runtime/race: GORACE="strip_path_prefix..." ignored with Windows paths

[shivakumargn]

With GORACE set, in path like D:\<fullpath> only "D" can stripped and
what remains is :\<fullpath>

":" and later characters in GORACE are ignored.

Example:
 
set GORACE="strip_path_prefix=D:\sources"

D:\sources\gopath\src\learn>go run -race race.go
==================
WARNING: DATA RACE
Read by goroutine 4:
  main.func┬╖002()
      :/sources/gopath/src/learn/race.go:37 +0x56

Previous write by goroutine 1:
  main.main()
      :/sources/gopath/src/learn/race.go:30 +0x1af

Goroutine 4 (running) created at:
  main.main()
      :/sources/gopath/src/learn/race.go:38 +0x19f

Goroutine 1 (running) created at:
  _rt0_go()
      :/sources/golang/src/pkg/runtime/asm_amd64.s:95 +0x117

==================
Found 1 data race(s)
exit status 66

[rsc]

Comment 1:

Have you tried using forward slashes, as in D:/sources ?
I don't know if it will help but maybe.

Status changed to Accepted.

[shivakumargn]

Comment 2:

The problem is not with the path separator but with the removal of ":" itself.
I have tried "\", "/", "\\" for path separator with no difference in result.
I have also tried escaping the ":" with "\".

[dvyukov]

Comment 3:

Owner changed to @dvyukov.

[dvyukov]

Comment 4:

Unfortunately, long time ago somebody decided that ':' is a good delimiter for
parameters, so "strip_path_prefix=c:\foo" becomes just "strip_path_prefix=c", and you
should see that it strips "c" from paths.
Fortunately, the string does not need to be a prefix, so instead of
"strip_path_prefix=c:\foo\bar\", you can set "strip_path_prefix=foo\bar\", and it will
have the same effect.

Status changed to Unfortunate.

[shivakumargn]

Comment 5:

"strip_path_prefix=foo\bar\" has no effect. No stripping happens with this option.

[dvyukov]

Comment 6:

There is something weird with windows env handling.
Try
set GORACE=strip_path_prefix=sources

[dvyukov]

Comment 7:

I mean, I've just checked and it works for me.

[shivakumargn]

Comment 8:

Yes, works partly. Good enough for my needs.
If strip_path_prefix=D:\sources\golang:D:\sources\gopath, stripping is done only for the
first path. Path after ":" is not picked.

[dvyukov]

Comment 9:

As of now, strip_path_prefix value is a single string, there is no support for a list of
paths to strip.