Replace til::some with til::small_vector (microsoft#16952)

`til::small_vector` had a bug: Its internal backing buffer didn't
prevent default initialization! Wrapping it in an `union` fixed that.

`til::some` had the same issue, but thinking about it I realized we
don't need both classes to exist, so I removed `til::some` since
`til::small_vector` is more flexible.

Checking the assembly, I noticed that `til::small_vector` with the
`union` fix produced a more compact result. I also noticed that in
combination with function calls and inlining the bit-wise ANDs in
the point/size/rect boolean operators produced poor-ish results.
Since their impact on performance is negligible to begin with I
simplified that code slightly.

Finally, I noticed that the boolean operator for `til::point`
was incorrect since it checked for `>0` instead of `>=0`.
Luckily nothing seemed to have used that operator yet.
(= No inbox regression.)

src/inc/til/point.h

@@ -58,7 +58,7 @@ namespace til // Terminal Implementation Library. Also: "Today I Learned"
 
         constexpr explicit operator bool() const noexcept
         {
-            return (x > 0) & (y > 0);
+            return x >= 0 && y >= 0;
         }
 
         constexpr bool operator<(const point other) const noexcept

src/inc/til/rect.h

@@ -4,11 +4,11 @@
 #pragma once
 
 #include "bit.h"
-#include "some.h"
 #include "math.h"
 #include "size.h"
 #include "point.h"
 #include "operators.h"
+#include "small_vector.h"
 
 namespace til // Terminal Implementation Library. Also: "Today I Learned"
 {
@@ -31,8 +31,7 @@ namespace til // Terminal Implementation Library. Also: "Today I Learned"
 
         explicit constexpr operator bool() const noexcept
         {
-            return (left >= 0) & (top >= 0) &
-                   (right >= left) & (bottom >= top);
+            return left >= 0 && top >= 0 && right >= left && bottom >= top;
         }
     };
 
@@ -204,8 +203,7 @@ namespace til // Terminal Implementation Library. Also: "Today I Learned"
 
         explicit constexpr operator bool() const noexcept
         {
-            return (left >= 0) & (top >= 0) &
-                   (right > left) & (bottom > top);
+            return left >= 0 && top >= 0 && right > left && bottom > top;
         }
 
         constexpr const_iterator begin() const
@@ -294,9 +292,9 @@ namespace til // Terminal Implementation Library. Also: "Today I Learned"
         }
 
         // - = subtract
-        constexpr some<rect, 4> operator-(const rect& other) const
+        small_vector<rect, 4> operator-(const rect& other) const
         {
-            some<rect, 4> result;
+            small_vector<rect, 4> result;
 
             // We could have up to four rectangles describing the area resulting when you take removeMe out of main.
             // Find the intersection of the two so we know which bits of removeMe are actually applicable
@@ -566,14 +564,12 @@ namespace til // Terminal Implementation Library. Also: "Today I Learned"
 
         constexpr bool contains(point pt) const noexcept
         {
-            return (pt.x >= left) & (pt.x < right) &
-                   (pt.y >= top) & (pt.y < bottom);
+            return pt.x >= left && pt.x < right && pt.y >= top && pt.y < bottom;
         }
 
         constexpr bool contains(const rect& rc) const noexcept
         {
-            return (rc.left >= left) & (rc.top >= top) &
-                   (rc.right <= right) & (rc.bottom <= bottom);
+            return rc.left >= left && rc.top >= top && rc.right <= right && rc.bottom <= bottom;
         }
 
         template<typename T = CoordType>

src/inc/til/rle.h

@@ -3,8 +3,6 @@
 
 #pragma once
 
-#include "small_vector.h"
-
 #ifdef UNIT_TESTING
 class RunLengthEncodingTests;
 #endif

src/inc/til/size.h

@@ -39,7 +39,7 @@ namespace til // Terminal Implementation Library. Also: "Today I Learned"
 
         constexpr explicit operator bool() const noexcept
         {
-            return (width > 0) & (height > 0);
+            return width > 0 && height > 0;
         }
 
         constexpr size operator+(const size other) const

src/inc/til/small_vector.h

@@ -652,7 +652,7 @@ namespace til
         reference emplace_back(Args&&... args)
         {
             const auto new_size = _ensure_fits(1);
-            const auto it = new (_data + _size) T(std::forward<Args>(args)...);
+            const auto it = std::construct_at(_data + _size, std::forward<Args>(args)...);
             _size = new_size;
             return *it;
         }
@@ -930,7 +930,10 @@ namespace til
         T* _data;
         size_t _capacity;
         size_t _size;
-        T _buffer[N];
+        union
+        {
+            T _buffer[N];
+        };
     };
 }
 

src/renderer/atlas/BackendD3D.h

@@ -5,7 +5,6 @@
 
 #include <stb_rect_pack.h>
 #include <til/flat_set.h>
-#include <til/small_vector.h>
 
 #include "Backend.h"
 

src/renderer/gdi/paint.cpp

@@ -4,8 +4,6 @@
 #include "precomp.h"
 #include "gdirenderer.hpp"
 
-#include <til/small_vector.h>
-
 #include "../inc/unicode.hpp"
 
 #pragma hdrstop