[pulse] A new issue type OPTIONAL_EMPTY_ACCESS for trying to access folly::Optional when it is folly::none
Summary:
We need to check if `folly::Optional` is not `folly::none` if we want to retrieve the value, otherwise a runtime exception is thrown:
```
folly::Optional<int> foo{folly::none};
return foo.value(); // bad
```
```
folly::Optional<int> foo{folly::none};
if (foo) {
return foo.value(); // ok
}
```
This diff adds a new issue type that reports if we try to access `folly::Optional` value when it is known to be `folly::none`.
Reviewed By: ezgicicek
Differential Revision: D22053352
fbshipit-source-id: 32cb00a99
master
Daiva Naudziuniene
5 years ago
committed by
Facebook GitHub Bot
parent
d8a3c4c2a3
commit
2c48e61031
@ -0,0 +1,130 @@
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/*
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* Copyright (c) Facebook, Inc. and its affiliates.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*/
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#include <vector>
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namespace folly {
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template <class Value>
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class Optional;
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struct None {
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enum class _secret { _token };
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explicit constexpr None(_secret) {}
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};
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constexpr None none{None::_secret::_token};
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template <class Value>
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class Optional {
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public:
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typedef Value value_type;
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constexpr Optional();
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Optional(const Optional& src);
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constexpr Optional(const None&) noexcept;
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constexpr Optional(const Value& newValue);
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void assign(const None&);
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void assign(const Optional& src);
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Optional& operator=(None) noexcept {
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reset();
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return *this;
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}
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Optional& operator=(const Optional& other) {
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assign(other);
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return *this;
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}
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template <class... Args>
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Value& emplace(Args&&... args);
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void reset() noexcept;
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constexpr Value& value() &;
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constexpr bool has_value() const noexcept;
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constexpr explicit operator bool() const noexcept { return has_value(); }
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constexpr const Value* operator->() const { return &value(); }
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constexpr Value* operator->() { return &value(); }
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};
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} // namespace folly
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int not_none_ok() {
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folly::Optional<int> foo{5};
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return foo.value();
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}
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int none_check_ok() {
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folly::Optional<int> foo{folly::none};
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if (foo) {
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return foo.value();
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}
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return -1;
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}
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int none_no_check_bad() {
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folly::Optional<int> foo{folly::none};
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return foo.value();
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}
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int none_copy_ok() {
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folly::Optional<int> foo{5};
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folly::Optional<int> bar{foo};
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return bar.value();
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}
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int none_copy_bad() {
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folly::Optional<int> foo{folly::none};
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folly::Optional<int> bar{foo};
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return bar.value();
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}
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int assign_ok() {
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folly::Optional<int> foo{5};
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folly::Optional<int> bar{foo};
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foo = folly::none;
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return bar.value();
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}
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int assign_bad() {
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folly::Optional<int> foo{folly::none};
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folly::Optional<int> bar{5};
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int sum = bar.value();
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bar = foo;
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sum += bar.value();
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return sum;
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}
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int assign2_bad() {
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folly::Optional<int> foo{5};
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int sum = foo.value();
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foo = folly::none;
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sum += foo.value();
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return sum;
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}
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struct State {
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std::vector<int> vec;
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};
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void emplace(folly::Optional<State> state) {
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if (state) {
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state.emplace();
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}
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auto pos = state->vec.begin();
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}
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void operator_arrow_bad() { emplace(folly::none); }
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