Add the abseil-duration-factory-scale check.

This check removes unneeded scaling of arguments when calling Abseil Time factory functions.

Patch by Hyrum Wright.

3 files changed, 42 insertions, 0 deletions

diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index 1d49c81aba9..2773e235462 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -81,6 +81,12 @@ Improvements to clang-tidy
   ``absl::Duration`` factory functions are called when the more-efficient
   integer versions could be used instead.
 
+- New :doc:`abseil-duration-factory-scale
+  <clang-tidy/checks/abseil-duration-factory-scale>` check.
+
+  Checks for cases where arguments to ``absl::Duration`` factory functions are
+  scaled internally and could be changed to a different factory function.
+
 - New :doc:`abseil-faster-strsplit-delimiter
   <clang-tidy/checks/abseil-faster-strsplit-delimiter>` check.
 
diff --git a/clang-tools-extra/docs/clang-tidy/checks/abseil-duration-factory-scale.rst b/clang-tools-extra/docs/clang-tidy/checks/abseil-duration-factory-scale.rst
new file mode 100644
index 00000000000..8b99d4685f3
--- /dev/null
+++ b/clang-tools-extra/docs/clang-tidy/checks/abseil-duration-factory-scale.rst
@@ -0,0 +1,35 @@
+.. title:: clang-tidy - abseil-duration-factory-scale
+
+abseil-duration-factory-scale
+=============================
+
+Checks for cases where arguments to ``absl::Duration`` factory functions are
+scaled internally and could be changed to a different factory function. This
+check also looks for arguements with a zero value and suggests using
+``absl::ZeroDuration()`` instead.
+
+Examples:
+
+.. code-block:: c++
+
+  // Original - Internal multiplication.
+  int x;
+  absl::Duration d = absl::Seconds(60 * x);
+
+  // Suggested - Use absl::Minutes instead.
+  absl::Duration d = absl::Minutes(x);
+
+
+  // Original - Internal division.
+  int y;
+  absl::Duration d = absl::Milliseconds(y / 1000.);
+
+  // Suggested - Use absl:::Seconds instead.
+  absl::Duration d = absl::Seconds(y);
+
+
+  // Original - Zero-value argument.
+  absl::Duration d = absl::Hours(0);
+
+  // Suggested = Use absl::ZeroDuration instead
+  absl::Duration d = absl::ZeroDuration();
diff --git a/clang-tools-extra/docs/clang-tidy/checks/list.rst b/clang-tools-extra/docs/clang-tidy/checks/list.rst
index f33af36ed58..7fa19471895 100644
--- a/clang-tools-extra/docs/clang-tidy/checks/list.rst
+++ b/clang-tools-extra/docs/clang-tidy/checks/list.rst
@@ -6,6 +6,7 @@ Clang-Tidy Checks
 .. toctree::
    abseil-duration-division
    abseil-duration-factory-float
+   abseil-duration-factory-scale
    abseil-faster-strsplit-delimiter
    abseil-no-internal-dependencies
    abseil-no-namespace