#7415: Add more error code support to GHC.Windows (patch)
----------------------------+-----------------------------------------------
Reporter: joeyadams | Owner:
Type: feature request | Status: new
Priority: normal | Component: libraries/base
Version: 7.6.1 | Keywords:
Os: Windows | Architecture: Unknown/Multiple
Failure: None/Unknown | Blockedby:
Blocking: 7353 | Related:
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This patch adds some infrastructure for the
[http://hackage.haskell.org/trac/ghc/ticket/7353 Windows I/O manager]
currently in progress. It organizes `GHC.Windows` a little, and adds some
things:
* A `LPWSTR` type alias. I'm not a Windows expert, but I think we should
avoid [http://msdn.microsoft.com/en-
us/library/windows/desktop/aa383751%28v=vs.85%29.aspx#lptstr LPTSTR] in
our FFI declarations. It depends on whether or not the `UNICODE` macro is
defined—a notion that makes little sense in a Haskell program. Using
`LPWSTR` makes our intention clearer.
I left `LPTSTR` in for compatibility. Should we DEPRECATE it?
* `c_maperrno_func`. The existing `c_maperrno` calls `GetLastError`,
converts the result, then sets `errno`. `c_maperrno_func` exposes the
conversion as a pure function.
This helps eliminate a caveat in
[http://www.haskell.org/ghc/docs/latest/html/libraries/Win32/System-
Win32-Types.html#v:failWith failWith], which expects `GetLastError` to
return the error passed to `failWith`. This is not the case, for example,
when throwing the error in another thread.
* `failWith`, `failIf`, ... error guards from
[http://www.haskell.org/ghc/docs/latest/html/libraries/Win32/System-
Win32-Types.html System.Win32.Types].
* `ErrCode`, `getLastError`, `getErrorMessage`, `errCodeToIOError`: Lets
you work with the system error code more directly.
* `iNVALID_HANDLE_VALUE`
Behavior change: `throwGetLastError` now attaches the system error
message, making it (almost) equivalent to
[http://www.haskell.org/ghc/docs/latest/html/libraries/Win32/System-
Win32-Types.html#v:errorWin errorWin] from `System.Win32.Types`.
Moreover, it no longer has the side effect of setting `errno`, thanks to
`c_maperrno_func`.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7415>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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