Inconsistent behavior for relative paths in runProcess

This was initially reported as a bug in cabal:

https://github.com/haskell/cabal/issues/1058

The relevant fix demonstrates the issue:

https://github.com/snoyberg/cabal/commit/48082b90726093298df8559b365ed08805ca6d8f

It seems that on Linux, a relative path for the executable is derived from the new working directory, whereas on Mac it is derived from the old working directory. (I have not tested on other systems.) Ideally, the behavior would be consistent across OSes, which IMO the more intuitive behavior being the current Mac behavior. The simplest solution would be to always turn the relative paths into absolute paths before changing working directories. However, doing so may introduce a performance hit.

Alternatively, a documentation fix would be good so that it's at least obvious that behavior is platform-specific. I can write a patch for either the change in behavior or the updated documentation, I'd just like to know which is preferred.

Trac metadata

Trac field	Value
Version	7.6.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	libraries/process
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