Force CopyAssumeDepsUpToDate on Windows to test absolute install path behavior.

Signed-off-by: Edward Z. Yang <ezyang@cs.stanford.edu>

Cabal/Cabal.cabal

@@ -92,6 +92,7 @@ extra-source-files:
   tests/PackageTests/Configure/X11.cabal
   tests/PackageTests/CopyAssumeDepsUpToDate/CopyAssumeDepsUpToDate.cabal
   tests/PackageTests/CopyAssumeDepsUpToDate/Main.hs
+  tests/PackageTests/CopyAssumeDepsUpToDate/P.hs
   tests/PackageTests/CopyComponent/Exe/Main.hs
   tests/PackageTests/CopyComponent/Exe/Main2.hs
   tests/PackageTests/CopyComponent/Exe/myprog.cabal

Cabal/Distribution/Simple/Build/PathsModule.hs

@@ -206,6 +206,11 @@ generate pkg_descr lbi clbi =
           where var' = pkgPathEnvVar pkg_descr var
 
         -- In several cases we cannot make relocatable installations
+        -- WARNING: The CopyOneShot package test hacks
+        -- @absolute == True@ to disable relocatable programs
+        -- by giving the package a library as well.  If you change
+        -- this logic (e.g., we start to support relocatable libraries
+        -- by default) you will need to update this test.
         absolute =
              hasLibs pkg_descr        -- we can only make progs relocatable
           || isNothing flat_bindirrel -- if the bin dir is an absolute path

Cabal/tests/PackageTests/CopyAssumeDepsUpToDate/CopyAssumeDepsUpToDate.cabal

@@ -8,6 +8,13 @@ cabal-version:       >=1.10
 
 data-files: data
 
+-- This library purely exists to convince Cabal on Windows
+-- to not attempt to install this as prefix-relative executable.
+library
+  exposed-modules:     P
+  build-depends:       base
+  default-language:    Haskell2010
+
 executable myprog
   main-is:             Main.hs
   other-modules:       Paths_CopyAssumeDepsUpToDate

Cabal/tests/PackageTests/CopyAssumeDepsUpToDate/P.hs

+module P where

Cabal/tests/PackageTests/Tests.hs

@@ -427,6 +427,10 @@ tests config = do
         >>= assertOutputContains "a1 b2"
 
   -- Test copy --assume-deps-up-to-date
+  -- NB: This test has a HORRIBLE HORRIBLE hack to ensure that
+  -- on Windows, we don't try to make a prefix relative package;
+  -- specifically, we give the package under testing a library
+  -- so that we don't attempt to make it prefix relative.
   mtc "CopyAssumeDepsUpToDate" $ \step -> do
     withPackageDb $ do
       step "Initial build"
@@ -448,7 +452,7 @@ tests config = do
 
       step "Install executable"
       liftIO $ writeFile (pkg_dir </> "data") "bbb"
-      cabal "copy" ["--assume-deps-up-to-date", "myprog"]
+      cabal "copy" ["--assume-deps-up-to-date", "exe:myprog"]
       runInstalledExe' "myprog" []
         >>= assertOutputContains "aaa"