Add comptime_float support to std.math.is(Positive/Negative)Zero

Author: Danielkonge

lib/std/math/iszero.zig

@@ -5,36 +5,50 @@ const expect = std.testing.expect;
 /// Returns whether x is positive zero.
 pub inline fn isPositiveZero(x: anytype) bool {
     const T = @TypeOf(x);
-    const bit_count = @typeInfo(T).float.bits;
+    const bit_count, const F = switch (@typeInfo(T)) {
+        .float => |float| .{ float.bits, T },
+        .comptime_float => .{ 128, f128 },
+        else => @compileError("unknown floating point type " ++ @typeName(T)),
+    };
     const TBits = std.meta.Int(.unsigned, bit_count);
-    return @as(TBits, @bitCast(x)) == @as(TBits, 0);
+    return @as(TBits, @bitCast(@as(F, x))) == @as(TBits, 0);
 }
 
 /// Returns whether x is negative zero.
 pub inline fn isNegativeZero(x: anytype) bool {
     const T = @TypeOf(x);
-    const bit_count = @typeInfo(T).float.bits;
+    const bit_count, const F = switch (@typeInfo(T)) {
+        .float => |float| .{ float.bits, T },
+        .comptime_float => .{ 128, f128 },
+        else => @compileError("unknown floating point type " ++ @typeName(T)),
+    };
     const TBits = std.meta.Int(.unsigned, bit_count);
-    return @as(TBits, @bitCast(x)) == @as(TBits, 1) << (bit_count - 1);
+    return @as(TBits, @bitCast(@as(F, x))) == @as(TBits, 1) << (bit_count - 1);
 }
 
 test isPositiveZero {
-    inline for ([_]type{ f16, f32, f64, f80, f128 }) |T| {
+    inline for ([_]type{ f16, f32, f64, f80, f128, comptime_float }) |T| {
         try expect(isPositiveZero(@as(T, 0.0)));
         try expect(!isPositiveZero(@as(T, -0.0)));
         try expect(!isPositiveZero(math.floatMin(T)));
         try expect(!isPositiveZero(math.floatMax(T)));
+
+        if (T == comptime_float) return;
+
         try expect(!isPositiveZero(math.inf(T)));
         try expect(!isPositiveZero(-math.inf(T)));
     }
 }
 
 test isNegativeZero {
-    inline for ([_]type{ f16, f32, f64, f80, f128 }) |T| {
+    inline for ([_]type{ f16, f32, f64, f80, f128, comptime_float }) |T| {
         try expect(isNegativeZero(@as(T, -0.0)));
         try expect(!isNegativeZero(@as(T, 0.0)));
         try expect(!isNegativeZero(math.floatMin(T)));
         try expect(!isNegativeZero(math.floatMax(T)));
+
+        if (T == comptime_float) return;
+
         try expect(!isNegativeZero(math.inf(T)));
         try expect(!isNegativeZero(-math.inf(T)));
     }