"stack ghci" now replaces the process with ghci for signal handling #3821

Author: mgsloan

ChangeLog.md

@@ -86,6 +86,13 @@ Bug fixes:
   we were forgetting to record the result, which meant that all tests
   always ran even if they had already passed before. See
   [#3770](https://github.com/commercialhaskell/stack/pull/3770).
+* `stack ghci` now replaces the stack process with ghci. This improves
+  signal handling behavior. In particular, handling of Ctrl-C.  To make
+  this possible, the generated files are now left behind after exit.
+  The paths are based on hashing file contents, and it's stored in the
+  system temporary directory, so this shouldn't result in too much
+  garbage. See
+  [#3821](https://github.com/commercialhaskell/stack/issues/3821).
 
 ## v1.6.3
 

src/Stack/Ghci.hs

@@ -50,7 +50,7 @@ import           Stack.Types.PackageName
 import           Stack.Types.Runner
 import           System.IO (putStrLn, putStr, getLine)
 import           System.IO.Temp (getCanonicalTemporaryDirectory)
-import           RIO.Process (withEnvOverride, execSpawn, execObserve)
+import           RIO.Process (withEnvOverride, exec, execObserve)
 
 #ifndef WINDOWS
 import qualified System.Posix.Files as Posix
@@ -367,7 +367,7 @@ runGhci GhciOpts{..} targets mainIsTargets pkgs extraFiles exposePackages = do
          T.intercalate ", " (map (packageNameText . ghciPkgName) pkgs))
     let execGhci extras = do
             menv <- liftIO $ configEnvOverrideSettings config defaultEnvSettings
-            withEnvOverride menv $ execSpawn
+            withEnvOverride menv $ exec
                  (fromMaybe (compilerExeName wc) ghciGhcCommand)
                  (("--interactive" : ) $
                  -- This initial "-i" resets the include directories to