cppdraft_translate/cppdraft/support/srcloc/cons.md

[support.srcloc.cons]

17 Language support library [support]

17.8 Source location [support.srcloc]

17.8.2 Class source_location [support.srcloc.class]

17.8.2.2 Creation [support.srcloc.cons]

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static consteval source_location current() noexcept;

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Returns:

• (1.1)

  When invoked by a function call whose postfix-expression is a (possibly parenthesized) id-expression naming current, returns a source_location with an implementation-defined value. The value should be affected by #line ([cpp.line]) in the same manner as for LINE and FILE. The values of the exposition-only data members of the returned source_location object are indicated in Table 43. Table 43 — Value of object returned by current [tab:support.srcloc.current]

🔗 Element	Value
🔗 line_	A presumed line number ([cpp.predefined]). Line numbers are presumed to be 1-indexed; however, an implementation is encouraged to use 0 when the line number is unknown.
🔗 column_	An implementation-defined value denoting some offset from the start of the line denoted by line_. Column numbers are presumed to be 1-indexed; however, an implementation is encouraged to use 0 when the column number is unknown.
🔗 file_name_	A presumed name of the current source file ([cpp.predefined]) as an ntbs.
🔗 function_name_	A name of the current function such as in func ([dcl.fct.def.general]) if any, an empty string otherwise.

• (1.2)

  Otherwise, when invoked in some other way, returns a source_location whose data members are initialized with valid but unspecified values.

2

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Remarks: Any call to current that appears as a default member initializer ([class.mem.general]), or as a subexpression thereof, should correspond to the location of the constructor definition or aggregate initialization that uses the default member initializer.

Any call to current that appears as a default argument ([dcl.fct.default]), or as a subexpression thereof, should correspond to the location of the invocation of the function that uses the default argument ([expr.call]).

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[Example 1: struct s { source_location member = source_location::current(); int other_member; s(source_location loc = source_location::current()): member(loc) // values of member refer to the location of the calling function ([dcl.fct.default]){} s(int blather) : // values of member refer to this location other_member(blather){} s(double) // values of member refer to this location{}};void f(source_location a = source_location::current()) { source_location b = source_location::current(); // values in b refer to this line}void g() { f(); // f's first argument corresponds to this line of code source_location c = source_location::current(); f(c); // f's first argument gets the same values as c, above} — end example]

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constexpr source_location() noexcept;

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Effects: The data members are initialized with valid but unspecified values.