Add comptime_float support to std.math.isNormal

Author: Danielkonge

lib/std/math/isnormal.zig

@@ -4,7 +4,7 @@ const expect = std.testing.expect;
 
 /// Returns whether x is neither zero, subnormal, infinity, or NaN.
 pub fn isNormal(x: anytype) bool {
-    const T = @TypeOf(x);
+    const T = if (@TypeOf(x) == comptime_float) f128 else @TypeOf(x);
     const TBits = std.meta.Int(.unsigned, @typeInfo(T).float.bits);
 
     const increment_exp = 1 << math.floatMantissaBits(T);
@@ -15,14 +15,14 @@ pub fn isNormal(x: anytype) bool {
     // The sign bit is removed because all ones would overflow into it.
     // For f80, even though it has an explicit integer part stored,
     // the exponent effectively takes priority if mismatching.
-    const value = @as(TBits, @bitCast(x)) +% increment_exp;
+    const value = @as(TBits, @bitCast(@as(T, x))) +% increment_exp;
     return value & remove_sign >= (increment_exp << 1);
 }
 
 test isNormal {
     // TODO add `c_longdouble' when math.inf(T) supports it
-    inline for ([_]type{ f16, f32, f64, f80, f128 }) |T| {
-        const TBits = std.meta.Int(.unsigned, @bitSizeOf(T));
+    inline for ([_]type{ f16, f32, f64, f80, f128, comptime_float }) |T| {
+        const TBits = if (T == comptime_float) u128 else std.meta.Int(.unsigned, @bitSizeOf(T));
 
         // normals
         try expect(isNormal(@as(T, 1.0)));
@@ -35,7 +35,10 @@ test isNormal {
         try expect(!isNormal(@as(T, math.floatTrueMin(T))));
 
         // largest subnormal
-        try expect(!isNormal(@as(T, @bitCast(~(~@as(TBits, 0) << math.floatFractionalBits(T))))));
+        const large_subnormal: if (T == comptime_float) f128 else T = @bitCast(~(~@as(TBits, 0) << math.floatFractionalBits(T)));
+        try expect(!isNormal(@as(T, large_subnormal)));
+
+        if (T == comptime_float) return;
 
         // non-finite numbers
         try expect(!isNormal(-math.inf(T)));