Fix assertion failures

Catfish-Man · Catfish-Man · commit da87c55434a7 · 2024-12-06T16:24:32.000-08:00
diff --git a/stdlib/public/core/Array.swift b/stdlib/public/core/Array.swift
@@ -1238,8 +1238,8 @@ extension Array: RangeReplaceableCollection {
     let startNewElements = _buffer.mutableFirstElementAddress + oldCount
     let buf = UnsafeMutableBufferPointer(
                 start: startNewElements,
-                count: _buffer.mutableCapacity - oldCount)
-
+                count: newElementsCount)
+    _debugPrecondition(buf.endIndex <= _buffer.mutableCapacity)
     let end = buf.initialize(fromContentsOf: newElements)
     _precondition(end == buf.endIndex)
     _buffer.mutableCount = _buffer.mutableCount + newElementsCount
diff --git a/stdlib/public/core/ArraySlice.swift b/stdlib/public/core/ArraySlice.swift
@@ -960,8 +960,8 @@ extension ArraySlice: RangeReplaceableCollection {
     let startNewElements = _buffer.firstElementAddress + oldCount
     let buf = UnsafeMutableBufferPointer(
                 start: startNewElements,
-                count: self.capacity - oldCount)
-
+                count: newElementsCount)
+    _debugPrecondition(buf.endIndex <= self.capacity)
     let end = buf.initialize(fromContentsOf: newElements)
     _precondition(end == buf.endIndex)
     _buffer.count += newElementsCount
diff --git a/stdlib/public/core/ContiguousArray.swift b/stdlib/public/core/ContiguousArray.swift
@@ -853,8 +853,8 @@ extension ContiguousArray: RangeReplaceableCollection {
     let startNewElements = _buffer.mutableFirstElementAddress + oldCount
     let buf = UnsafeMutableBufferPointer(
                 start: startNewElements,
-                count: _buffer.mutableCapacity - oldCount)
-
+                count: newElementsCount)
+    _debugPrecondition(buf.endIndex <= _buffer.mutableCapacity)
     let end = buf.initialize(fromContentsOf: newElements)
     _precondition(end == buf.endIndex)
     _buffer.count += newElementsCount
