Init

cppdraft/conv/ptr.md

@@ -0,0 +1,73 @@
+[conv.ptr]
+
+# 7 Expressions [[expr]](./#expr)
+
+## 7.3 Standard conversions [[conv]](conv#ptr)
+
+### 7.3.12 Pointer conversions [conv.ptr]
+
+[1](#1)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/expressions.tex#L1022)
+
+A [*null pointer constant*](#def:constant,null_pointer "7.3.12 Pointer conversions [conv.ptr]") is an integer literal ([[lex.icon]](lex.icon "5.13.2 Integer literals")) with
+value zero
+or a prvalue of type std​::​nullptr_t[.](#1.sentence-1)
+
+A null pointer constant can be
+converted to a pointer type; the
+result is the null pointer value of that type ([[basic.compound]](basic.compound "6.9.4 Compound types")) and is
+distinguishable from every other value of
+object pointer or function pointer
+type[.](#1.sentence-2)
+
+Such a conversion is called a [*null pointer conversion*](#def:conversion,null_pointer "7.3.12 Pointer conversions [conv.ptr]")[.](#1.sentence-3)
+
+The conversion of a null pointer constant to a pointer to
+cv-qualified type is a single conversion, and not the sequence of a
+pointer conversion followed by a qualification
+conversion ([[conv.qual]](conv.qual "7.3.6 Qualification conversions"))[.](#1.sentence-4)
+
+A null pointer constant of integral type
+can be converted to a prvalue of type std​::​nullptr_t[.](#1.sentence-5)
+
+[*Note [1](#note-1)*:
+
+The resulting prvalue is not a null pointer value[.](#1.sentence-6)
+
+— *end note*]
+
+[2](#2)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/expressions.tex#L1045)
+
+A prvalue of type “pointer to cv T”, where T is an object type, can be converted to a prvalue of type “pointer tocv void”[.](#2.sentence-1)
+
+The pointer value ([[basic.compound]](basic.compound "6.9.4 Compound types")) is unchanged by this conversion[.](#2.sentence-2)
+
+[3](#3)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/expressions.tex#L1051)
+
+A prvalue v of type “pointer to cv D”, where D is a complete class type, can be converted to a prvalue of type “pointer tocv B”, where B is a base class ([[class.derived]](class.derived "11.7 Derived classes"))
+of D[.](#3.sentence-1)
+
+If B is an
+inaccessible ([[class.access]](class.access "11.8 Member access control")) or
+ambiguous ([[class.member.lookup]](class.member.lookup "6.5.2 Member name lookup")) base class of D, a program
+that necessitates this conversion is ill-formed[.](#3.sentence-2)
+
+If v is a null pointer value,
+the result is a null pointer value[.](#3.sentence-3)
+
+Otherwise,
+if B is a virtual base class of D andv does not point to an object
+whose type is similar ([[conv.qual]](conv.qual "7.3.6 Qualification conversions")) to D and
+that is
+within its lifetime or
+within its period of construction or destruction ([[class.cdtor]](class.cdtor "11.9.5 Construction and destruction")),
+the behavior is undefined[.](#3.sentence-4)
+
+Otherwise,
+the result is a pointer to the base class subobject of
+the derived class object[.](#3.sentence-5)