Commit 5f31d54064

LemonBoy <thatlemon@gmail.com>
2020-09-02 10:51:15
std: ArrayList.initCapacity now respects the specified cap
Don't use the user-supplied cap as starting point for a resize. Doing so overallocates memory and thus negates the whole point of specifying a precise cap value.
master
1 parent 73a8c9b
Changed files (1)
lib
std
array_list.zig
lib/std/array_list.zig
@@ -46,7 +46,11 @@ pub fn ArrayListAligned(comptime T: type, comptime alignment: ?u29) type {
         /// Deinitialize with `deinit` or use `toOwnedSlice`.
         pub fn initCapacity(allocator: *Allocator, num: usize) !Self {
             var self = Self.init(allocator);
-            try self.ensureCapacity(num);
+
+            const new_memory = try self.allocator.allocAdvanced(T, alignment, num, .at_least);
+            self.items.ptr = new_memory.ptr;
+            self.capacity = new_memory.len;
+
             return self;
         }
 
@@ -366,7 +370,11 @@ pub fn ArrayListAlignedUnmanaged(comptime T: type, comptime alignment: ?u29) typ
         /// Deinitialize with `deinit` or use `toOwnedSlice`.
         pub fn initCapacity(allocator: *Allocator, num: usize) !Self {
             var self = Self{};
-            try self.ensureCapacity(allocator, num);
+
+            const new_memory = try self.allocator.allocAdvanced(T, alignment, num, .at_least);
+            self.items.ptr = new_memory.ptr;
+            self.capacity = new_memory.len;
+
             return self;
         }