2019-02-28 04:08:50 +08:00
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.. title:: clang-tidy - abseil-time-subtraction
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abseil-time-subtraction
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=======================
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Finds and fixes ``absl::Time`` subtraction expressions to do subtraction
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in the Time domain instead of the numeric domain.
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There are two cases of Time subtraction in which deduce additional type
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information:
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2019-02-28 23:01:17 +08:00
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- When the result is an ``absl::Duration`` and the first argument is an
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``absl::Time``.
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- When the second argument is a ``absl::Time``.
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2019-02-28 04:08:50 +08:00
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In the first case, we must know the result of the operation, since without that
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the second operand could be either an ``absl::Time`` or an ``absl::Duration``.
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In the second case, the first operand *must* be an ``absl::Time``, because
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subtracting an ``absl::Time`` from an ``absl::Duration`` is not defined.
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Examples:
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.. code-block:: c++
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2019-02-28 23:39:47 +08:00
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2019-02-28 04:08:50 +08:00
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int x;
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absl::Time t;
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// Original - absl::Duration result and first operand is a absl::Time.
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absl::Duration d = absl::Seconds(absl::ToUnixSeconds(t) - x);
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// Suggestion - Perform subtraction in the Time domain instead.
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absl::Duration d = t - absl::FromUnixSeconds(x);
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// Original - Second operand is an absl::Time.
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int i = x - absl::ToUnixSeconds(t);
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// Suggestion - Perform subtraction in the Time domain instead.
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int i = absl::ToInt64Seconds(absl::FromUnixSeconds(x) - t);
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