[GHC] #12494: Implementation of setenv in base incorrectly claims empty environment variable not supported on Windows

[GHC]

#12494: Implementation of setenv in base incorrectly claims empty environment
variable not supported on Windows
-------------------------------------+-------------------------------------
        Reporter:  ezyang            |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  libraries/base    |              Version:  8.0.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by bergmark):

 I think it's important to make sure that there is some kind of
 mention/warning to let users know that their code changed because of
 this. I see three ways to accomplish this:

 * Deprecate `setEnv` and add the new function under a new name
 * Add a warning pragma for one release cycle and then make the change
 * Change the parameter to only accept non-empty strings

 What about staying compatible with several versions of base? Should users
 never use an empty string (effectively banning the use of empty env vars),
 and/or should we refer users to the base-compat package?

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12494#comment:1>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler