Require cabal.project packages and/or optional-packages field

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

@@ -9,6 +9,7 @@ module Distribution.Client.DistDirLayout
     DistDirLayout (..)
   , DistDirParams (..)
   , defaultDistDirLayout
+  , distProjectFileMain
 
     -- * 'ProjectRoot'
   , ProjectRoot (..)
@@ -316,3 +317,8 @@ mkCabalDirLayout mstoreDir mlogDir = do
   cabalLogsDirectory <-
     maybe defaultLogsDir pure mlogDir
   pure $ CabalDirLayout{..}
+
+-- | Given the 'DistDirLayout''s distProjectFile function, returns the
+-- main project file (i.e. cabal.project).
+distProjectFileMain :: (String -> FilePath) -> FilePath
+distProjectFileMain f = f ""

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

@@ -192,6 +192,7 @@ data CabalInstallException
   | LegacyAndParsecParseResultsDiffer FilePath String String
   | CabalFileParseFailure CabalFileParseError
   | ProjectConfigParseFailure ProjectConfigParseError
+  | ProjectConfigNoPackages FilePath
   deriving (Show)
 
 exceptionCodeCabalInstall :: CabalInstallException -> Int
@@ -348,6 +349,7 @@ exceptionCodeCabalInstall e = case e of
   LegacyAndParsecParseResultsDiffer{} -> 7165
   CabalFileParseFailure{} -> 7166
   ProjectConfigParseFailure{} -> 7167
+  ProjectConfigNoPackages{} -> 7168
 
 exceptionMessageCabalInstall :: CabalInstallException -> String
 exceptionMessageCabalInstall e = case e of
@@ -885,6 +887,13 @@ exceptionMessageCabalInstall e = case e of
     renderCabalFileParseError cbfError
   ProjectConfigParseFailure pcfError ->
     renderProjectConfigParseError pcfError
+  ProjectConfigNoPackages configPath ->
+    concat
+      [ "The project config '"
+      , configPath
+      , "' requires at least one of the fields 'packages' "
+      , "or 'optional-packages', but neither was specified."
+      ]
 
 instance Exception (VerboseException CabalInstallException) where
   displayException :: VerboseException CabalInstallException -> [Char]

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

@@ -307,8 +307,10 @@ establishProjectBaseContextWithRoot verbosity cliConfig projectRoot currentComma
           projectConfig
 
   -- https://github.com/haskell/cabal/issues/6013
+  -- https://github.com/haskell/cabal/issues/7401
+  let projPath = distProjectFileMain (distProjectFile distDirLayout)
   when (null (projectPackages projectConfig) && null (projectPackagesOptional projectConfig)) $
-    warn verbosity "There are no packages or optional-packages in the project"
+    dieWithException verbosity (ProjectConfigNoPackages projPath)
 
   return
     ProjectBaseContext

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

@@ -379,7 +379,7 @@ rebuildProjectConfig
       configPath <- getConfigFilePath verbosity projectConfigConfigFile
       return
         ( configPath
-        , distProjectFile ""
+        , distProjectFileMain distProjectFile
         , (projectConfigHcFlavor, projectConfigHcPath, projectConfigHcPkg)
         , projectConfigProjectFileParser
         , progsearchpath

cabal-install/tests/fixtures/configure/cabal.project

@@ -1,2 +1,4 @@
 ignore-project: False
 optimization: 2
+
+packages: .

cabal-install/tests/fixtures/configure/dummy.cabal

@@ -0,0 +1,17 @@
+cabal-version: 3.0
+
+-- Required by ./cabal.project, due to cabal.project requiring a valid
+-- packages or optional-packages field.
+
+name: main
+version: 0.1
+build-type: Simple
+category: Test
+maintainer: Dummy
+synopsis: Dummy
+description: Dummy
+license: BSD-3-Clause
+
+library
+  build-depends: base
+  default-language: Haskell2010

cabal-testsuite/PackageTests/ProjectPackages/Empty/cabal.out

@@ -0,0 +1,11 @@
+# cabal v2-build
+Error: [Cabal-7136]
+There is no <pkgname>.cabal package file or cabal.project file. To build packages locally you need at minimum a <pkgname>.cabal file. You can use 'cabal init' to create one.
+
+For non-trivial projects you will also want a cabal.project file in the root directory of your project. This file lists the packages in your project and all other build configuration. See the Cabal user guide for full details.
+
+# cabal v2-build
+Error: [Cabal-7136]
+There is no <pkgname>.cabal package file or cabal.project file. To build packages locally you need at minimum a <pkgname>.cabal file. You can use 'cabal init' to create one.
+
+For non-trivial projects you will also want a cabal.project file in the root directory of your project. This file lists the packages in your project and all other build configuration. See the Cabal user guide for full details.

cabal-testsuite/PackageTests/ProjectPackages/Empty/cabal.test.hs

@@ -0,0 +1,5 @@
+import Test.Cabal.Prelude
+
+main = cabalTest $ do
+  fails $ cabal "v2-build" ["--dry-run"]
+  fails $ cabal "v2-build" ["--dry-run", "all"]

cabal-testsuite/PackageTests/ProjectPackages/FieldNoCabal/cabal.out

@@ -0,0 +1,2 @@
+# cabal v2-build
+# cabal v2-build

cabal-testsuite/PackageTests/ProjectPackages/FieldNoCabal/cabal.project

@@ -0,0 +1 @@
+packages: .

cabal-testsuite/PackageTests/ProjectPackages/FieldNoCabal/cabal.test.hs

@@ -0,0 +1,9 @@
+import Test.Cabal.Prelude
+
+main = cabalTest $ do
+  let expected = "- The package directory '.' does not contain any .cabal file."
+  r1 <- fails $ cabal' "v2-build" ["--dry-run"]
+  assertOutputContains expected r1
+
+  r2 <- fails $ cabal' "v2-build" ["--dry-run", "all"]
+  assertOutputContains expected r2

cabal-testsuite/PackageTests/ProjectPackages/MultiLocalField/cabal.out

@@ -0,0 +1,10 @@
+# cabal v2-build
+Resolving dependencies...
+Build profile: -w ghc-<GHCVER> -O1
+In order, the following would be built:
+ - main-0.1 (lib) (first run)
+
+# cabal v2-build
+Build profile: -w ghc-<GHCVER> -O1
+In order, the following would be built:
+ - main-0.1 (lib) (first run)

cabal-testsuite/PackageTests/ProjectPackages/MultiLocalField/cabal.project

@@ -0,0 +1 @@
+-- empty

cabal-testsuite/PackageTests/ProjectPackages/MultiLocalField/cabal.project.local

@@ -0,0 +1 @@
+packages: .

cabal-testsuite/PackageTests/ProjectPackages/MultiLocalField/cabal.test.hs

@@ -0,0 +1,5 @@
+import Test.Cabal.Prelude
+
+main = cabalTest $ do
+  cabal "v2-build" ["--dry-run"]
+  cabal "v2-build" ["--dry-run", "all"]

cabal-testsuite/PackageTests/ProjectPackages/MultiLocalField/main.cabal

@@ -0,0 +1,14 @@
+cabal-version: 3.0
+
+name: main
+version: 0.1
+build-type: Simple
+category: Test
+maintainer: Joe
+synopsis: Test input
+description: Test input
+license: BSD-3-Clause
+
+library
+  build-depends: base
+  default-language: Haskell2010

cabal-testsuite/PackageTests/ProjectPackages/MultiNoField/cabal.out

@@ -0,0 +1,7 @@
+# cabal v2-build
+Error: [Cabal-7168]
+The project config '<ROOT>/cabal.project' requires at least one of the fields 'packages' or 'optional-packages', but neither was specified.
+
+# cabal v2-build
+Error: [Cabal-7168]
+The project config '<ROOT>/cabal.project' requires at least one of the fields 'packages' or 'optional-packages', but neither was specified.

cabal-testsuite/PackageTests/ProjectPackages/MultiNoField/cabal.project

@@ -0,0 +1 @@
+-- empty

cabal-testsuite/PackageTests/ProjectPackages/MultiNoField/cabal.project.local

@@ -0,0 +1 @@
+-- empty

cabal-testsuite/PackageTests/ProjectPackages/MultiNoField/cabal.test.hs

@@ -0,0 +1,5 @@
+import Test.Cabal.Prelude
+
+main = cabalTest $ do
+  fails $ cabal "v2-build" ["--dry-run"]
+  fails $ cabal "v2-build" ["--dry-run", "all"]

cabal-testsuite/PackageTests/ProjectPackages/MultiNoField/main.cabal

@@ -0,0 +1,14 @@
+cabal-version: 3.0
+
+name: main
+version: 0.1
+build-type: Simple
+category: Test
+maintainer: Joe
+synopsis: Test input
+description: Test input
+license: BSD-3-Clause
+
+library
+  build-depends: base
+  default-language: Haskell2010

cabal-testsuite/PackageTests/ProjectPackages/NoField/cabal.out

@@ -0,0 +1,7 @@
+# cabal v2-build
+Error: [Cabal-7168]
+The project config '<ROOT>/cabal.project' requires at least one of the fields 'packages' or 'optional-packages', but neither was specified.
+
+# cabal v2-build
+Error: [Cabal-7168]
+The project config '<ROOT>/cabal.project' requires at least one of the fields 'packages' or 'optional-packages', but neither was specified.

cabal-testsuite/PackageTests/ProjectPackages/NoField/cabal.project

@@ -0,0 +1 @@
+-- empty

cabal-testsuite/PackageTests/ProjectPackages/NoField/cabal.test.hs

@@ -0,0 +1,5 @@
+import Test.Cabal.Prelude
+
+main = cabalTest $ do
+  fails $ cabal "v2-build" ["--dry-run"]
+  fails $ cabal "v2-build" ["--dry-run", "all"]

cabal-testsuite/PackageTests/ProjectPackages/NoField/main.cabal

@@ -0,0 +1,14 @@
+cabal-version: 3.0
+
+name: main
+version: 0.1
+build-type: Simple
+category: Test
+maintainer: Joe
+synopsis: Test input
+description: Test input
+license: BSD-3-Clause
+
+library
+  build-depends: base
+  default-language: Haskell2010

cabal-testsuite/PackageTests/ProjectPackages/NoFieldNoCabal/cabal.out

@@ -0,0 +1,7 @@
+# cabal v2-build
+Error: [Cabal-7168]
+The project config '<ROOT>/cabal.project' requires at least one of the fields 'packages' or 'optional-packages', but neither was specified.
+
+# cabal v2-build
+Error: [Cabal-7168]
+The project config '<ROOT>/cabal.project' requires at least one of the fields 'packages' or 'optional-packages', but neither was specified.

cabal-testsuite/PackageTests/ProjectPackages/NoFieldNoCabal/cabal.project

@@ -0,0 +1 @@
+-- empty

cabal-testsuite/PackageTests/ProjectPackages/NoFieldNoCabal/cabal.test.hs

@@ -0,0 +1,5 @@
+import Test.Cabal.Prelude
+
+main = cabalTest $ do
+  fails $ cabal "v2-build" ["--dry-run"]
+  fails $ cabal "v2-build" ["--dry-run", "all"]

cabal-testsuite/PackageTests/ProjectPackages/OtherNoField/cabal.out

@@ -0,0 +1,7 @@
+# cabal v2-build
+Error: [Cabal-7168]
+The project config '<ROOT>/dir/cabal.project' requires at least one of the fields 'packages' or 'optional-packages', but neither was specified.
+
+# cabal v2-build
+Error: [Cabal-7168]
+The project config '<ROOT>/dir/cabal.project' requires at least one of the fields 'packages' or 'optional-packages', but neither was specified.

cabal-testsuite/PackageTests/ProjectPackages/OtherNoField/cabal.test.hs

@@ -0,0 +1,5 @@
+import Test.Cabal.Prelude
+
+main = cabalTest $ do
+  fails $ cabal "v2-build" ["--dry-run", "--project-file", "dir/cabal.project"]
+  fails $ cabal "v2-build" ["--dry-run", "--project-file", "dir/cabal.project", "all"]

cabal-testsuite/PackageTests/ProjectPackages/OtherNoField/dir/cabal.project

@@ -0,0 +1 @@
+-- empty

cabal-testsuite/PackageTests/ProjectPackages/OtherNoField/main.cabal

@@ -0,0 +1,14 @@
+cabal-version: 3.0
+
+name: main
+version: 0.1
+build-type: Simple
+category: Test
+maintainer: Joe
+synopsis: Test input
+description: Test input
+license: BSD-3-Clause
+
+library
+  build-depends: base
+  default-language: Haskell2010

cabal-testsuite/PackageTests/ProjectPackages/ParentNoField/cabal.out

@@ -0,0 +1,9 @@
+# cabal v2-build
+Configuration is affected by cabal.project at '<GBLTMPDIR>'.
+Error: [Cabal-7168]
+The project config '<ROOT>/cabal.project' requires at least one of the fields 'packages' or 'optional-packages', but neither was specified.
+
+# cabal v2-build
+Configuration is affected by cabal.project at '<GBLTMPDIR>'.
+Error: [Cabal-7168]
+The project config '<ROOT>/cabal.project' requires at least one of the fields 'packages' or 'optional-packages', but neither was specified.

cabal-testsuite/PackageTests/ProjectPackages/ParentNoField/cabal.project

@@ -0,0 +1 @@
+-- empty

cabal-testsuite/PackageTests/ProjectPackages/ParentNoField/cabal.test.hs

@@ -0,0 +1,5 @@
+import Test.Cabal.Prelude
+
+main = cabalTest $ withDirectory "./dir" $ do
+  fails $ cabal "v2-build" ["--dry-run"]
+  fails $ cabal "v2-build" ["--dry-run", "all"]

cabal-testsuite/PackageTests/ProjectPackages/ParentNoField/dir/main.cabal

@@ -0,0 +1,14 @@
+cabal-version: 3.0
+
+name: main
+version: 0.1
+build-type: Simple
+category: Test
+maintainer: Joe
+synopsis: Test input
+description: Test input
+license: BSD-3-Clause
+
+library
+  build-depends: base
+  default-language: Haskell2010

cabal-testsuite/PackageTests/ReplProjectTargetTwoPkgs/cabal.out

@@ -26,9 +26,8 @@ Please pick a single [package:][ctype:]component (or all) as target for the REPL
  - pkg-two
 # checking repl command with an 'empty.project' with no packages
 # cabal repl
-Warning: There are no packages or optional-packages in the project
-Error: [Cabal-7076]
-There are no packages in 'empty.project'. Please add a package to the project and pick a single [package:][ctype:]component (or all) as target for the REPL command.
+Error: [Cabal-7168]
+The project config '<ROOT>/empty.project' requires at least one of the fields 'packages' or 'optional-packages', but neither was specified.
 # checking repl command with a missing 'missing.project'
 # cabal repl
 # checking repl command with a missing 'missing.project'

changelog.d/pr-11574

@@ -0,0 +1,20 @@
+synopsis: Require cabal.project packages and/or optional-packages field.
+packages: cabal-install
+prs: #11574
+issues: #7401
+significance:
+
+description: {
+
+Currently, if a cabal.project file is present and the `packages` and
+`optional-packages` fields do not exist, a warning will be issued, and
+cabal will fail with a different, potentially misleading error message:
+
+  "There is no <pkgname>.cabal package file or cabal.project file..."
+
+This changes it so that the prior warning is now an error, hence will cause
+cabal to fail before the misleading error is given. That at least one of
+these fields is required is already specified in the docs, hence this is not
+a specification change.
+
+}