I'm compiling some of Serenity's code with clang 11.1.0 and it reported some issues which may warrant fixing.

../.././AK/BitmapView.h:75:29: error: cast from 'const u8 *' (aka 'const unsigned char *') to 'const u32 *' (aka 'const unsigned int *') increases required alignment from 1 to 4 [-Werror,-Wcast-align]
                    ptr32 = (const u32*)last;
                            ^~~~~~~~~~~~~~~~
../.././AK/BitmapView.h:214:25: error: cast from 'u8 *' (aka 'unsigned char *') to 'u32 *' (aka 'unsigned int *') increases required alignment from 1 to 4 [-Werror,-Wcast-align]
        u32* bitmap32 = (u32*)m_data;
                        ^~~~~~~~~~~~

../../Userland/Libraries/LibGfx/Path.cpp:21:23: error: implicit conversion increases floating-point precision: 'float' to 'double' [-Werror,-Wdouble-promotion]
    double rx = radii.x();
           ~~   ~~~~~~^~~
../../Userland/Libraries/LibGfx/Path.cpp:22:23: error: implicit conversion increases floating-point precision: 'float' to 'double' [-Werror,-Wdouble-promotion]
    double ry = radii.y();
           ~~   ~~~~~~^~~
../../Userland/Libraries/LibGfx/Path.cpp:91:47: error: implicit conversion increases floating-point precision: 'float' to 'double' [-Werror,-Wdouble-promotion]
    x_avg = (last_point.x() + next_point.x()) / 2.0f;
          ~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~
../../Userland/Libraries/LibGfx/Path.cpp:92:47: error: implicit conversion increases floating-point precision: 'float' to 'double' [-Werror,-Wdouble-promotion]
    y_avg = (last_point.y() + next_point.y()) / 2.0f;
          ~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~

../../Userland/Libraries/LibGfx/Rect.cpp:78:45: error: member reference base type 'Line' is not a structure or union
    return Line { center(), other.center() }.length();
           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~
../../Userland/Libraries/LibGfx/Rect.cpp:100:41: error: member reference base type 'Line' is not a structure or union
    return Line { points[0], points[0] }.length();
           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~
../../Userland/Libraries/LibGfx/Rect.cpp:169:54: error: member reference base type 'Line' is not a structure or union
        auto distance = Line { point_on_line, point }.length();
                        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~