2016-01-29 23:21:32 +08:00
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performance-implicit-cast-in-loop
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=================================
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2016-04-01 07:09:42 +08:00
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This warning appears in a range-based loop with a loop variable of const ref
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type where the type of the variable does not match the one returned by the
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iterator.
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2016-01-29 23:21:32 +08:00
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This means that an implicit cast has been added, which can for example result in
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expensive deep copies.
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Example:
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.. code:: c++
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map<int, vector<string>> my_map;
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for (const pair<int, vector<string>>& p : my_map) {}
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// The iterator type is in fact pair<const int, vector<string>>, which means
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// that the compiler added a cast, resulting in a copy of the vectors.
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The easiest solution is usually to use "const auto&" instead of writing the type
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manually.
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