forked from OSchip/llvm-project
37 lines
1.4 KiB
ReStructuredText
37 lines
1.4 KiB
ReStructuredText
.. title:: clang-tidy - abseil-duration-division
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abseil-duration-division
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========================
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``absl::Duration`` arithmetic works like it does with integers. That means that
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division of two ``absl::Duration`` objects returns an ``int64`` with any fractional
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component truncated toward 0. See `this link <https://github.com/abseil/abseil-cpp/blob/29ff6d4860070bf8fcbd39c8805d0c32d56628a3/absl/time/time.h#L137>`_ for more information on arithmetic with ``absl::Duration``.
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For example:
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.. code-block:: c++
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absl::Duration d = absl::Seconds(3.5);
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int64 sec1 = d / absl::Seconds(1); // Truncates toward 0.
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int64 sec2 = absl::ToInt64Seconds(d); // Equivalent to division.
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assert(sec1 == 3 && sec2 == 3);
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double dsec = d / absl::Seconds(1); // WRONG: Still truncates toward 0.
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assert(dsec == 3.0);
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If you want floating-point division, you should use either the
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``absl::FDivDuration()`` function, or one of the unit conversion functions such
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as ``absl::ToDoubleSeconds()``. For example:
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.. code-block:: c++
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absl::Duration d = absl::Seconds(3.5);
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double dsec1 = absl::FDivDuration(d, absl::Seconds(1)); // GOOD: No truncation.
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double dsec2 = absl::ToDoubleSeconds(d); // GOOD: No truncation.
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assert(dsec1 == 3.5 && dsec2 == 3.5);
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This check looks for uses of ``absl::Duration`` division that is done in a
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floating-point context, and recommends the use of a function that returns a
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floating-point value.
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