From Jason Turner

[meta.reflection.exception]

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tmp/tmpwcy6lqe5/{from.md → to.md} RENAMED
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+ ### Class `exception` <a id="meta.reflection.exception">[[meta.reflection.exception]]</a>
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+
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+ ``` cpp
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+ namespace std::meta {
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+ class exception : public std::exception {
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+ private:
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+ optional<string> what_; // exposition only
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+ u8string u8what_; // exposition only
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+ info from_; // exposition only
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+ source_location where_; // exposition only
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+
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+ public:
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+ consteval exception(u8string_view what, info from,
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+ source_location where = source_location::current()) noexcept;
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+
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+ consteval exception(string_view what, info from,
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+ source_location where = source_location::current()) noexcept;
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+
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+ exception(const exception&) = default;
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+ exception(exception&&) = default;
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+
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+ exception& operator=(const exception&) = default;
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+ exception& operator=(exception&&) = default;
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+
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+ constexpr const char* what() const noexcept override;
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+ consteval u8string_view u8what() const noexcept;
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+ consteval info from() const noexcept;
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+ consteval source_location where() const noexcept;
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+ };
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+ }
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+ ```
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+
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+ Reflection functions throw exceptions of type `meta::exception` to
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+ signal an error. `meta::exception` is a consteval-only type.
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+
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+ ``` cpp
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+ consteval exception(u8string_view what, info from,
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+ source_location where = source_location::current()) noexcept;
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+ ```
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+
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+ *Effects:* Initializes *u8what\_* with `what`, *from\_* with `from`, and
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+ *where\_* with `where`. If `what` can be represented in the ordinary
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+ literal encoding, initializes *what\_* with `what`, transcoded from
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+ UTF-8 to the ordinary literal encoding. Otherwise, *what\_* is
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+ value-initialized.
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+
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+ ``` cpp
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+ consteval exception(string_view what, info from,
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+ source_location where = source_location::current()) noexcept;
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+ ```
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+
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+ `what` designates a sequence of characters that can be encoded in UTF-8.
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+
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+ *Effects:* Initializes *what\_* with `what`, *u8what\_* with `what`
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+ transcoded from the ordinary literal encoding to UTF-8, *from\_* with
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+ `from` and *where\_* with `where`.
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+
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+ ``` cpp
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+ constexpr const char* what() const noexcept override;
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+ ```
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+
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+ *`what_`*`.has_value()` is `true`.
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+
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+ *Returns:* *`what_`*`->c_str()`.
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+
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+ ``` cpp
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+ consteval u8string_view u8what() const noexcept;
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+ ```
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+
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+ *Returns:* *u8what\_*.
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+
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+ ``` cpp
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+ consteval info from() const noexcept;
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+ ```
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+
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+ *Returns:* *from\_*.
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+
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+ ``` cpp
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+ consteval source_location where() const noexcept;
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+ ```
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+
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+ *Returns:* *where\_*.
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+