@@ -92,8 +92,8 @@ public:
return *this;
}
- constexpr Size alignedDownTo(unsigned int hAlignment,
- unsigned int vAlignment) const
+ [[nodiscard]] constexpr Size alignedDownTo(unsigned int hAlignment,
+ unsigned int vAlignment) const
{
return {
width / hAlignment * hAlignment,
@@ -101,8 +101,8 @@ public:
};
}
- constexpr Size alignedUpTo(unsigned int hAlignment,
- unsigned int vAlignment) const
+ [[nodiscard]] constexpr Size alignedUpTo(unsigned int hAlignment,
+ unsigned int vAlignment) const
{
return {
(width + hAlignment - 1) / hAlignment * hAlignment,
@@ -110,7 +110,7 @@ public:
};
}
- constexpr Size boundedTo(const Size &bound) const
+ [[nodiscard]] constexpr Size boundedTo(const Size &bound) const
{
return {
std::min(width, bound.width),
@@ -118,7 +118,7 @@ public:
};
}
- constexpr Size expandedTo(const Size &expand) const
+ [[nodiscard]] constexpr Size expandedTo(const Size &expand) const
{
return {
std::max(width, expand.width),
@@ -126,10 +126,10 @@ public:
};
}
- Size boundedToAspectRatio(const Size &ratio) const;
- Size expandedToAspectRatio(const Size &ratio) const;
+ [[nodiscard]] Size boundedToAspectRatio(const Size &ratio) const;
+ [[nodiscard]] Size expandedToAspectRatio(const Size &ratio) const;
- Rectangle centeredTo(const Point ¢er) const;
+ [[nodiscard]] Rectangle centeredTo(const Point ¢er) const;
Size operator*(float factor) const;
Size operator/(float factor) const;
@@ -247,10 +247,11 @@ public:
Rectangle &scaleBy(const Size &numerator, const Size &denominator);
Rectangle &translateBy(const Point &point);
- Rectangle boundedTo(const Rectangle &bound) const;
- Rectangle enclosedIn(const Rectangle &boundary) const;
- Rectangle scaledBy(const Size &numerator, const Size &denominator) const;
- Rectangle translatedBy(const Point &point) const;
+ [[nodiscard]] Rectangle boundedTo(const Rectangle &bound) const;
+ [[nodiscard]] Rectangle enclosedIn(const Rectangle &boundary) const;
+ [[nodiscard]] Rectangle scaledBy(const Size &numerator,
+ const Size &denominator) const;
+ [[nodiscard]] Rectangle translatedBy(const Point &point) const;
};
bool operator==(const Rectangle &lhs, const Rectangle &rhs);
Geometry classes generally have two sets of functions, one that operates on the object and modifies it (e.g. Rectangle::scaleBy()), and one that performs the same operations by instead return a modified copy of the object, leaving the original untouched (e.g.Rectangle::scaledBy()). As the names are close, they can easily be mistaken, with the const version used instead of the in-place version. To catch these errors at compile time, mark the const versions with [[nodiscard]], as there is no use case for calling them without using the result of the call. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> --- include/libcamera/geometry.h | 27 ++++++++++++++------------- 1 file changed, 14 insertions(+), 13 deletions(-) This patch came as a result of catching one of the issues described in the commit message during review of another patch. [[nodiscard]] is only available in C++17, which would make it impossible to use libcamera in C++14 code (this can for instance for a problem with Chromium - the web browser, not the OS). An alternative would be to define a custom attribute, for instance #define __nodiscard [[nodiscard]] in a public header (compile.h ? util.h ?), conditionally on the C++ version. The check would thus be disabled in application compiled with C++14, but would be enabled for the compilation of libcamera itself. Is this worth it ?