Don't use installedPkgs for internal library library dirs.

In 1.24, installedPkgs contained only references to the external package
database, not any internal libraries. In particular, when we built a
dynamically linked executable, installedPkgs did NOT have a reference to
the internal library; instead, depLibraryPaths has a special case
(hasInternalDeps) to add the final libdir to the RPATH.

In HEAD, after 0d15ede, we started adding internal libraries (with the
INPLACE registrations) to installedPkgs to fix haskell#2971.  But depLibraryPaths
was not updated, which means that the inplace registrations got picked
up and added to the RPATH, resulting in bad temporary directories
showing up in RPATHs.

In this commit, we just filter out internal entries from installedPkgs
and compute the library dirs for them from scratch (this code already
existed, so no loss!)

Fixes haskell#4025.

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

Cabal/Cabal.cabal

@@ -271,6 +271,9 @@ extra-source-files:
   tests/PackageTests/Regression/T3294/T3294.cabal
   tests/PackageTests/Regression/T3847/Main.hs
   tests/PackageTests/Regression/T3847/T3847.cabal
+  tests/PackageTests/Regression/T4025/A.hs
+  tests/PackageTests/Regression/T4025/T4025.cabal
+  tests/PackageTests/Regression/T4025/exe/Main.hs
   tests/PackageTests/TemplateHaskell/dynamic/Exe.hs
   tests/PackageTests/TemplateHaskell/dynamic/Lib.hs
   tests/PackageTests/TemplateHaskell/dynamic/TH.hs

Cabal/Distribution/Simple/LocalBuildInfo.hs

@@ -268,13 +268,23 @@ depLibraryPaths inplace relative lbi clbi = do
           | inplace    = componentBuildDir lbi sub_clbi
           | otherwise  = dynlibdir (absoluteComponentInstallDirs pkgDescr lbi (componentUnitId sub_clbi) NoCopyDest)
 
-    let ipkgs          = allPackages (installedPkgs lbi)
+    -- Why do we go through all the trouble of a hand-crafting
+    -- internalLibs, when 'installedPkgs' actually contains the
+    -- internal libraries?  The trouble is that 'installedPkgs'
+    -- may contain *inplace* entries, which we must NOT use for
+    -- not inplace 'depLibraryPaths' (e.g., for RPATH calculation).
+    -- See #4025 for more details. This is all horrible but it
+    -- is a moot point if you are using a per-component build,
+    -- because you never have any internal libraries in this case;
+    -- they're all external.
+    let external_ipkgs = filter is_external (allPackages (installedPkgs lbi))
+        is_external ipkg = not (installedUnitId ipkg `elem` internalDeps)
         -- First look for dynamic libraries in `dynamic-library-dirs`, and use
         -- `library-dirs` as a fall back.
         getDynDir pkg  = case Installed.libraryDynDirs pkg of
                            [] -> Installed.libraryDirs pkg
                            d  -> d
-        allDepLibDirs  = concatMap getDynDir ipkgs
+        allDepLibDirs  = concatMap getDynDir external_ipkgs
 
         allDepLibDirs' = internalLibs ++ allDepLibDirs
     allDepLibDirsC <- traverse canonicalizePathNoFail allDepLibDirs'

Cabal/tests/PackageTests/Regression/T4025/A.hs

@@ -0,0 +1,4 @@
+module A where
+{-# NOINLINE a #-}
+a :: Int
+a = 23

Cabal/tests/PackageTests/Regression/T4025/T4025.cabal

@@ -0,0 +1,13 @@
+name: T4025
+version: 1.0
+build-type: Simple
+cabal-version: >= 1.10
+
+library
+  build-depends: base
+  exposed-modules: A
+
+executable exe
+  build-depends: T4025, base
+  hs-source-dirs: exe
+  main-is: Main.hs

Cabal/tests/PackageTests/Regression/T4025/exe/Main.hs

@@ -0,0 +1,2 @@
+import A
+main = print a

Cabal/tests/PackageTests/Tests.hs

@@ -539,6 +539,19 @@ tests config = do
   -- Test that we pick up include dirs from internal library
   tc "Regression/T2971a" $ cabal_build []
 
+  -- Test that we don't accidentally add the inplace directory to
+  -- an executable RPATH.  Don't test on Windows, which doesn't
+  -- support RPATH.
+  unlessWindows $ do
+    tc "Regression/T4025" $ do
+      cabal "configure" ["--enable-executable-dynamic"]
+      cabal "build" []
+      -- This should fail as it we should NOT be able to find the
+      -- dynamic library for the internal library (since we didn't
+      -- install it).  If we incorrectly encoded our local dist
+      -- dir in the RPATH, this will succeed.
+      shouldFail $ runExe' "exe" []
+
   -- Test error message we report when a non-buildable target is
   -- requested to be built
   -- TODO: We can give a better error message here, see #3858.