CL in question is https://golang.org/cl/109235 .

testDirLinks in os/os_windows_test.go certainly implies that os.SameFile works for directories on WIndows.

/cc @alexbrainman @bradfitz (from the CL)

Change https://golang.org/cl/118738 mentions this issue: cmd/go: don't assume that GOOS="windows" implies case insensitive filesystem

send reply to the issue:

https://golang.org/cl/109235 changed the meaning of directory patterns to do case-insensitive matches on Windows. This is not correct behavior.

Why CL 109235 is not correct behavior? Do you know of a setup where TestCDAndGOPATHAreDifferent fails?

I did some experiment at home. I have Linux computer that runs Samba software, that allows some Linux directories accessible to Windows computers on the network. so I created directory with 2 sub-directories having same name, just different case, and have different contents. Just like:

$ find
.
./test
./test/small
./TEST
./TEST/LARGE
$

And then I mounted that directory on my Windows computer. That is what I see:

U:\>dir /b u:\z\
TEST
test

U:\>dir /b u:\z\TEST\
small

U:\>dir /b u:\z\test
small

U:\>

cmd.exe uses same API as Go programs do, so Go programs will see exactly the same thing.

Something https://blogs.msdn.microsoft.com/commandline/2018/02/28/per-directory-case-sensitivity-and-wsl/ I have found while googling for this issue. Perhaps it is related.

Alex

@rsc can you take a look at the CL that @bradfitz sent out and see if his solution is the one you're looking for? There seems to be disagreement on the right solution here.

The original CL 109235 was addressing a real bug (in its commit message) but the problem is not that the pattern match algorithm was wrong. The problem is that the pattern going into the match was wrong. Bad inputs not bad outputs. I'll take a look at an alternate fix for that real issue.

Change https://golang.org/cl/129059 mentions this issue: cmd/go: fix -gcflags, -ldflags not applying to current directory