From Jason Turner

[support.srcloc.class]

C++17 → C++20 5.0 KB 144 lines
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Archived: C++17 | C++20
Markdown: C++17 | C++20
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tmp/tmp5opvivcd/{from.md → to.md} RENAMED
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+ ### Class `source_location` <a id="support.srcloc.class">[[support.srcloc.class]]</a>
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+
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+ ``` cpp
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+ namespace std {
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+ struct source_location {
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+ // source location construction
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+ static consteval source_location current() noexcept;
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+ constexpr source_location() noexcept;
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+
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+ // source location field access
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+ constexpr uint_least32_t line() const noexcept;
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+ constexpr uint_least32_t column() const noexcept;
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+ constexpr const char* file_name() const noexcept;
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+ constexpr const char* function_name() const noexcept;
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+
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+ private:
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+ uint_least32_t line_; // exposition only
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+ uint_least32_t column_; // exposition only
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+ const char* file_name_; // exposition only
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+ const char* function_name_; // exposition only
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+ };
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+ }
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+ ```
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+
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+ The type `source_location` meets the *Cpp17DefaultConstructible*,
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+ *Cpp17CopyConstructible*, *Cpp17CopyAssignable*, and *Cpp17Destructible*
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+ requirements [[utility.arg.requirements]]. Lvalues of type
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+ `source_location` are swappable [[swappable.requirements]]. All of the
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+ following conditions are `true`:
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+
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+ - `is_nothrow_move_constructible_v<source_location>`
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+ - `is_nothrow_move_assignable_v<source_location>`
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+ - `is_nothrow_swappable_v<source_location>`
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+
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+ [*Note 1*: The intent of `source_location` is to have a small size and
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+ efficient copying. It is unspecified whether the copy/move constructors
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+ and the copy/move assignment operators are trivial and/or
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+ constexpr. — *end note*]
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+
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+ The data members `file_name_` and `function_name_` always each refer to
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+ an NTBS.
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+
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+ The copy/move constructors and the copy/move assignment operators of
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+ `source_location` meet the following postconditions: Given two objects
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+ `lhs` and `rhs` of type `source_location`, where `lhs` is a copy/move
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+ result of `rhs`, and where `rhs_p` is a value denoting the state of
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+ `rhs` before the corresponding copy/move operation, then each of the
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+ following conditions is `true`:
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+
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+ - `strcmp(lhs.file_name(), rhs_p.file_name()) == 0`
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+ - `strcmp(lhs.function_name(), rhs_p.function_name()) == 0`
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+ - `lhs.line() == rhs_p.line()`
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+ - `lhs.column() == rhs_p.column()`
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+
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+ #### Creation <a id="support.srcloc.cons">[[support.srcloc.cons]]</a>
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+
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+ ``` cpp
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+ static consteval source_location current() noexcept;
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+ ```
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+
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+ *Returns:*
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+
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+ - When invoked by a function call whose *postfix-expression* is a
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+ (possibly parenthesized) *id-expression* naming `current`, returns a
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+ `source_location` with an implementation-defined value. The value
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+ should be affected by `#line` [[cpp.line]] in the same manner as for
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+ \_\_LINE\_\_ and \_\_FILE\_\_. The values of the exposition-only data
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+ members of the returned `source_location` object are indicated in
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+ [[support.srcloc.current]].
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+ - Otherwise, when invoked in some other way, returns a `source_location`
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+ whose data members are initialized with valid but unspecified values.
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+
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+ *Remarks:* Any call to `current` that appears as a default member
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+ initializer [[class.mem]], or as a subexpression thereof, should
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+ correspond to the location of the constructor definition or aggregate
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+ initialization that uses the default member initializer. Any call to
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+ `current` that appears as a default argument [[dcl.fct.default]], or as
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+ a subexpression thereof, should correspond to the location of the
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+ invocation of the function that uses the default argument [[expr.call]].
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+
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+ [*Example 1*:
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+
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+ ``` cpp
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+ struct s {
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+ source_location member = source_location::current();
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+ int other_member;
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+ s(source_location loc = source_location::current())
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+ : member(loc) // values of member refer to the location of the calling function[dcl.fct.default]
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+ {}
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+ s(int blather) : // values of member refer to this location
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+ other_member(blather)
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+ {}
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+ s(double) // values of member refer to this location
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+ {}
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+ };
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+ void f(source_location a = source_location::current()) {
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+ source_location b = source_location::current(); // values in b refer to this line
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+ }
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+
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+ void g() {
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+ f(); // f's first argument corresponds to this line of code
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+
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+ source_location c = source_location::current();
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+ f(c); // f's first argument gets the same values as c, above
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+ }
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+ ```
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+
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+ — *end example*]
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+
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+ ``` cpp
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+ constexpr source_location() noexcept;
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+ ```
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+
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+ The data members are initialized with valid but unspecified values.
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+
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+ #### Observers <a id="support.srcloc.obs">[[support.srcloc.obs]]</a>
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+
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+ ``` cpp
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+ constexpr uint_least32_t line() const noexcept;
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+ ```
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+
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+ *Returns:* `line_`.
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+
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+ ``` cpp
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+ constexpr uint_least32_t column() const noexcept;
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+ ```
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+
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+ *Returns:* `column_`.
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+
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+ ``` cpp
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+ constexpr const char* file_name() const noexcept;
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+ ```
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+
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+ *Returns:* `file_name_`.
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+
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+ ``` cpp
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+ constexpr const char* function_name() const noexcept;
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+ ```
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+
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+ *Returns:* `function_name_`.
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+