Merge "Fix OkOrFail<status_t> conversion ambiguities" (5a1f51b0) · Commits · e / os / android_system_core

libutils/Errors_test.cpp

+62 −0

Original line number	Diff line number	Diff line
		@@ -108,3 +108,65 @@ TEST(errors, result_in_status) {
		status_t b = g(false);
		EXPECT_EQ(PERMISSION_DENIED, b);
		}

		TEST(errors, conversion_promotion) {
		constexpr size_t successVal = 10ull;
		auto f = [&](bool success) -> Result<size_t, StatusT> {
		OR_RETURN(success_or_fail(success));
		return successVal;
		};
		auto s = f(true);
		ASSERT_TRUE(s.ok());
		EXPECT_EQ(s.value(), successVal);
		auto r = f(false);
		EXPECT_TRUE(!r.ok());
		EXPECT_EQ(PERMISSION_DENIED, r.error().code());
		}

		TEST(errors, conversion_promotion_bool) {
		constexpr size_t successVal = true;
		auto f = [&](bool success) -> Result<bool, StatusT> {
		OR_RETURN(success_or_fail(success));
		return successVal;
		};
		auto s = f(true);
		ASSERT_TRUE(s.ok());
		EXPECT_EQ(s.value(), successVal);
		auto r = f(false);
		EXPECT_TRUE(!r.ok());
		EXPECT_EQ(PERMISSION_DENIED, r.error().code());
		}

		TEST(errors, conversion_promotion_char) {
		constexpr char successVal = 'a';
		auto f = [&](bool success) -> Result<unsigned char, StatusT> {
		OR_RETURN(success_or_fail(success));
		return successVal;
		};
		auto s = f(true);
		ASSERT_TRUE(s.ok());
		EXPECT_EQ(s.value(), successVal);
		auto r = f(false);
		EXPECT_TRUE(!r.ok());
		EXPECT_EQ(PERMISSION_DENIED, r.error().code());
		}

		struct IntContainer {
		// Implicit conversion from int is desired
		IntContainer(int val) : val_(val) {}
		int val_;
		};

		TEST(errors, conversion_construct) {
		constexpr int successVal = 10;
		auto f = [&](bool success) -> Result<IntContainer, StatusT> {
		OR_RETURN(success_or_fail(success));
		return successVal;
		};
		auto s = f(true);
		ASSERT_TRUE(s.ok());
		EXPECT_EQ(s.value().val_, successVal);
		auto r = f(false);
		EXPECT_TRUE(!r.ok());
		EXPECT_EQ(PERMISSION_DENIED, r.error().code());
		}

libutils/include/utils/ErrorsMacros.h

+104 −4

Original line number	Diff line number	Diff line
		@@ -25,6 +25,7 @@
		// [1] build/soong/cc/config/global.go#commonGlobalIncludes
		#include <android-base/errors.h>
		#include <android-base/result.h>
		#include <log/log_main.h>

		#include <assert.h>

		@@ -44,13 +45,58 @@ struct StatusT {
		status_t val_;
		};


		namespace base {
		// TODO(b/221235365) StatusT fulfill ResultError contract and cleanup.

		// Unlike typical ResultError types, the underlying code should be a status_t
		// instead of a StatusT. We also special-case message generation.
		template<>
		struct ResultError<StatusT, false> {
		ResultError(status_t s) : val_(s) {
		LOG_FATAL_IF(s == OK, "Result error should not hold success");
		}

		template <typename T>
		operator expected<T, ResultError<StatusT, false>>() const {
		return unexpected(*this);
		}

		std::string message() const { return statusToString(val_); }
		status_t code() const { return val_; }

		private:
		const status_t val_;
		};

		template<>
		struct ResultError<StatusT, true> {
		template <typename T>
		ResultError(T&& message, status_t s) : val_(s), message_(std::forward<T>(message)) {
		LOG_FATAL_IF(s == OK, "Result error should not hold success");
		}

		ResultError(status_t s) : val_(s) {}

		template <typename T>
		operator expected<T, ResultError<StatusT, true>>() const {
		return unexpected(*this);
		}

		status_t code() const { return val_; }

		std::string message() const { return statusToString(val_) + message_; }
		private:
		const status_t val_;
		std::string message_;
		};

		// Specialization of android::base::OkOrFail<V> for V = status_t. This is used to use the OR_RETURN
		// and OR_FATAL macros with statements that yields a value of status_t. See android-base/errors.h
		// for the detailed contract.
		template <>
		struct OkOrFail<status_t> {
		static_assert(std::is_same_v<status_t, int>);
		// Tests if status_t is a success value of not.
		static bool IsOk(const status_t& s) { return s == OK; }

		@@ -71,16 +117,70 @@ struct OkOrFail<status_t> {

		// Or converts into Result<T, StatusT>. This is used when OR_RETURN is used in a function whose
		// return type is Result<T, StatusT>.
		template <typename T, typename = std::enable_if_t<!std::is_same_v<T, status_t>>>

		template <typename T>
		operator Result<T, StatusT>() && {
		return Error<StatusT>(std::move(val_));
		return ResultError<StatusT>(std::move(val_));
		}

		operator Result<int, StatusT>() && { return Error<StatusT>(std::move(val_)); }
		template<typename T>
		operator Result<T, StatusT, false>() && {
		return ResultError<StatusT, false>(std::move(val_));
		}

		// Since user defined conversion can be followed by numeric conversion,
		// we have to specialize all conversions to results holding numeric types to
		// avoid conversion ambiguities with the constructor of expected.
		#pragma push_macro("SPECIALIZED_CONVERSION")
		#define SPECIALIZED_CONVERSION(type)\
		operator Result<type, StatusT>() && { return ResultError<StatusT>(std::move(val_)); }\
		operator Result<type, StatusT, false>() && { return ResultError<StatusT, false>(std::move(val_));}

		SPECIALIZED_CONVERSION(int)
		SPECIALIZED_CONVERSION(short int)
		SPECIALIZED_CONVERSION(unsigned short int)
		SPECIALIZED_CONVERSION(unsigned int)
		SPECIALIZED_CONVERSION(long int)
		SPECIALIZED_CONVERSION(unsigned long int)
		SPECIALIZED_CONVERSION(long long int)
		SPECIALIZED_CONVERSION(unsigned long long int)
		SPECIALIZED_CONVERSION(bool)
		SPECIALIZED_CONVERSION(char)
		SPECIALIZED_CONVERSION(unsigned char)
		SPECIALIZED_CONVERSION(signed char)
		SPECIALIZED_CONVERSION(wchar_t)
		SPECIALIZED_CONVERSION(char16_t)
		SPECIALIZED_CONVERSION(char32_t)
		SPECIALIZED_CONVERSION(float)
		SPECIALIZED_CONVERSION(double)
		SPECIALIZED_CONVERSION(long double)
		#undef SPECIALIZED_CONVERSION
		#pragma pop_macro("SPECIALIZED_CONVERSION")
		// String representation of the error value.
		static std::string ErrorMessage(const status_t& s) { return statusToString(s); }
		};

		} // namespace base


		// These conversions make StatusT directly comparable to status_t in order to
		// avoid calling code whenever comparisons are desired.

		template <bool include_message>
		bool operator==(const base::ResultError<StatusT, include_message>& l, const status_t& r) {
		return (l.code() == r);
		}
		template <bool include_message>
		bool operator==(const status_t& l, const base::ResultError<StatusT, include_message>& r) {
		return (l == r.code());
		}

		template <bool include_message>
		bool operator!=(const base::ResultError<StatusT, include_message>& l, const status_t& r) {
		return (l.code() != r);
		}
		template <bool include_message>
		bool operator!=(const status_t& l, const base::ResultError<StatusT, include_message>& r) {
		return (l != r.code());
		}

		} // namespace android