Use std.math.isPowerOfTwo across std lib

std/hash_map.zig

@@ -157,8 +157,7 @@ pub fn HashMap(comptime K: type, comptime V: type, comptime hash: fn (key: K) u3
         fn ensureCapacityExact(self: *Self, new_capacity: usize) !void {
             // capacity must always be a power of two to allow for modulo
             // optimization in the constrainIndex fn
-            const is_power_of_two = new_capacity & (new_capacity - 1) == 0;
-            assert(is_power_of_two);
+            assert(math.isPowerOfTwo(new_capacity));
 
             if (new_capacity <= self.entries.len) {
                 return;

std/math/big/int.zig

@@ -447,7 +447,7 @@ pub const Int = struct {
         }
 
         // Power of two: can do a single pass and use masks to extract digits.
-        if (base & (base - 1) == 0) {
+        if (math.isPowerOfTwo(base)) {
             const base_shift = math.log2_int(Limb, base);
 
             for (self.limbs[0..self.len()]) |limb| {

std/segmented_list.zig

@@ -80,9 +80,9 @@ pub fn SegmentedList(comptime T: type, comptime prealloc_item_count: usize) type
         const prealloc_exp = blk: {
             // we don't use the prealloc_exp constant when prealloc_item_count is 0.
             assert(prealloc_item_count != 0);
+            assert(std.math.isPowerOfTwo(prealloc_item_count));
 
             const value = std.math.log2_int(usize, prealloc_item_count);
-            assert((1 << value) == prealloc_item_count); // prealloc_item_count must be a power of 2
             break :blk @typeOf(1)(value);
         };
         const ShelfIndex = std.math.Log2Int(usize);