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Parse child of mispelled await expression as if it was inside async #498

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Parse child of mispelled await expression as if it was inside async #498

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b4f570f
Do not treat `await` followed by arrow function as an identifier
keyehzy Nov 6, 2021
60f52d0
Parse child of mispelled await expression as if was inside async
keyehzy Nov 6, 2021
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42 changes: 35 additions & 7 deletions src/parse.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -701,6 +701,27 @@ expression* parser::parse_async_expression_only(token async_token,
}

expression* parser::parse_await_expression(token await_token, precedence prec) {
bool is_followed_by_arrow = [&]() -> bool {
switch (this->peek().type) {
case token_type::left_paren:
case token_type::identifier: {
buffering_error_reporter temp_error_reporter(&this->temporary_memory_);
error_reporter* old_error_reporter =
std::exchange(this->error_reporter_, &temp_error_reporter);
lexer_transaction transaction = this->lexer_.begin_transaction();

expression* ast = this->parse_expression(prec);

this->lexer_.roll_back_transaction(std::move(transaction));
this->error_reporter_ = old_error_reporter;

return this->is_arrow_kind(ast);
}
default:
return false;
}
}();

bool is_identifier = [&]() -> bool {
if (this->in_async_function_ ||
(this->in_top_level_ &&
Expand Down Expand Up @@ -783,6 +804,9 @@ expression* parser::parse_await_expression(token await_token, precedence prec) {
return is_identifier_result;
}

case token_type::left_paren:
return !this->in_top_level_ && !is_followed_by_arrow;

case token_type::kw_of:
// HACK(strager): This works around for-of parsing. Remove this case
// when for-of parsing is fixed.
Expand All @@ -793,7 +817,6 @@ expression* parser::parse_await_expression(token await_token, precedence prec) {
[[fallthrough]];
case token_type::complete_template:
case token_type::incomplete_template:
case token_type::left_paren:
case token_type::left_square:
case token_type::minus:
case token_type::plus:
Expand Down Expand Up @@ -836,18 +859,23 @@ expression* parser::parse_await_expression(token await_token, precedence prec) {
});
}

expression* child = this->parse_expression(prec);
expression* child;

if (is_followed_by_arrow) {
this->error_reporter_->report(error_await_followed_by_arrow_function{
.await_operator = operator_span,
});
child = this->parse_async_expression(await_token, prec);
} else {
child = this->parse_expression(prec);
}

if (child->kind() == expression_kind::_invalid) {
this->error_reporter_->report(error_missing_operand_for_operator{
.where = operator_span,
});
} else if (this->in_async_function_ && this->is_arrow_kind(child) &&
child->attributes() != function_attributes::async) {
this->error_reporter_->report(error_await_followed_by_arrow_function{
.await_operator = operator_span,
});
}

return this->make_expression<expression::await>(child, operator_span);
}
}
Expand Down
94 changes: 94 additions & 0 deletions test/test-parse-expression.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -961,6 +961,100 @@ TEST_F(test_parse_expression, await_followed_by_arrow_function) {
error_await_followed_by_arrow_function, await_operator,
offsets_matcher(p.code(), 0, u8"await"))));
}

{
test_parser p(u8"await x => {}"_sv);
auto guard = p.parser().enter_function(function_attributes::normal);
expression* ast = p.parse_expression();
EXPECT_EQ(ast->kind(), expression_kind::await);
EXPECT_EQ(ast->child_0()->kind(),
expression_kind::arrow_function_with_statements);
EXPECT_THAT(
p.errors(),
ElementsAre(
ERROR_TYPE_FIELD(error_await_operator_outside_async, await_operator,
offsets_matcher(p.code(), 0, u8"await")),
ERROR_TYPE_FIELD(error_await_followed_by_arrow_function,
await_operator,
offsets_matcher(p.code(), 0, u8"await"))));
}

{
test_parser p(u8"await () => {}"_sv);
auto guard = p.parser().enter_function(function_attributes::normal);
expression* ast = p.parse_expression();
EXPECT_EQ(ast->kind(), expression_kind::await);
EXPECT_EQ(ast->child_0()->kind(),
expression_kind::arrow_function_with_statements);
EXPECT_THAT(
p.errors(),
ElementsAre(
ERROR_TYPE_FIELD(error_await_operator_outside_async, await_operator,
offsets_matcher(p.code(), 0, u8"await")),
ERROR_TYPE_FIELD(error_await_followed_by_arrow_function,
await_operator,
offsets_matcher(p.code(), 0, u8"await"))));
}

{
test_parser p(u8"await () => { await g(); }"_sv);
auto guard = p.parser().enter_function(function_attributes::async);
expression* ast = p.parse_expression();
EXPECT_EQ(ast->kind(), expression_kind::await);
EXPECT_EQ(ast->child_0()->kind(),
expression_kind::arrow_function_with_statements);
EXPECT_THAT(p.errors(),
ElementsAre(ERROR_TYPE_FIELD(
error_await_followed_by_arrow_function, await_operator,
offsets_matcher(p.code(), 0, u8"await"))));
}

{
test_parser p(u8"await x => { await g(); }"_sv);
auto guard = p.parser().enter_function(function_attributes::async);
expression* ast = p.parse_expression();
EXPECT_EQ(ast->kind(), expression_kind::await);
EXPECT_EQ(ast->child_0()->kind(),
expression_kind::arrow_function_with_statements);
EXPECT_THAT(p.errors(),
ElementsAre(ERROR_TYPE_FIELD(
error_await_followed_by_arrow_function, await_operator,
offsets_matcher(p.code(), 0, u8"await"))));
}

{
test_parser p(u8"await () => { await g(); }"_sv);
auto guard = p.parser().enter_function(function_attributes::normal);
expression* ast = p.parse_expression();
EXPECT_EQ(ast->kind(), expression_kind::await);
EXPECT_EQ(ast->child_0()->kind(),
expression_kind::arrow_function_with_statements);
EXPECT_THAT(
p.errors(),
ElementsAre(
ERROR_TYPE_FIELD(error_await_operator_outside_async, await_operator,
offsets_matcher(p.code(), 0, u8"await")),
ERROR_TYPE_FIELD(error_await_followed_by_arrow_function,
await_operator,
offsets_matcher(p.code(), 0, u8"await"))));
}

{
test_parser p(u8"await x => { await g(); }"_sv);
auto guard = p.parser().enter_function(function_attributes::normal);
expression* ast = p.parse_expression();
EXPECT_EQ(ast->kind(), expression_kind::await);
EXPECT_EQ(ast->child_0()->kind(),
expression_kind::arrow_function_with_statements);
EXPECT_THAT(
p.errors(),
ElementsAre(
ERROR_TYPE_FIELD(error_await_operator_outside_async, await_operator,
offsets_matcher(p.code(), 0, u8"await")),
ERROR_TYPE_FIELD(error_await_followed_by_arrow_function,
await_operator,
offsets_matcher(p.code(), 0, u8"await"))));
}
}

TEST_F(test_parse_expression,
Expand Down