public:

// Severity of the RuntimeIssue.

//

// Can be used to determine whether to continue program planning or return

// early.

enum class Severity {

// The issue may lead to runtime errors in evaluation.

kWarning = 0,

// The expression is invalid or unsupported.

kError = 1,

// Arbitrary max value above Error.

kNotForUseWithExhaustiveSwitchStatements = 15

};

// Code for well-known runtime error kinds.

enum class ErrorCode {

// Overload not provided for given function call signature.

kNoMatchingOverload,

// Field access refers to unknown field for given type.

kNoSuchField,

// Other error outside the canonical set.

kOther,

};

static RuntimeIssue CreateError(absl::Status status,

ErrorCode error_code = ErrorCode::kOther) {

return RuntimeIssue(std::move(status), Severity::kError, error_code);

}

static RuntimeIssue CreateWarning(absl::Status status,

ErrorCode error_code = ErrorCode::kOther) {

return RuntimeIssue(std::move(status), Severity::kWarning, error_code);

}

RuntimeIssue(const RuntimeIssue& other) = default;

RuntimeIssue& operator=(const RuntimeIssue& other) = default;

RuntimeIssue(RuntimeIssue&& other) = default;

RuntimeIssue& operator=(RuntimeIssue&& other) = default;

Severity severity() const { return severity_; }

ErrorCode error_code() const { return error_code_; }

const absl::Status& ToStatus() const& { return status_; }

absl::Status ToStatus() && { return std::move(status_); }

private:

RuntimeIssue(absl::Status status, Severity severity, ErrorCode error_code)

: status_(std::move(status)),

error_code_(error_code),

severity_(severity) {}

absl::Status status_;

ErrorCode error_code_;

Severity severity_;