[PATCH v1] treewide: Remove top-level `const` from return types

Stefan Klug stefan.klug at ideasonboard.com
Tue Jun 3 14:36:13 CEST 2025


Hi Barnabás,

Thank you for the patch.

Quoting Barnabás Pőcze (2025-06-03 13:14:34)
> Top-level `const` qualifiers are not useful, so avoid them. This is done
> either by simply removing the top-level `const`, or making the function
> return a reference to const where that is appropriate.
> 
> Signed-off-by: Barnabás Pőcze <barnabas.pocze at ideasonboard.com>

Do we need to note somewhere that this breaks the ABI?

Reviewed-by: Stefan Klug <stefan.klug at ideasonboard.com>

Best regards,
Stefan

> ---
>  include/libcamera/base/log.h                  | 2 +-
>  include/libcamera/geometry.h                  | 6 +++---
>  include/libcamera/internal/matrix.h           | 2 +-
>  include/libcamera/internal/v4l2_subdevice.h   | 2 +-
>  include/libcamera/internal/v4l2_videodevice.h | 2 +-
>  src/apps/cam/drm.h                            | 4 ++--
>  src/ipa/libipa/histogram.h                    | 2 +-
>  src/libcamera/geometry.cpp                    | 6 +++---
>  src/libcamera/pipeline/ipu3/ipu3.cpp          | 2 +-
>  src/libcamera/pipeline/mali-c55/mali-c55.cpp  | 8 ++++----
>  src/libcamera/v4l2_subdevice.cpp              | 2 +-
>  src/libcamera/v4l2_videodevice.cpp            | 2 +-
>  12 files changed, 20 insertions(+), 20 deletions(-)
> 
> diff --git a/include/libcamera/base/log.h b/include/libcamera/base/log.h
> index 8af74b59d..5a232a650 100644
> --- a/include/libcamera/base/log.h
> +++ b/include/libcamera/base/log.h
> @@ -75,7 +75,7 @@ public:
>         const LogCategory &category() const { return category_; }
>         const std::string &fileInfo() const { return fileInfo_; }
>         const std::string &prefix() const { return prefix_; }
> -       const std::string msg() const { return msgStream_.str(); }
> +       std::string msg() const { return msgStream_.str(); }
>  
>  private:
>         LIBCAMERA_DISABLE_COPY_AND_MOVE(LogMessage)
> diff --git a/include/libcamera/geometry.h b/include/libcamera/geometry.h
> index f322e3d5b..d9378efec 100644
> --- a/include/libcamera/geometry.h
> +++ b/include/libcamera/geometry.h
> @@ -31,7 +31,7 @@ public:
>         int x;
>         int y;
>  
> -       const std::string toString() const;
> +       std::string toString() const;
>  
>         constexpr Point operator-() const
>         {
> @@ -64,7 +64,7 @@ public:
>         unsigned int height;
>  
>         bool isNull() const { return !width && !height; }
> -       const std::string toString() const;
> +       std::string toString() const;
>  
>         Size &alignDownTo(unsigned int hAlignment, unsigned int vAlignment)
>         {
> @@ -275,7 +275,7 @@ public:
>         unsigned int height;
>  
>         bool isNull() const { return !width && !height; }
> -       const std::string toString() const;
> +       std::string toString() const;
>  
>         Point center() const;
>  
> diff --git a/include/libcamera/internal/matrix.h b/include/libcamera/internal/matrix.h
> index 47513b995..1842389f2 100644
> --- a/include/libcamera/internal/matrix.h
> +++ b/include/libcamera/internal/matrix.h
> @@ -56,7 +56,7 @@ public:
>  
>         ~Matrix() = default;
>  
> -       const std::string toString() const
> +       std::string toString() const
>         {
>                 std::stringstream out;
>  
> diff --git a/include/libcamera/internal/v4l2_subdevice.h b/include/libcamera/internal/v4l2_subdevice.h
> index fa2a4a21e..c1cde1df2 100644
> --- a/include/libcamera/internal/v4l2_subdevice.h
> +++ b/include/libcamera/internal/v4l2_subdevice.h
> @@ -66,7 +66,7 @@ struct V4L2SubdeviceFormat {
>         Size size;
>         std::optional<ColorSpace> colorSpace;
>  
> -       const std::string toString() const;
> +       std::string toString() const;
>  };
>  
>  std::ostream &operator<<(std::ostream &out, const V4L2SubdeviceFormat &f);
> diff --git a/include/libcamera/internal/v4l2_videodevice.h b/include/libcamera/internal/v4l2_videodevice.h
> index ae6a76cb0..6caafc4dc 100644
> --- a/include/libcamera/internal/v4l2_videodevice.h
> +++ b/include/libcamera/internal/v4l2_videodevice.h
> @@ -178,7 +178,7 @@ public:
>         std::array<Plane, 3> planes;
>         unsigned int planesCount = 0;
>  
> -       const std::string toString() const;
> +       std::string toString() const;
>  };
>  
>  std::ostream &operator<<(std::ostream &out, const V4L2DeviceFormat &f);
> diff --git a/src/apps/cam/drm.h b/src/apps/cam/drm.h
> index 1ba83b6eb..30a916d7e 100644
> --- a/src/apps/cam/drm.h
> +++ b/src/apps/cam/drm.h
> @@ -97,9 +97,9 @@ public:
>  
>         bool isImmutable() const { return flags_ & DRM_MODE_PROP_IMMUTABLE; }
>  
> -       const std::vector<uint64_t> values() const { return values_; }
> +       const std::vector<uint64_t> &values() const { return values_; }
>         const std::map<uint32_t, std::string> &enums() const { return enums_; }
> -       const std::vector<uint32_t> blobs() const { return blobs_; }
> +       const std::vector<uint32_t> &blobs() const { return blobs_; }
>  
>  private:
>         Type type_;
> diff --git a/src/ipa/libipa/histogram.h b/src/ipa/libipa/histogram.h
> index a926002c8..8cf8bb6d1 100644
> --- a/src/ipa/libipa/histogram.h
> +++ b/src/ipa/libipa/histogram.h
> @@ -36,7 +36,7 @@ public:
>         }
>  
>         size_t bins() const { return cumulative_.size() - 1; }
> -       const Span<const uint64_t> data() const { return cumulative_; }
> +       Span<const uint64_t> data() const { return cumulative_; }
>         uint64_t total() const { return cumulative_[cumulative_.size() - 1]; }
>         uint64_t cumulativeFrequency(double bin) const;
>         double quantile(double q, uint32_t first = 0, uint32_t last = UINT_MAX) const;
> diff --git a/src/libcamera/geometry.cpp b/src/libcamera/geometry.cpp
> index 81cc8cd53..de76d0c12 100644
> --- a/src/libcamera/geometry.cpp
> +++ b/src/libcamera/geometry.cpp
> @@ -53,7 +53,7 @@ namespace libcamera {
>   * \brief Assemble and return a string describing the point
>   * \return A string describing the point
>   */
> -const std::string Point::toString() const
> +std::string Point::toString() const
>  {
>         std::stringstream ss;
>         ss << *this;
> @@ -133,7 +133,7 @@ std::ostream &operator<<(std::ostream &out, const Point &p)
>   * \brief Assemble and return a string describing the size
>   * \return A string describing the size
>   */
> -const std::string Size::toString() const
> +std::string Size::toString() const
>  {
>         std::stringstream ss;
>         ss << *this;
> @@ -676,7 +676,7 @@ std::ostream &operator<<(std::ostream &out, const SizeRange &sr)
>   * \brief Assemble and return a string describing the rectangle
>   * \return A string describing the Rectangle
>   */
> -const std::string Rectangle::toString() const
> +std::string Rectangle::toString() const
>  {
>         std::stringstream ss;
>         ss << *this;
> diff --git a/src/libcamera/pipeline/ipu3/ipu3.cpp b/src/libcamera/pipeline/ipu3/ipu3.cpp
> index e31e3879d..ad20810e6 100644
> --- a/src/libcamera/pipeline/ipu3/ipu3.cpp
> +++ b/src/libcamera/pipeline/ipu3/ipu3.cpp
> @@ -105,7 +105,7 @@ public:
>         Status validate() override;
>  
>         const StreamConfiguration &cio2Format() const { return cio2Configuration_; }
> -       const ImgUDevice::PipeConfig imguConfig() const { return pipeConfig_; }
> +       const ImgUDevice::PipeConfig &imguConfig() const { return pipeConfig_; }
>  
>         /* Cache the combinedTransform_ that will be applied to the sensor */
>         Transform combinedTransform_;
> diff --git a/src/libcamera/pipeline/mali-c55/mali-c55.cpp b/src/libcamera/pipeline/mali-c55/mali-c55.cpp
> index 4acc091bd..28d5da3c8 100644
> --- a/src/libcamera/pipeline/mali-c55/mali-c55.cpp
> +++ b/src/libcamera/pipeline/mali-c55/mali-c55.cpp
> @@ -101,8 +101,8 @@ public:
>         int loadIPA();
>  
>         /* Deflect these functionalities to either TPG or CameraSensor. */
> -       const std::vector<Size> sizes(unsigned int mbusCode) const;
> -       const Size resolution() const;
> +       std::vector<Size> sizes(unsigned int mbusCode) const;
> +       Size resolution() const;
>  
>         int pixfmtToMbusCode(const PixelFormat &pixFmt) const;
>         const PixelFormat &bestRawFormat() const;
> @@ -195,7 +195,7 @@ void MaliC55CameraData::setSensorControls(const ControlList &sensorControls)
>         delayedCtrls_->push(sensorControls);
>  }
>  
> -const std::vector<Size> MaliC55CameraData::sizes(unsigned int mbusCode) const
> +std::vector<Size> MaliC55CameraData::sizes(unsigned int mbusCode) const
>  {
>         if (sensor_)
>                 return sensor_->sizes(mbusCode);
> @@ -218,7 +218,7 @@ const std::vector<Size> MaliC55CameraData::sizes(unsigned int mbusCode) const
>         return sizes;
>  }
>  
> -const Size MaliC55CameraData::resolution() const
> +Size MaliC55CameraData::resolution() const
>  {
>         if (sensor_)
>                 return sensor_->resolution();
> diff --git a/src/libcamera/v4l2_subdevice.cpp b/src/libcamera/v4l2_subdevice.cpp
> index 33279654d..e9c849ac5 100644
> --- a/src/libcamera/v4l2_subdevice.cpp
> +++ b/src/libcamera/v4l2_subdevice.cpp
> @@ -923,7 +923,7 @@ const MediaBusFormatInfo &MediaBusFormatInfo::info(uint32_t code)
>   * \brief Assemble and return a string describing the format
>   * \return A string describing the V4L2SubdeviceFormat
>   */
> -const std::string V4L2SubdeviceFormat::toString() const
> +std::string V4L2SubdeviceFormat::toString() const
>  {
>         std::stringstream ss;
>         ss << *this;
> diff --git a/src/libcamera/v4l2_videodevice.cpp b/src/libcamera/v4l2_videodevice.cpp
> index d53aa2d3c..58a6704ef 100644
> --- a/src/libcamera/v4l2_videodevice.cpp
> +++ b/src/libcamera/v4l2_videodevice.cpp
> @@ -429,7 +429,7 @@ bool V4L2BufferCache::Entry::operator==(const FrameBuffer &buffer) const
>   * \brief Assemble and return a string describing the format
>   * \return A string describing the V4L2DeviceFormat
>   */
> -const std::string V4L2DeviceFormat::toString() const
> +std::string V4L2DeviceFormat::toString() const
>  {
>         std::stringstream ss;
>         ss << *this;
> -- 
> 2.49.0
>


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