Add support for copy --one-shot. (haskell#3287)

Signed-off-by: Edward Z. Yang <[email protected]>

Cabal/Distribution/Simple/Install.hs

@@ -56,14 +56,21 @@ install :: PackageDescription -- ^information from the .cabal file
         -> LocalBuildInfo -- ^information from the configure step
         -> CopyFlags -- ^flags sent to copy or install
         -> IO ()
-install pkg_descr lbi flags = do
-  let distPref  = fromFlag (copyDistPref flags)
-      verbosity = fromFlag (copyVerbosity flags)
-      copydest  = fromFlag (copyDest flags)
-
-  unless (hasLibs pkg_descr || hasExes pkg_descr) $
-      die "No executables and no library found. Nothing to do."
-
+install pkg_descr lbi flags
+ | fromFlag (copyOneShot flags) = do
+  checkHasLibsOrExes
+  targets <- readBuildTargets pkg_descr (copyArgs flags)
+  targets' <- checkBuildTargets verbosity pkg_descr targets
+  case targets' of
+    [] -> copyPackage verbosity pkg_descr lbi distPref copydest
+    [(cname, _)] ->
+      let clbi = getComponentLocalBuildInfo lbi cname
+          comp = getComponent pkg_descr cname
+      in copyComponent verbosity pkg_descr lbi comp clbi copydest
+    _ -> die "In --one-shot mode you can only copy a single target"
+
+ | otherwise = do
+  checkHasLibsOrExes
   targets <- readBuildTargets pkg_descr (copyArgs flags)
   targets' <- checkBuildTargets verbosity pkg_descr targets
 
@@ -72,6 +79,14 @@ install pkg_descr lbi flags = do
   -- It's not necessary to do these in build-order, but it's harmless
   withComponentsInBuildOrder pkg_descr lbi (map fst targets') $ \comp clbi ->
     copyComponent verbosity pkg_descr lbi comp clbi copydest
+ where
+  distPref  = fromFlag (copyDistPref flags)
+  verbosity = fromFlag (copyVerbosity flags)
+  copydest  = fromFlag (copyDest flags)
+
+  checkHasLibsOrExes =
+    unless (hasLibs pkg_descr || hasExes pkg_descr) $
+      die "No executables and no library found. Nothing to do."
 
 -- | Copy package global files.
 copyPackage :: Verbosity -> PackageDescription

Cabal/Distribution/Simple/Setup.hs

@@ -825,6 +825,7 @@ data CopyFlags = CopyFlags {
     copyDest      :: Flag CopyDest,
     copyDistPref  :: Flag FilePath,
     copyVerbosity :: Flag Verbosity,
+    copyOneShot   :: Flag Bool,
     -- This is the same hack as in 'buildArgs'.  But I (ezyang) don't
     -- think it's a hack, it's the right way to make hooks more robust
     copyArgs :: [String]
@@ -836,6 +837,7 @@ defaultCopyFlags  = CopyFlags {
     copyDest      = Flag NoCopyDest,
     copyDistPref  = NoFlag,
     copyVerbosity = Flag normal,
+    copyOneShot   = Flag False,
     copyArgs      = []
   }
 
@@ -865,6 +867,11 @@ copyCommand = CommandUI
          copyDistPref (\d flags -> flags { copyDistPref = d })
          showOrParseArgs
 
+      , option "" ["one-shot"]
+          "One-shot copy"
+          copyOneShot (\c flags -> flags { copyOneShot = c })
+          trueArg
+
       ,option "" ["destdir"]
          "directory to copy files to, prepended to installation directories"
          copyDest (\v flags -> flags { copyDest = v })

cabal-install/Distribution/Client/ProjectPlanning.hs

@@ -2134,6 +2134,7 @@ setupHsCopyFlags _ _ verbosity builddir =
       copyArgs      = [], -- TODO: could use this to only copy what we enabled
       copyDest      = toFlag InstallDirs.NoCopyDest,
       copyDistPref  = toFlag builddir,
+      copyOneShot   = toFlag False,
       copyVerbosity = toFlag verbosity
     }