From 728ad1a1e066da453ae13ee479629c00d8c2f32d Mon Sep 17 00:00:00 2001
From: Tamar Christina <tamar@zhox.com>
Date: Sat, 3 Mar 2018 20:51:03 +0000
Subject: [PATCH] Conditionally define values (#5182)
(cherry picked from commit 2d222368c79733f9948dc9bb952c0e7fd3453cd0)
---
Cabal/Distribution/Compat/Environment.hs | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/Cabal/Distribution/Compat/Environment.hs b/Cabal/Distribution/Compat/Environment.hs
index 014fad7a87..7194d720a4 100644
--- a/Cabal/Distribution/Compat/Environment.hs
+++ b/Cabal/Distribution/Compat/Environment.hs
@@ -31,6 +31,9 @@ import Distribution.Compat.Stack
#ifdef mingw32_HOST_OS
import Foreign.C
+#if __GLASGOW_HASKELL__ < 708
+import Foreign.Ptr (nullPtr)
+#endif
import GHC.Windows
#else
import Foreign.C.Types
@@ -123,6 +126,12 @@ unsetEnv key = withCWString key $ \k -> do
err <- c_GetLastError
unless (err == eRROR_ENVVAR_NOT_FOUND) $ do
throwGetLastError "unsetEnv"
+
+eRROR_ENVVAR_NOT_FOUND :: DWORD
+eRROR_ENVVAR_NOT_FOUND = 203
+
+foreign import WINDOWS_CCONV unsafe "windows.h GetLastError"
+ c_GetLastError:: IO DWORD
#else
unsetEnv key = withFilePath key (throwErrnoIf_ (/= 0) "unsetEnv" . c_unsetenv)
#if __GLASGOW_HASKELL__ > 706
--
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