AK+Userland: Add generic `AK::abs()` function and use it

Previously, in LibGFX's `Point` class, calculated distances were passed
to the integer `abs` function, even if the stored type was a float. This
caused the value to unexpectedly be truncated. Luckily, this API was not
used with floating point types, but that can change in the future, so
why not fix it now :^)

Since we are in C++, we can use function overloading to make things
easy, and to automatically use the right version.

This is even better than the LibC/LibM functions, as using a bit of
hackery, they are able to be constant-evaluated. They use compiler
intrinsics, so they do not depend on external code and the compiler can
emit the most optimized code by default.

Since we aren't using the C++ standard library's trick of importing
everything into the `AK` namespace, this `abs` function cannot be
exported to the global namespace, as the names would clash.

4 files changed, 9 insertions, 9 deletions

diff --git a/Userland/Demos/Eyes/EyesWidget.cpp b/Userland/Demos/Eyes/EyesWidget.cpp
index 2fe07ba04d..87eb099787 100644
--- a/Userland/Demos/Eyes/EyesWidget.cpp
+++ b/Userland/Demos/Eyes/EyesWidget.cpp
@@ -5,6 +5,7 @@
  */
 
 #include "EyesWidget.h"
+#include <AK/StdLibExtraDetails.h>
 #include <LibGUI/Painter.h>
 #include <LibGUI/Window.h>
 #include <LibGUI/WindowServerConnection.h>
@@ -89,14 +90,14 @@ Gfx::IntPoint EyesWidget::pupil_center(Gfx::IntRect& eyeball_bounds) const
     double max_distance_along_this_direction;
 
     // clang-format off
-    if (dx != 0 && abs(dx) >= abs(dy)) {
+    if (dx != 0 && AK::abs(dx) >= AK::abs(dy)) {
         double slope = dy / dx;
         double slope_squared = slope * slope;
         max_distance_along_this_direction = 0.25 * sqrt(
             (slope_squared + 1) /
             (1 / width_squared + slope_squared / height_squared)
         );
-    } else if (dy != 0 && abs(dy) >= abs(dx)) {
+    } else if (dy != 0 && AK::abs(dy) >= AK::abs(dx)) {
         double slope = dx / dy;
         double slope_squared = slope * slope;
         max_distance_along_this_direction = 0.25 * sqrt(
diff --git a/Userland/Libraries/LibGfx/Point.h b/Userland/Libraries/LibGfx/Point.h
index c5a3c54be4..1d1f8f2df9 100644
--- a/Userland/Libraries/LibGfx/Point.h
+++ b/Userland/Libraries/LibGfx/Point.h
@@ -13,7 +13,6 @@
 #include <LibGfx/Orientation.h>
 #include <LibIPC/Forward.h>
 #include <math.h>
-#include <stdlib.h>
 
 namespace Gfx {
 
@@ -217,7 +216,7 @@ public:
     // Returns pixels moved from other in either direction
     [[nodiscard]] T pixels_moved(Point<T> const& other) const
     {
-        return max(abs(dx_relative_to(other)), abs(dy_relative_to(other)));
+        return max(AK::abs(dx_relative_to(other)), AK::abs(dy_relative_to(other)));
     }
 
     [[nodiscard]] float distance_from(Point<T> const& other) const
@@ -229,7 +228,7 @@ public:
 
     [[nodiscard]] Point absolute_relative_distance_to(Point const& other) const
     {
-        return { abs(dx_relative_to(other)), abs(dy_relative_to(other)) };
+        return { AK::abs(dx_relative_to(other)), AK::abs(dy_relative_to(other)) };
     }
 
     template<typename U>
diff --git a/Userland/Libraries/LibJS/Runtime/Value.cpp b/Userland/Libraries/LibJS/Runtime/Value.cpp
index c60a7f8157..5666b28e71 100644
--- a/Userland/Libraries/LibJS/Runtime/Value.cpp
+++ b/Userland/Libraries/LibJS/Runtime/Value.cpp
@@ -179,7 +179,7 @@ static String double_to_string(double d)
         else
             builder.append('-');
 
-        builder.append(String::number(fabs(exponent - 1)));
+        builder.append(String::number(AK::abs(exponent - 1)));
         return builder.to_string();
     }
 
@@ -193,7 +193,7 @@ static String double_to_string(double d)
     else
         builder.append('-');
 
-    builder.append(String::number(fabs(exponent - 1)));
+    builder.append(String::number(AK::abs(exponent - 1)));
     return builder.to_string();
 }
 
diff --git a/Userland/Libraries/LibWeb/Layout/FlexFormattingContext.cpp b/Userland/Libraries/LibWeb/Layout/FlexFormattingContext.cpp
index 9887bbf469..1c9cb5d431 100644
--- a/Userland/Libraries/LibWeb/Layout/FlexFormattingContext.cpp
+++ b/Userland/Libraries/LibWeb/Layout/FlexFormattingContext.cpp
@@ -482,7 +482,7 @@ void FlexFormattingContext::run(Box& box, LayoutMode)
 
             if (sum_of_unfrozen_flex_items_flex_factors < 1) {
                 auto intermediate_free_space = initial_free_space * sum_of_unfrozen_flex_items_flex_factors;
-                if (abs(intermediate_free_space) < abs(remaining_free_space))
+                if (AK::abs(intermediate_free_space) < AK::abs(remaining_free_space))
                     remaining_free_space = intermediate_free_space;
             }
 
@@ -503,7 +503,7 @@ void FlexFormattingContext::run(Box& box, LayoutMode)
 
                     for_each_unfrozen_item([&](FlexItem* flex_item) {
                         float ratio = flex_item->scaled_flex_shrink_factor / sum_of_scaled_flex_shrink_factor_of_unfrozen_items;
-                        flex_item->target_main_size = flex_item->flex_base_size - (abs(remaining_free_space) * ratio);
+                        flex_item->target_main_size = flex_item->flex_base_size - (AK::abs(remaining_free_space) * ratio);
                     });
                 }
             } else {