Unix.symlink does not support forward slashes under Windows

[vicuna]

Original bug ID: 7564
Reporter: @nojb
Assigned to: @alainfrisch
Status: resolved (set by @alainfrisch on 2017-07-18T22:05:42Z)
Resolution: fixed
Priority: normal
Severity: minor
Fixed in version: 4.06.0 +dev/beta1/beta2/rc1
Category: platform support (windows, cross-compilation, etc)

Bug description

It appears that the target of native Windows symlinks (as created by Unix.symlink under Windows) must necessarily use backward slashes. Otherwise the native Windows APIs will think that the target does not exist.

As a compatibility layer, Unix.symlink should allow forward slashes in its argument.

Steps to reproduce

$ cd /tmp
$ ocaml unix.cma
# Unix.mkdir "foo" 0o777;;
- : unit = ()
# close_out (open_out "foo/test.txt");;
- : unit = ()
# Unix.symlink "foo/test.txt" "foolink";;
- : unit = ()
# Unix.stat "foolink";;
Exception: Unix.Unix_error (Unix.ENOENT, "stat", "foolink").
# Unix.symlink "foo\\test.txt" "foolink2";;
- : unit = ()
# Unix.stat "foolink2";;
- : Unix.stats =
{Unix.st_dev = -427248956; st_ino = 2456; st_kind = Unix.S_REG;
 st_perm = 438; st_nlink = 1; st_uid = 0; st_gid = 0; st_rdev = -427248956;
 st_size = 0; st_atime = 1498204751.3015687; st_mtime = 1498204751.3015687;
 st_ctime = 1498204751.3015687}

[vicuna]

Comment author: @nojb

https://blogs.msdn.microsoft.com/jeremykuhne/2016/04/21/path-normalization/

[vicuna]

Comment author: @nojb

#1211

[vicuna]

Comment author: @xavierleroy

See work in progress and discussion here: #1211