For the record, this is the program I used to confirm that it's a duplicate:

  #include <stdlib.h>
  #include <stdio.h>

  void main() {
    unsigned short control_word = 0x37f;
      asm ("fldcw %0" : : "m" (control_word));

printf("%lf\n", strtod("283686952306183", NULL));
}

Perhaps it can help if anyone on WSL reports this again.

On 9/25/2019 12:56:35 PM, Anastasios <antonbachin@yahoo.com> wrote:
Having looked into it more, I found this is due to being on WSL, and it is a duplicate of https://github.com/microsoft/WSL/issues/830, which, I see, you are already well aware of. Please excuse the noise.

On 9/25/2019 10:51:53 AM, Rich Felker <dalias@libc.org> wrote:
On Wed, Sep 25, 2019 at 09:32:35AM -0500, Anastasios wrote:
> Hello,
>
> Consider this program, strtod.c:
>
>   #include
>   #include
>
>   int main()
>   {
>       printf("%lf\n", strtod("283686952306183", NULL));
>   }
>
> With current musl master from Git:
>
>   $ musl-gcc -static strtod.c -o a.musl
> $ ./a.musl
> 283686952306176.000000
>
> By comparison, with glibc:
>
> $ gcc -static strtod.c -o a.glibc
> $ ./a.glibc
> 283686952306183.000000
>
> The correct binary representation of this float is
>
> 0x42f0203040506070
>
> but musl strtod produces
>
> 0x42f0203040506000
>
> i.e., it fails to set the LSB. I examined this while ruling out printf as the cause.

I can't reproduce this. My test program for strtod shows, for the
input "283686952306183":

d: 283686952306183 [0x1.020304050607p+48] [42f0203040506070]

I suspect you miscompiled musl, possibly by passing in CFLAGS (perhaps
from defaults in your environment?) that break floating point
semantics. We test for and refuse to build if __FAST_MATH__ is
defined, but GCC only defines it if you use -ffast-math, not if you
manually enable one or more of the individual broken options that
-ffast-math enables.

Alternatively, it's possible that you have a broken compiler version
that miscompiles floating point code.

Rich