# Extra Clang Tools 4 documentation

## clang-tidy - misc-misplaced-widening-cast

# misc-misplaced-widening-cast

This check will warn when there is a cast of a calculation result to a bigger type. If the intention of the cast is to avoid loss of precision then the cast is misplaced, and there can be loss of precision. Otherwise the cast is ineffective.

Example code:

    long f(int x) {
        return (long)(x * 1000);
    }

The result `x * 1000` is first calculated using `int` precision. If the result exceeds `int` precision there is loss of precision. Then the result is casted to `long`.

If there is no loss of precision then the cast can be removed or you can explicitly cast to `int` instead.

If you want to avoid loss of precision then put the cast in a proper location, for instance:

    long f(int x) {
        return (long)x * 1000;
    }

## Implicit casts

Forgetting to place the cast at all is at least as dangerous and at least as common as misplacing it. If `CheckImplicitCasts` is enabled the check also detects these cases, for instance:

    long f(int x) {
        return x * 1000;
    }

## Floating point

Currently warnings are only written for integer conversion. No warning is written for this code:

    double f(float x) {
        return (double)(x * 10.0f);
    }

## Options

`CheckImplicitCasts```

  If non-zero, enables detection of implicit casts. Default is non-zero.