From 195bfbf0f5ab63520817fe0661d23952cf852ec1 Mon Sep 17 00:00:00 2001
From: Michael Snoyman <michael@snoyman.com>
Date: Thu, 11 Aug 2016 13:40:03 +0300
Subject: [PATCH] Replace runghc with ghc -e Main.main

Motivation: if you call `runghc`, that process continues to live on
separate from the actual `ghc` process that interprets the code. That's
inefficient. But more worryingly: the `runghc` process itself can cause
major problems in Docker images, since it ends up swallowing SIGINTs as
the PID-1 process. This was discussed quite a bit on Twitter:

https://twitter.com/argumatronic/status/763418990982991872
---
 src/main/Main.hs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/main/Main.hs b/src/main/Main.hs
index 3f81121fa2..176fc4b3a8 100644
--- a/src/main/Main.hs
+++ b/src/main/Main.hs
@@ -715,7 +715,7 @@ execCmd ExecOpts {..} go@GlobalOpts{..} =
             (cmd, args) <- case (eoCmd, eoArgs) of
                  (ExecCmd cmd, args) -> return (cmd, args)
                  (ExecGhc, args) -> return ("ghc", args)
-                 (ExecRunGhc, args) -> return ("runghc", args)
+                 (ExecRunGhc, args) -> return ("ghc", "-e" : "Main.main" : args)
             (manager,lc) <- liftIO $ loadConfigWithOpts go
             withUserFileLock go (configStackRoot $ lcConfig lc) $ \lk -> do
               compilerVersion <- loadCompilerVersion manager go lc
@@ -742,7 +742,7 @@ execCmd ExecOpts {..} go@GlobalOpts{..} =
                    (ExecGhc, args) -> execCompiler "" args
                     -- NOTE: this won't currently work for GHCJS, because it doesn't have
                     -- a runghcjs binary. It probably will someday, though.
-                   (ExecRunGhc, args) -> execCompiler "run" args
+                   (ExecRunGhc, args) -> execCompiler "" ("-e" : "Main.main" : args)
                let targets = concatMap words eoPackages
                unless (null targets) $
                    Stack.Build.build (const $ return ()) lk defaultBuildOptsCLI