From e4a06a26b56dd76d783f2b4e45528ac8ee3028a5 Mon Sep 17 00:00:00 2001
From: Daniel Gröber <dxld@darkboxed.org>
Date: Sun, 12 Aug 2018 04:36:27 +0200
Subject: Add --help option to wrapper

---
 src/CabalHelper/Compiletime/Types.hs   | 5 +++--
 src/CabalHelper/Compiletime/Wrapper.hs | 5 ++++-
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/src/CabalHelper/Compiletime/Types.hs b/src/CabalHelper/Compiletime/Types.hs
index 297f785..07d0266 100644
--- a/src/CabalHelper/Compiletime/Types.hs
+++ b/src/CabalHelper/Compiletime/Types.hs
@@ -26,7 +26,8 @@ module CabalHelper.Compiletime.Types where
 import Data.Version
 
 data Options = Options {
-          oVerbose       :: Bool
+          oHelp          :: Bool
+        , oVerbose       :: Bool
         , oGhcProgram    :: FilePath
         , oGhcPkgProgram :: FilePath
         , oCabalProgram  :: FilePath
@@ -37,4 +38,4 @@ data Options = Options {
 newtype PackageDbDir = PackageDbDir { unPackageDbDir :: FilePath }
 
 defaultOptions :: Options
-defaultOptions = Options False "ghc" "ghc-pkg" "cabal" Nothing Nothing
+defaultOptions = Options False False "ghc" "ghc-pkg" "cabal" Nothing Nothing
diff --git a/src/CabalHelper/Compiletime/Wrapper.hs b/src/CabalHelper/Compiletime/Wrapper.hs
index 3ea3462..ae936f3 100644
--- a/src/CabalHelper/Compiletime/Wrapper.hs
+++ b/src/CabalHelper/Compiletime/Wrapper.hs
@@ -65,7 +65,9 @@ usage = do
 
 globalArgSpec :: [OptDescr (Options -> Options)]
 globalArgSpec =
-      [ option "" ["verbose"] "Be more verbose" $
+      [ option "h" ["help"] "Display help message" $
+              NoArg $ \o -> o { oHelp = True }
+      , option "" ["verbose"] "Be more verbose" $
               NoArg $ \o -> o { oVerbose = True }
 
       , option "" ["with-ghc"] "GHC executable to use" $
@@ -137,6 +139,7 @@ main = handlePanic $ do
   (opts', args) <- parseCommandArgs defaultOptions <$> getArgs
   opts <- overrideVerbosityEnvVar =<< guessProgramPaths opts'
   case args of
+    _ | oHelp opts -> usage
     [] -> usage
     "help":[] -> usage
     "version":[] -> putStrLn $ showVersion version
-- 
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