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cppdraft/stmt/ranged.md

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+[stmt.ranged]
+
+# 8 Statements [[stmt]](./#stmt)
+
+## 8.6 Iteration statements [[stmt.iter]](stmt.iter#stmt.ranged)
+
+### 8.6.5 The range-based for statement [stmt.ranged]
+
+[1](#1)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/statements.tex#L703)
+
+The range-based for statement
+
+for ( [*init-statement*](stmt.pre#nt:init-statement "8.1 Preamble [stmt.pre]")opt [*for-range-declaration*](stmt.pre#nt:for-range-declaration "8.1 Preamble [stmt.pre]") : [*for-range-initializer*](stmt.pre#nt:for-range-initializer "8.1 Preamble [stmt.pre]") ) [*statement*](stmt.pre#nt:statement "8.1 Preamble [stmt.pre]")
+
+is equivalent to
+
+{  
+ [*init-statement*](stmt.pre#nt:init-statement "8.1 Preamble [stmt.pre]")opt  
+ auto &&*range* = [*for-range-initializer*](stmt.pre#nt:for-range-initializer "8.1 Preamble [stmt.pre]") ;  
+ auto *begin* = *begin-expr* ;  
+ auto *end* = *end-expr* ;  
+ for ( ; *begin* != *end*; ++*begin* ) {  
+ [*for-range-declaration*](stmt.pre#nt:for-range-declaration "8.1 Preamble [stmt.pre]") = * *begin* ;  
+ [*statement*](stmt.pre#nt:statement "8.1 Preamble [stmt.pre]")  
+ }  
+}
+
+where
+
+- [(1.1)](#1.1)
+
+if the [*for-range-initializer*](stmt.pre#nt:for-range-initializer "8.1 Preamble [stmt.pre]") is an [*expression*](expr.comma#nt:expression "7.6.20 Comma operator [expr.comma]"),
+it is regarded as if it were surrounded by parentheses (so that a comma operator
+cannot be reinterpreted as delimiting two [*init-declarator*](dcl.decl.general#nt:init-declarator "9.3.1 General [dcl.decl.general]")*s*);
+
+- [(1.2)](#1.2)
+
+*range*, *begin*, and *end* are variables defined for
+exposition only; and
+
+- [(1.3)](#1.3)
+
+*begin-expr* and *end-expr* are determined as follows:
+  * [(1.3.1)](#1.3.1)
+
+      if the type of *range* is a reference to an
+array type R, *begin-expr* and *end-expr* are*range* and *range* + N, respectively,
+where N is
+the array bound[.](#1.3.1.sentence-1)
+      If R is an array of unknown bound or an array of
+incomplete type, the program is ill-formed;
+
+  * [(1.3.2)](#1.3.2)
+
+      if the type of *range* is a reference to a
+class type C, and
+searches in the scope of C ([[class.member.lookup]](class.member.lookup "6.5.2 Member name lookup"))
+for the names begin and end each find at least one declaration,*begin-expr* and *end-expr* are*range*.begin() and *range*.end(),
+respectively;
+
+  * [(1.3.3)](#1.3.3)
+
+      otherwise, *begin-expr* and *end-expr* arebegin(*range*) and end(*range*), respectively,
+where begin and end undergo
+argument-dependent lookup ([[basic.lookup.argdep]](basic.lookup.argdep "6.5.4 Argument-dependent name lookup"))[.](#1.3.3.sentence-1)
+      [*Note [1](#note-1)*:
+      Ordinary unqualified lookup ([[basic.lookup.unqual]](basic.lookup.unqual "6.5.3 Unqualified name lookup")) is not
+performed[.](#1.3.3.sentence-2)
+ — *end note*]
+
+[*Example [1](#example-1)*: int array[5] = { 1, 2, 3, 4, 5 };for (int& x : array) x *= 2; — *end example*]
+
+[*Note [2](#note-2)*:
+
+The lifetime of some temporaries in the [*for-range-initializer*](stmt.pre#nt:for-range-initializer "8.1 Preamble [stmt.pre]") is extended to cover the entire loop ([[class.temporary]](class.temporary "6.8.7 Temporary objects"))[.](#1.sentence-2)
+
+— *end note*]
+
+[*Example [2](#example-2)*: using T = std::list<int>;const T& f1(const T& t) { return t; }const T& f2(T t) { return t; } T g();
+
+void foo() {for (auto e : f1(g())) {} // OK, lifetime of return value of g() extendedfor (auto e : f2(g())) {} // undefined behavior} — *end example*]