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:

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");
}

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