Allow absolute project file when project dir is specified

cabal-install/src/Distribution/Client/CmdClean.hs

@@ -75,7 +75,7 @@ cleanCommand = CommandUI
             cleanProjectDir (\path flags -> flags {cleanProjectDir = path})
             (reqArg "DIR" (succeedReadE Flag) flagToList)
         , option [] ["project-file"]
-            "Set the path of the cabal.project file (relative to the project directory)"
+            "Set the path of the cabal.project file (relative to the project directory when relative)"
             cleanProjectFile (\pf flags -> flags {cleanProjectFile = pf})
             (reqArg "FILE" (succeedReadE Flag) flagToList)
         , option ['s'] ["save-config"]

cabal-install/src/Distribution/Client/DistDirLayout.hs

@@ -168,6 +168,10 @@ data ProjectRoot =
        -- | An explicit project root. It contains the absolute project
        -- root dir and the relative @cabal.project@ file (or explicit override)
      | ProjectRootExplicit FilePath FilePath
+
+       -- | An explicit, absolute project root dir and an explicit, absolute
+       -- @cabal.project@ file.
+     | ProjectRootExplicitAbsolute FilePath FilePath
   deriving (Eq, Show)
 
 defaultProjectFile :: FilePath
@@ -185,8 +189,9 @@ defaultDistDirLayout projectRoot mdistDirectory =
     DistDirLayout {..}
   where
     (projectRootDir, projectFile) = case projectRoot of
-      ProjectRootImplicit dir      -> (dir, dir </> defaultProjectFile)
-      ProjectRootExplicit dir file -> (dir, dir </> file)
+      ProjectRootImplicit dir              -> (dir, dir </> defaultProjectFile)
+      ProjectRootExplicit dir file         -> (dir, dir </> file)
+      ProjectRootExplicitAbsolute dir file -> (dir, file)
 
     distProjectRootDirectory :: FilePath
     distProjectRootDirectory = projectRootDir

cabal-install/src/Distribution/Client/ProjectConfig.hs

@@ -434,7 +434,9 @@ findProjectRoot verbosity mprojectDir mprojectFile = do
           Nothing -> pure $ Right (ProjectRootExplicit projectDir defaultProjectFile)
 
           Just projectFile
-            | isAbsolute projectFile -> left (BadProjectRootAbsoluteFile projectFile)
+            | isAbsolute projectFile -> doesFileExist projectFile >>= \case
+                False -> left (BadProjectRootAbsoluteFile projectFile)
+                True  -> Right . ProjectRootExplicitAbsolute dir <$> canonicalizePath projectFile
 
             | otherwise -> doesFileExist (projectDir </> projectFile) >>= \case
                 False -> left (BadProjectRootDirFile dir projectFile)
@@ -500,7 +502,7 @@ renderBadProjectRoot = \case
     "The given project directory '" <> dir <> "' does not exist."
 
   BadProjectRootAbsoluteFile file ->
-    "The given project file'" <> file <> "' is an absolute path: it must be relative to the project directory."
+    "The given project file '" <> file <> "' does not exist."
 
   BadProjectRootDirFile dir file ->
     "The given project directory/file combination '" <> dir </> file <> "' does not exist."

cabal-install/src/Distribution/Client/ProjectFlags.hs

@@ -21,7 +21,8 @@ data ProjectFlags = ProjectFlags
       -- ^ The project directory.
 
     , flagProjectFile :: Flag FilePath
-      -- ^ The cabal project file path, relative to the project directory; defaults to @cabal.project@.
+      -- ^ The cabal project file path; defaults to @cabal.project@.
+      -- This path, when relative, is relative to the project directory.
       -- The filename portion of the path denotes the cabal project file name, but it also
       -- is the base of auxiliary project files, such as
       -- @cabal.project.local@ and @cabal.project.freeze@ which are also
@@ -51,7 +52,7 @@ projectFlagsOptions showOrParseArgs =
         flagProjectDir (\path flags -> flags { flagProjectDir = path })
         (reqArg "DIR" (succeedReadE Flag) flagToList)
     , option [] ["project-file"]
-        "Set the path of the cabal.project file (relative to the project directory)"
+        "Set the path of the cabal.project file (relative to the project directory when relative)"
         flagProjectFile (\pf flags -> flags { flagProjectFile = pf })
         (reqArg "FILE" (succeedReadE Flag) flagToList)
     , option ['z'] ["ignore-project"]

cabal-install/tests/UnitTests/Distribution/Client/ProjectConfig.hs

@@ -59,12 +59,12 @@ import Distribution.Client.ProjectConfig.Legacy
 
 import UnitTests.Distribution.Client.ArbitraryInstances
 import UnitTests.Distribution.Client.TreeDiffInstances ()
-import Test.Tasty
-import Test.Tasty.HUnit
-import Test.Tasty.QuickCheck
 
 import Data.TreeDiff.Class
 import Data.TreeDiff.QuickCheck
+import Test.Tasty
+import Test.Tasty.HUnit
+import Test.Tasty.QuickCheck
 
 tests :: [TestTree]
 tests =
@@ -108,34 +108,35 @@ tests =
 
 testFindProjectRoot :: TestTree
 testFindProjectRoot = testGroup "findProjectRoot"
-  [ test "defaults"                         (cd dir)    Nothing    Nothing               (succeeds dir file)
-  , test "defaults in lib"                  (cd libDir) Nothing    Nothing               (succeeds dir file)
+  [ test "defaults"                         (cd dir)    Nothing    Nothing          (succeeds dir file)
+  , test "defaults in lib"                  (cd libDir) Nothing    Nothing          (succeeds dir file)
 
-  , test "explicit file"                    (cd dir)    Nothing    (Just file)           (succeeds dir file)
-  , test "explicit file in lib"             (cd libDir) Nothing    (Just file)           (succeeds dir file)
+  , test "explicit file"                    (cd dir)    Nothing    (Just file)      (succeeds dir file)
+  , test "explicit file in lib"             (cd libDir) Nothing    (Just file)      (succeeds dir file)
 
-  , test "other file"                       (cd dir)    Nothing    (Just fileOther)      (succeeds dir fileOther)
-  , test "other file in lib"                (cd libDir) Nothing    (Just fileOther)      (succeeds dir fileOther)
+  , test "other file"                       (cd dir)    Nothing    (Just fileOther) (succeeds dir fileOther)
+  , test "other file in lib"                (cd libDir) Nothing    (Just fileOther) (succeeds dir fileOther)
 
   -- Deprecated use-case
-  , test "absolute file"                    Nothing     Nothing    (Just (dir </> file)) (succeeds dir file)
+  , test "absolute file"                    Nothing     Nothing    (Just absFile)   (succeeds dir file)
 
-  , test "nested file"                      (cd dir)    Nothing    (Just nixFile)        (succeeds dir nixFile)
-  , test "nested file in lib"               (cd libDir) Nothing    (Just nixFile)        (succeeds dir nixFile)
+  , test "nested file"                      (cd dir)    Nothing    (Just nixFile)   (succeeds dir nixFile)
+  , test "nested file in lib"               (cd libDir) Nothing    (Just nixFile)   (succeeds dir nixFile)
 
-  , test "explicit dir"                     Nothing     (Just dir) Nothing               (succeeds dir file)
-  , test "explicit dir & file"              Nothing     (Just dir) (Just file)           (succeeds dir file)
-  , test "explicit dir & nested file"       Nothing     (Just dir) (Just nixFile)        (succeeds dir nixFile)
-  , test "explicit dir & nested other file" Nothing     (Just dir) (Just nixOther)       (succeeds dir nixOther)
+  , test "explicit dir"                     Nothing     (Just dir) Nothing          (succeeds dir file)
+  , test "explicit dir & file"              Nothing     (Just dir) (Just file)      (succeeds dir file)
+  , test "explicit dir & nested file"       Nothing     (Just dir) (Just nixFile)   (succeeds dir nixFile)
+  , test "explicit dir & nested other file" Nothing     (Just dir) (Just nixOther)  (succeeds dir nixOther)
 
-  , test "explicit dir & absolute file"     Nothing     (Just dir) (Just (dir </> file)) fails
+  , test "explicit dir & absolute file"     Nothing     (Just dir) (Just absFile)   (succeedsWith ProjectRootExplicitAbsolute dir absFile)
   ]
   where
     dir    = fixturesDir </> "project-root"
     libDir = dir </> "lib"
 
     file      = defaultProjectFile
     fileOther = file <.> "other"
+    absFile   = dir </> file
 
     nixFile   = "nix" </> file
     nixOther  = nixFile <.> "other"
@@ -158,9 +159,11 @@ testFindProjectRoot = testGroup "findProjectRoot"
 
     cd d = Just (withCurrentDirectory d)
 
-    succeeds projectDir projectFile result = case result of
+    succeeds = succeedsWith ProjectRootExplicit
+
+    succeedsWith mk projectDir projectFile result = case result of
       Left err -> assertFailure $ "Expected ProjectRoot, but found " <> show err
-      Right pr -> pr @?= ProjectRootExplicit projectDir projectFile
+      Right pr -> pr @?= mk projectDir projectFile
 
     fails result = case result of
       Left _  -> pure ()

changelog.d/pr-8454

@@ -7,6 +7,6 @@ significance: significant
 description: {
 
 - Added --project-dir flag for specifying the project's root directory
-- Deprecated using --project-file with an absolute filepath
+- Deprecated using --project-file with an absolute filepath without also using --project-dir
 
 }

doc/cabal-project.rst

@@ -286,9 +286,11 @@ package, and thus apply globally:
 .. _cmdoption-project-dir:
 .. option:: --project-dir=DIR
 
-    Specifies the path of the project directory.
-    When :ref:`project-file<cmdoption-project-file>` is also specified, it is
-    relative to this directory.
+    Specifies the path of the project directory. If a relative
+    :ref:`project-file<cmdoption-project-file>` path is also specified,
+    it will be resolved relative to this directory.
+
+    The project directory need not contain a ``cabal.project`` file.
 
     This option cannot be specified via a ``cabal.project`` file.
 
@@ -303,7 +305,8 @@ package, and thus apply globally:
     ``--project-file=my.project``, then the other files that will
     be probed are ``my.project.freeze`` and ``my.project.local``.
 
-    If :ref:`project-dir<cmdoption-project-dir>` is not specified, we will
+    If :ref:`project-dir<cmdoption-project-dir>` is not specified,
+    and the path is relative, we will
     look for the file relative to the current working directory,
     and then for the parent directory, until the project file is
     found or we have hit the top of the user's home directory.