82 lines
4.9 KiB
Markdown
82 lines
4.9 KiB
Markdown
[support.srcloc.cons]
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# 17 Language support library [[support]](./#support)
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## 17.8 Source location [[support.srcloc]](support.srcloc#cons)
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### 17.8.2 Class source_location [[support.srcloc.class]](support.srcloc.class#support.srcloc.cons)
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#### 17.8.2.2 Creation [support.srcloc.cons]
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[ð](#itemdecl:1)
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`static consteval source_location current() noexcept;
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`
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[1](#1)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L3705)
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*Returns*:
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- [(1.1)](#1.1)
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When invoked by a function call
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whose [*postfix-expression*](expr.post.general#nt:postfix-expression "7.6.1.1 General [expr.post.general]") is
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a (possibly parenthesized) [*id-expression*](expr.prim.id.general#nt:id-expression "7.5.5.1 General [expr.prim.id.general]") naming current,
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returns a source_location with an implementation-defined value[.](#1.1.sentence-1)
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The value should be affected by #line ([[cpp.line]](cpp.line "15.8 Line control"))
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in the same manner as for __LINE__ and __FILE__[.](#1.1.sentence-2)
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The values of the exposition-only data members
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of the returned source_location object
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are indicated in Table [43](#tab:support.srcloc.current "Table 43: Value of object returned by current")[.](#1.1.sentence-3)
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Table [43](#tab:support.srcloc.current) — Value of object returned by current [[tab:support.srcloc.current]](./tab:support.srcloc.current)
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| [ð](#tab:support.srcloc.current-row-1)<br> **Element** | **Value** |
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| --- | --- |
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| [ð](#tab:support.srcloc.current-row-2)<br> line_ | A presumed line number ([[cpp.predefined]](cpp.predefined "15.12 Predefined macro names"))[.](#tab:support.srcloc.current-row-2-column-2-sentence-1)<br>Line numbers are presumed to be 1-indexed; however, an implementation is encouraged to use 0 when the line number is unknown[.](#tab:support.srcloc.current-row-2-column-2-sentence-2) |
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| [ð](#tab:support.srcloc.current-row-3)<br> column_ | An implementation-defined value denoting some offset from the start of the line denoted by line_[.](#tab:support.srcloc.current-row-3-column-2-sentence-1)<br>Column numbers are presumed to be 1-indexed; however, an implementation is encouraged to use 0 when the column number is unknown[.](#tab:support.srcloc.current-row-3-column-2-sentence-2) |
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| [ð](#tab:support.srcloc.current-row-4)<br> file_name_ | A presumed name of the current source file ([[cpp.predefined]](cpp.predefined "15.12 Predefined macro names")) as an ntbs[.](#tab:support.srcloc.current-row-4-column-2-sentence-1) |
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| [ð](#tab:support.srcloc.current-row-5)<br> function_name_ | A name of the current function such as in __func__ ([[dcl.fct.def.general]](dcl.fct.def.general "9.6.1 General")) if any, an empty string otherwise[.](#tab:support.srcloc.current-row-5-column-2-sentence-1) |
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- [(1.2)](#1.2)
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Otherwise, when invoked in some other way, returns a source_location whose data members are initialized
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with valid but unspecified values[.](#1.2.sentence-1)
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[2](#2)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L3748)
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*Remarks*: Any call to current that appears
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as a default member initializer ([[class.mem.general]](class.mem.general "11.4.1 General")), or
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as a subexpression thereof,
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should correspond to the location of
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the constructor definition or aggregate initialization
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that uses the default member initializer[.](#2.sentence-1)
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Any call to current that appears
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as a default argument ([[dcl.fct.default]](dcl.fct.default "9.3.4.7 Default arguments")), or
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as a subexpression thereof,
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should correspond to the location of the invocation of the function
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that uses the default argument ([[expr.call]](expr.call "7.6.1.3 Function call"))[.](#2.sentence-2)
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[3](#3)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L3763)
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[*Example [1](#example-1)*: struct s { source_location member = source_location::current(); int other_member;
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s(source_location loc = source_location::current()): member(loc) // values of member refer to the location of the calling function ([[dcl.fct.default]](dcl.fct.default "9.3.4.7 Default arguments")){} 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();
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f(c); // f's first argument gets the same values as c, above} â *end example*]
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[ð](#itemdecl:2)
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`constexpr source_location() noexcept;
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`
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[4](#4)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L3796)
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*Effects*: The data members are initialized with valid but unspecified values[.](#4.sentence-1)
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