);
+                    emit_atom(s, class_name);
+                    emit_u16(s, s->cur_func->scope_level);
+                }
+                emit_op(s, OP_swap);
+                // stack is now: this fclosure
+                emit_op(s, OP_call_method);
+                emit_u16(s, 0);
+                // stack is now: returnvalue
+                emit_op(s, OP_drop);
+                // stack is now: <empty>
+                pop_scope(s);
+                s->cur_func = s->cur_func->parent;
+                continue;
+            }
             /* allow "static" field name */
             if (s->token.val == ';' || s->token.val == '=') {
                 is_static = FALSE;
@@ -24085,6 +24130,10 @@ static __exception int js_parse_statement_or_decl(JSParseState *s,
             js_parse_error(s, "return not in a function");
             goto fail;
         }
+        if (s->cur_func->func_type == JS_PARSE_FUNC_CLASS_STATIC_INIT) {
+            js_parse_error(s, "return in a static initializer block");
+            goto fail;
+        }
         if (next_token(s))
             goto fail;
         if (s->token.val != ';' && s->token.val != '}' && !s->got_lf) {
@@ -30646,7 +30695,9 @@ static __exception int js_parse_function_decl2(JSParseState *s,
                  (func_kind & JS_FUNC_GENERATOR)) ||
                 (s->token.u.ident.atom == JS_ATOM_await &&
                  func_type == JS_PARSE_FUNC_EXPR &&
-                 (func_kind & JS_FUNC_ASYNC))) {
+                 (func_kind & JS_FUNC_ASYNC)) ||
+                (s->token.u.ident.atom == JS_ATOM_await &&
+                 func_type == JS_PARSE_FUNC_CLASS_STATIC_INIT)) {
                 return js_parse_error_reserved_identifier(s);
             }
         }
@@ -30740,7 +30791,8 @@ static __exception int js_parse_function_decl2(JSParseState *s,
                            func_type == JS_PARSE_FUNC_SETTER ||
                            func_type == JS_PARSE_FUNC_CLASS_CONSTRUCTOR ||
                            func_type == JS_PARSE_FUNC_DERIVED_CLASS_CONSTRUCTOR);
-    fd->has_arguments_binding = (func_type != JS_PARSE_FUNC_ARROW);
+    fd->has_arguments_binding = (func_type != JS_PARSE_FUNC_ARROW &&
+                                 func_type != JS_PARSE_FUNC_CLASS_STATIC_INIT);
     fd->has_this_binding = fd->has_arguments_binding;
     fd->is_derived_class_constructor = (func_type == JS_PARSE_FUNC_DERIVED_CLASS_CONSTRUCTOR);
     if (func_type == JS_PARSE_FUNC_ARROW) {
@@ -30748,6 +30800,11 @@ static __exception int js_parse_function_decl2(JSParseState *s,
         fd->super_call_allowed = fd->parent->super_call_allowed;
         fd->super_allowed = fd->parent->super_allowed;
         fd->arguments_allowed = fd->parent->arguments_allowed;
+    } else if (func_type == JS_PARSE_FUNC_CLASS_STATIC_INIT) {
+        fd->new_target_allowed = TRUE; // although new.target === undefined
+        fd->super_call_allowed = FALSE;
+        fd->super_allowed = TRUE;
+        fd->arguments_allowed = FALSE;
     } else {
         fd->new_target_allowed = TRUE;
         fd->super_call_allowed = fd->is_derived_class_constructor;
@@ -30785,7 +30842,7 @@ static __exception int js_parse_function_decl2(JSParseState *s,
         if (add_arg(ctx, fd, name) < 0)
             goto fail;
         fd->defined_arg_count = 1;
-    } else {
+    } else if (func_type != JS_PARSE_FUNC_CLASS_STATIC_INIT) {
         if (s->token.val == '(') {
             int skip_bits;
             /* if there is an '=' inside the parameter list, we
@@ -31005,8 +31062,10 @@ static __exception int js_parse_function_decl2(JSParseState *s,
         }
     }
 
-    if (js_parse_expect(s, '{'))
+    // js_parse_class() already consumed the '{'
-        goto fail;
+    if (func_type != JS_PARSE_FUNC_CLASS_STATIC_INIT)
+        if (js_parse_expect(s, '{'))
+            goto fail;
 
     if (js_parse_directives(s))
         goto fail;

test262.conf

@@ -79,7 +79,7 @@ class-fields-private
 class-fields-private-in=skip
 class-fields-public
 class-methods-private
-class-static-block=skip
+class-static-block
 class-static-fields-private
 class-static-fields-public
 class-static-methods-private

test262_errors.txt

@@ -92,6 +92,8 @@ test262/test/built-ins/TypedArrayConstructors/internals/Set/key-is-out-of-bounds
 test262/test/built-ins/TypedArrayConstructors/internals/Set/key-is-out-of-bounds.js:22: strict mode: Test262Error: Reflect.set(sample, "-1", 1) must return true Expected SameValue(«false», «true») to be true (Testing with Float64Array.)
 test262/test/built-ins/TypedArrayConstructors/internals/Set/tonumber-value-detached-buffer.js:39: Test262Error: Expected SameValue(«false», «true») to be true (Testing with Float64Array.)
 test262/test/built-ins/TypedArrayConstructors/internals/Set/tonumber-value-detached-buffer.js:39: strict mode: Test262Error: Expected SameValue(«false», «true») to be true (Testing with Float64Array.)
+test262/test/language/expressions/arrow-function/static-init-await-reference.js:12: unexpected error type: Test262: This statement should not be evaluated.
+test262/test/language/expressions/arrow-function/static-init-await-reference.js:12: strict mode: unexpected error type: Test262: This statement should not be evaluated.
 test262/test/language/expressions/assignment/target-member-computed-reference-null.js:32: Test262Error: Expected a DummyError but got a TypeError
 test262/test/language/expressions/assignment/target-member-computed-reference-null.js:32: strict mode: Test262Error: Expected a DummyError but got a TypeError
 test262/test/language/expressions/assignment/target-member-computed-reference-undefined.js:32: Test262Error: Expected a DummyError but got a TypeError
@@ -124,6 +126,10 @@ test262/test/language/expressions/delete/super-property-null-base.js:26: Test262
 test262/test/language/expressions/delete/super-property-null-base.js:26: strict mode: Test262Error: Expected a ReferenceError but got a TypeError
 test262/test/language/expressions/dynamic-import/usage-from-eval.js:26: TypeError: $DONE() not called
 test262/test/language/expressions/dynamic-import/usage-from-eval.js:26: strict mode: TypeError: $DONE() not called
+test262/test/language/expressions/function/static-init-await-binding.js:16: SyntaxError: 'await' is a reserved identifier
+test262/test/language/expressions/function/static-init-await-binding.js:16: strict mode: SyntaxError: 'await' is a reserved identifier
+test262/test/language/expressions/generators/static-init-await-binding.js:16: SyntaxError: 'await' is a reserved identifier
+test262/test/language/expressions/generators/static-init-await-binding.js:16: strict mode: SyntaxError: 'await' is a reserved identifier
 test262/test/language/expressions/logical-assignment/left-hand-side-private-reference-accessor-property-and.js:60: Test262Error: The expression should evaluate to the result Expected SameValue(«undefined», «false») to be true
 test262/test/language/expressions/logical-assignment/left-hand-side-private-reference-accessor-property-and.js:60: strict mode: Test262Error: The expression should evaluate to the result Expected SameValue(«undefined», «false») to be true
 test262/test/language/expressions/logical-assignment/left-hand-side-private-reference-accessor-property-nullish.js:59: Test262Error: The expression should evaluate to the result Expected SameValue(«undefined», «1») to be true