Difference between revisions of "cpp/named req/TriviallyCopyable"
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This implies that a trivially copyable class has no [[cpp/language/virtual|virtual functions]] or [[cpp/language/derived_class#Virtual_base_classes|virtual base classes]]. | This implies that a trivially copyable class has no [[cpp/language/virtual|virtual functions]] or [[cpp/language/derived_class#Virtual_base_classes|virtual base classes]]. | ||
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| + | ===Notes=== | ||
| + | Until C++20, a copy constructor, move constructor, copy assignment operator, or move assignment operator is eligible if and only if it is non-deleted. | ||
===Defect reports=== | ===Defect reports=== | ||
Revision as of 22:09, 15 August 2020
Contents |
Requirements
The following types are collectively called trivially copyable types:
- Scalar types
- Trivially copyable classes, i.e. classes satisfying following requirements:
- At least one copy constructor, move constructor, copy assignment operator, or move assignment operator is eligible
- Every eligible copy constructor (if any) is trivial
- Every eligible move constructor (if any) is trivial
- Every eligible copy assignment operator (if any) is trivial
- Every eligible move assignment operator (if any) is trivial
- Has a trivial non-deleted destructor
- Arrays of TriviallyCopyable objects
This implies that a trivially copyable class has no virtual functions or virtual base classes.
Notes
Until C++20, a copy constructor, move constructor, copy assignment operator, or move assignment operator is eligible if and only if it is non-deleted.
Defect reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
| DR | Applied to | Behavior as published | Correct behavior |
|---|---|---|---|
| CWG 1734 | C++11 | C++03 POD with deleted non-trivial assignment was not trivial | deleted ctors/operators allowed |
| CWG 2094 | C++11 | Volatile scalar types are not trivially copyable (CWG 1746) | made trivially copyable |
See also
| (C++11) |
checks if a type is trivially copyable (class template) |
