可以使用C ++ 11的'auto'恶化性能，甚至破坏代码？

问题描述

此问题与现有问题

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Such a deferred conversion may break the code when auto is combined with lazy evaluation (real world example 1, example 2):

class Matrix { ... };

class MatrixExpression {
    ...
    operator Matrix() const;
};

MatrixExpression operator+(const Matrix& a, const Matrix& b);
std::ostream& operator(std::ostream& out, const Matrix& m);

Matrix a = ...;
Matrix b = ...;
auto c = a + b; // evaluation of the matrix addition doesn't happen here
a[0][0] += 1;
std::cout << c; // matrix addition is evaluated here, using the new state of 'a'

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