STACK_EXE environment variable

Author: snoyberg

ChangeLog.md

@@ -11,6 +11,7 @@
 * `stack exec` accepts the `--no-ghc-package-path` parameter
 * Don't require build plan to upload [#400](https://github.com/commercialhaskell/stack/issues/400)
 * Specifying test components only builds/runs those tests [#398](https://github.com/commercialhaskell/stack/issues/398)
+* `STACK_EXE` environment variable
 
 Bug fixes:
 

src/Stack/Build/Execute.hs

@@ -521,6 +521,7 @@ withSingleContext ActionContext {..} ExecuteEnv {..} task@Task {..} inner0 =
         menv <- liftIO $ configEnvOverride config EnvSettings
             { esIncludeLocals = taskLocation task == Local
             , esIncludeGhcPackagePath = False
+            , esStackExe = False
             }
         exeName <- liftIO $ join $ findExecutable menv "runhaskell"
         distRelativeDir' <- distRelativeDir
@@ -716,6 +717,7 @@ singleTest ac ee task =
             menv <- liftIO $ configEnvOverride config EnvSettings
                 { esIncludeLocals = taskLocation task == Local
                 , esIncludeGhcPackagePath = True
+                , esStackExe = True
                 }
             if exists
                 then do

src/Stack/Exec.hs

@@ -23,6 +23,7 @@ defaultEnvSettings :: EnvSettings
 defaultEnvSettings = EnvSettings
     { esIncludeLocals = True
     , esIncludeGhcPackagePath = True
+    , esStackExe = True
     }
 
 -- | Execute a process within the Stack configured environment.

src/Stack/Setup.hs

@@ -56,6 +56,7 @@ import           Stack.Solver (getGhcVersion)
 import           Stack.Types
 import           Stack.Types.StackT
 import           System.Directory (doesDirectoryExist, createDirectoryIfMissing, removeFile)
+import           System.Environment (getExecutablePath)
 import           System.Exit (ExitCode (ExitSuccess))
 import           System.FilePath (searchPathSeparator)
 import qualified System.FilePath as FP
@@ -170,6 +171,8 @@ setupEnv = do
             , [toFilePath globalDB]
             ]
 
+    executablePath <- liftIO getExecutablePath
+
     envRef <- liftIO $ newIORef Map.empty
     let getEnvOverride' es = do
             m <- readIORef envRef
@@ -182,6 +185,10 @@ setupEnv = do
                                 then Map.insert "GHC_PACKAGE_PATH" (mkGPP (esIncludeLocals es))
                                 else id)
 
+                        $ (if esStackExe es
+                                then Map.insert "STACK_EXE" (T.pack executablePath)
+                                else id)
+
                         -- For reasoning and duplication, see: https://github.com/fpco/stack/issues/70
                         $ Map.insert "HASKELL_PACKAGE_SANDBOX" (T.pack $ toFilePath deps)
                         $ Map.insert "HASKELL_PACKAGE_SANDBOXES"

src/Stack/Types/Config.hs

@@ -158,6 +158,8 @@ data EnvSettings = EnvSettings
     -- ^ include local project bin directory, GHC_PACKAGE_PATH, etc
     , esIncludeGhcPackagePath :: !Bool
     -- ^ include the GHC_PACKAGE_PATH variable
+    , esStackExe :: !Bool
+    -- ^ set the STACK_EXE variable to the current executable name
     }
     deriving (Show, Eq, Ord)
 
@@ -689,6 +691,7 @@ getMinimalEnvOverride = do
     liftIO $ configEnvOverride config EnvSettings
                     { esIncludeLocals = False
                     , esIncludeGhcPackagePath = False
+                    , esStackExe = False
                     }
 
 data ProjectAndConfigMonoid

src/main/Main.hs

@@ -151,6 +151,10 @@ main =
                                     <*> boolFlags True
                                             "ghc-package-path"
                                             "setting the GHC_PACKAGE_PATH variable for the subprocess"
+                                            idm
+                                    <*> boolFlags True
+                                            "stack-exe"
+                                            "setting the STACK_EXE environment variable to the path for the stack executable"
                                             idm))
              addCommand "ghc"
                         "Run ghc"