fix many digits

Author: hmcty

lib/std/fmt/parse_float.zig

@@ -149,9 +149,9 @@ test "#11169" {
 }
 
 test "many_digits hex" {
-    // const a: f32 = try std.fmt.parseFloat(f32, "0xffffffffffffffff.0p0"); // This fails btw.
-    // const b: f32 = @floatCast(try std.fmt.parseFloat(f128, "0xffffffffffffffff.0p0"));
-    // try std.testing.expectEqual(a, b);
+    const a: f32 = try parseFloat(f32, "0xffffffffffffffff.0p0");
+    const b: f32 = @floatCast(try parseFloat(f128, "0xffffffffffffffff.0p0"));
+    try std.testing.expectEqual(a, b);
 }
 
 test "hex.special" {
@@ -160,6 +160,7 @@ test "hex.special" {
     try testing.expect(math.isPositiveInf(try parseFloat(f32, "+Inf")));
     try testing.expect(math.isNegativeInf(try parseFloat(f32, "-iNf")));
 }
+
 test "hex.zero" {
     try testing.expectEqual(@as(f32, 0.0), try parseFloat(f32, "0x0"));
     try testing.expectEqual(@as(f32, 0.0), try parseFloat(f32, "-0x0"));

lib/std/fmt/parse_float/FloatInfo.zig

@@ -113,7 +113,7 @@ pub fn from(comptime T: type) Self {
             .max_exponent_fast_path_disguised = 46,
             .max_mantissa_fast_path = 2 << std.math.floatMantissaBits(T),
             // Slow + Eisel-Lemire
-            .mantissa_explicit_bits = std.math.floatMantissaBits(T) - 1,
+            .mantissa_explicit_bits = std.math.floatFractionalBits(T),
             .infinite_power = 0x7fff,
             // Eisel-Lemire.
             // NOTE: Not yet tested (no f80 eisel-lemire implementation)

lib/std/fmt/parse_float/convert_hex.zig

@@ -29,7 +29,7 @@ pub fn convertHex(comptime T: type, n_: Number(T)) T {
     const exp_bits = math.floatExponentBits(T);
     const exp_bias = min_exp - 1;
 
-    // mantissa now implicitly divided by 2^mantissa_bits
+    // mantissa now implicitly divided by 2^fractional_bits
     n.exponent += fractional_bits;
 
     // Shift mantissa and exponent to bring representation into float range.