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.. title:: clang-tidy - performance-unnecessary-copy-initialization
performance-unnecessary-copy-initialization
===========================================
Finds local variable declarations that are initialized using the copy
constructor of a non-trivially-copyable type but it would suffice to obtain a
const reference.
The check is only applied if it is safe to replace the copy by a const
reference. This is the case when the variable is const qualified or when it is
only used as a const, i.e. only const methods or operators are invoked on it, or
it is used as const reference or value argument in constructors or function
calls.
Example:
.. code-block:: c++
const string& constReference();
void Function() {
// The warning will suggest making this a const reference.
const string UnnecessaryCopy = constReference();
}
struct Foo {
const string& name() const;
};
void Function(const Foo& foo) {
// The warning will suggest making this a const reference.
string UnnecessaryCopy1 = foo.name();
UnnecessaryCopy1.find("bar");
// The warning will suggest making this a const reference.
string UnnecessaryCopy2 = UnnecessaryCopy1;
UnnecessaryCopy2.find("bar");
}
Options
-------
.. option:: AllowedTypes
A semicolon-separated list of names of types allowed to be initialized by
copying. Regular expressions are accepted, e.g. `[Rr]ef(erence)?$` matches
every type with suffix `Ref`, `ref`, `Reference` and `reference`. The
default is empty.
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