[clang-tidy] Add the abseil-duration-factory-float check

Summary:
This check finds cases where calls to an absl::Duration factory could use the more efficient integer overload.

For example:
// Original - Providing a floating-point literal.
absl::Duration d = absl::Seconds(10.0);

// Suggested - Use an integer instead.
absl::Duration d = absl::Seconds(10);

Patch by hwright.

Reviewers: alexfh, hokein, aaron.ballman, JonasToth

Reviewed By: hokein, JonasToth

Subscribers: zturner, xazax.hun, Eugene.Zelenko, mgorny, cfe-commits

Tags: #clang-tools-extra

Differential Revision: https://reviews.llvm.org/D53339

3 files changed, 37 insertions, 0 deletions

diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index 7b70216b81d..4b1a6f2b7c8 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -74,6 +74,13 @@ Improvements to clang-tidy
   floating-point context, and recommends the use of a function that
   returns a floating-point value.
 
+- New :doc:`abseil-duration-factory-float
+  <clang-tidy/checks/abseil-duration-factory-float>` check.
+
+  Checks for cases where the floating-point overloads of various
+  ``absl::Duration`` factory functions are called when the more-efficient
+  integer versions could be used instead.
+
 - 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-float.rst b/clang-tools-extra/docs/clang-tidy/checks/abseil-duration-factory-float.rst
new file mode 100644
index 00000000000..a4fc6d4291d
--- /dev/null
+++ b/clang-tools-extra/docs/clang-tidy/checks/abseil-duration-factory-float.rst
@@ -0,0 +1,29 @@
+.. title:: clang-tidy - abseil-duration-factory-float
+
+abseil-duration-factory-float
+=============================
+
+Checks for cases where the floating-point overloads of various
+``absl::Duration`` factory functions are called when the more-efficient
+integer versions could be used instead.
+
+This check will not suggest fixes for literals which contain fractional
+floating point values or non-literals. It will suggest removing
+superfluous casts.
+
+Examples:
+
+.. code-block:: c++
+
+  // Original - Providing a floating-point literal.
+  absl::Duration d = absl::Seconds(10.0);
+
+  // Suggested - Use an integer instead.
+  absl::Duration d = absl::Seconds(10);
+
+
+  // Original - Explicitly casting to a floating-point type.
+  absl::Duration d = absl::Seconds(static_cast<double>(10));
+
+  // Suggested - Remove the explicit cast
+  absl::Duration d = absl::Seconds(10);
diff --git a/clang-tools-extra/docs/clang-tidy/checks/list.rst b/clang-tools-extra/docs/clang-tidy/checks/list.rst
index f7fa7c5a33f..a5b5a4f7780 100644
--- a/clang-tools-extra/docs/clang-tidy/checks/list.rst
+++ b/clang-tools-extra/docs/clang-tidy/checks/list.rst
@@ -5,6 +5,7 @@ Clang-Tidy Checks
 
 .. toctree::
    abseil-duration-division
+   abseil-duration-factory-float
    abseil-faster-strsplit-delimiter
    abseil-no-internal-dependencies
    abseil-no-namespace