[basic.lookup.elab]

# 6 Basics [[basic]](./#basic)

## 6.5 Name lookup [[basic.lookup]](basic.lookup#elab)

### 6.5.6 Elaborated type specifiers [basic.lookup.elab]

[1](#1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/basic.tex#L2745)

If the [*class-key*](class.pre#nt:class-key "11.1 Preamble [class.pre]") or enum keyword
in an [*elaborated-type-specifier*](dcl.type.elab#nt:elaborated-type-specifier "9.2.9.5 Elaborated type specifiers [dcl.type.elab]") is followed by an [*identifier*](lex.name#nt:identifier "5.11 Identifiers [lex.name]") that is not followed by ​::​,
lookup for the [*identifier*](lex.name#nt:identifier "5.11 Identifiers [lex.name]") is type-only ([[basic.lookup.general]](basic.lookup.general "6.5.1 General"))[.](#1.sentence-1)

[*Note [1](#note-1)*:

In general, the recognition of an [*elaborated-type-specifier*](dcl.type.elab#nt:elaborated-type-specifier "9.2.9.5 Elaborated type specifiers [dcl.type.elab]") depends on the following tokens[.](#1.sentence-2)

If the [*identifier*](lex.name#nt:identifier "5.11 Identifiers [lex.name]") is followed by ​::​,
see [[basic.lookup.qual]](basic.lookup.qual "6.5.5 Qualified name lookup")[.](#1.sentence-3)

— *end note*]

[2](#2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/basic.tex#L2758)

If the terminal name of the [*elaborated-type-specifier*](dcl.type.elab#nt:elaborated-type-specifier "9.2.9.5 Elaborated type specifiers [dcl.type.elab]") is a qualified name,
lookup for it is type-only[.](#2.sentence-1)

If the name lookup does not find a previously declared [*type-name*](dcl.type.simple#nt:type-name "9.2.9.3 Simple type specifiers [dcl.type.simple]"),
the [*elaborated-type-specifier*](dcl.type.elab#nt:elaborated-type-specifier "9.2.9.5 Elaborated type specifiers [dcl.type.elab]") is ill-formed[.](#2.sentence-2)

[3](#3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/basic.tex#L2765)

[*Example [1](#example-1)*: struct Node {struct Node* Next; // OK, refers to injected-class-name Nodestruct Data* Data; // OK, declares type Data at global scope and member Data};

struct Data {struct Node* Node; // OK, refers to Node at global scopefriend struct ::Glob; // error: Glob is not declared, cannot introduce a qualified type ([[dcl.type.elab]](dcl.type.elab "9.2.9.5 Elaborated type specifiers"))friend struct Glob; // OK, refers to (as yet) undeclared Glob at global scope./* ... */};

struct Base {struct Data; // OK, declares nested Datastruct ::Data* thatData; // OK, refers to ​::​Datastruct Base::Data* thisData; // OK, refers to nested Datafriend class ::Data; // OK, global Data is a friendfriend class Data; // OK, nested Data is a friendstruct Data { /* ... */ }; // Defines nested Data};

struct Data; // OK, redeclares Data at global scopestruct ::Data; // error: cannot introduce a qualified type ([[dcl.type.elab]](dcl.type.elab "9.2.9.5 Elaborated type specifiers"))struct Base::Data; // error: cannot introduce a qualified type ([[dcl.type.elab]](dcl.type.elab "9.2.9.5 Elaborated type specifiers"))struct Base::Datum; // error: Datum undefinedstruct Base::Data* pBase; // OK, refers to nested Data — *end example*]