std.fmt.parseFloat treats "." as valid float.

Zig Version

0.10.0-dev.1933+5f2d0d414

Steps to Reproduce

const std = @import("std");

test "" {
    const f = try std.fmt.parseFloat(f64, ".");
    try std.testing.expect(f == 0);
}

$ zig build test

Expected Behavior

I would expect this test to fail at the parseFloat call.

Actual Behavior

$ All 1 tests passed.

[arBmind]

I added this test case in #11727 but could not reproduce this issue.

C:\Zig\Tests> C:\Zig\repo\stage1\bin\zig.exe test float.zig

Test [1/1] testTest [1/1] test ""... FAIL (InvalidCharacter)
FAIL (InvalidCharacter)
C:\Zig\repo\lib\std\fmt\parse_float\parse_float.zig:31:9: 0x7ff65c742161 in td.fmt.parse_float.parse_float.parseFloat (test.obj)
        return parse.parseInfOrNan(T, s[i..], negative) orelse error.InvalidCharacter;
        ^
C:\Zig\Tests\float.zig:4:15: 0x7ff65c74176c in est "" (test.obj)
    const f = try std.fmt.parseFloat(f64, ".");
              ^
0 passed; 0 skipped; 1 failed.
error: the following test command failed with exit code 1:

[tiehuis]

Your zig version is slightly out of date. A new float-parser has been recently implemented in master which fixes this issue: see #11566.

The following is true as of current; try testing.expectError(error.InvalidCharacter, parseFloat(f64, "."));.