# abseil-duration-subtraction¶

Checks for cases where subtraction should be performed in the absl::Duration domain. When subtracting two values, and the first one is known to be a conversion from absl::Duration, we can infer that the second should also be interpreted as an absl::Duration, and make that inference explicit.

Examples:

// Original - Subtraction in the double domain
double x;
absl::Duration d;
double result = absl::ToDoubleSeconds(d) - x;

// Suggestion - Subtraction in the absl::Duration domain instead
double result = absl::ToDoubleSeconds(d - absl::Seconds(x));

// Original - Subtraction of two Durations in the double domain
absl::Duration d1, d2;
double result = absl::ToDoubleSeconds(d1) - absl::ToDoubleSeconds(d2);

// Suggestion - Subtraction in the absl::Duration domain instead
double result = absl::ToDoubleSeconds(d1 - d2);


Note: As with other clang-tidy checks, it is possible that multiple fixes may overlap (as in the case of nested expressions), so not all occurences can be transformed in one run. In particular, this may occur for nested subtraction expressions. Running clang-tidy multiple times will find and fix these overlaps.