Expose constraints that apply to any setup dependency.

For example, "setup.Cabal installed" forces cabal to use the installed Cabal
library for all setup scripts.

Cabal/doc/installing-packages.rst

@@ -1321,9 +1321,14 @@ Miscellaneous options
 
     ::
 
-        # Example use of the 'setup' qualifier. This constraint
-        # applies to package bar when it is a dependency of the
-        # Setup.hs script of package foo.
+        # Example uses of 'setup' qualifiers.
+
+        # This constraint applies to package bar when it is a
+        # dependency of any Setup.hs script.
+        $ cabal install --constraint="setup.bar == 1.0"
+
+        # This constraint applies to package bar when it is a
+        # dependency of the Setup.hs script of package foo.
         $ cabal install --constraint="foo:setup.bar == 1.0"
 
     ..  TODO: Uncomment this example once we decide on a syntax for 'exe'.

cabal-install/Distribution/Client/Targets.hs

@@ -719,6 +719,9 @@ data UserConstraintScope =
   -- | Scope that applies to the package when it has the specified qualifier.
   UserQualified UserQualifier PackageName
 
+  -- | Scope that applies to the package when it has a setup qualifier.
+  | UserAnySetupQualifier PackageName
+
   -- | Scope that applies to the package when it has any qualifier.
   | UserAnyQualifier PackageName
   deriving (Eq, Show, Generic)
@@ -733,6 +736,7 @@ fromUserQualifier (UserQualExe name1 name2) = QualExe name1 name2
 fromUserConstraintScope :: UserConstraintScope -> ConstraintScope
 fromUserConstraintScope (UserQualified q pn) =
     ScopeQualified (fromUserQualifier q) pn
+fromUserConstraintScope (UserAnySetupQualifier pn) = ScopeAnySetupQualifier pn
 fromUserConstraintScope (UserAnyQualifier pn) = ScopeAnyQualifier pn
 
 -- | Version of 'PackageConstraint' that the user can specify on
@@ -748,6 +752,7 @@ userConstraintPackageName (UserConstraint scope _) = scopePN scope
   where
     scopePN (UserQualified _ pn) = pn
     scopePN (UserAnyQualifier pn) = pn
+    scopePN (UserAnySetupQualifier pn) = pn
 
 userToPackageConstraint :: UserConstraint -> PackageConstraint
 userToPackageConstraint (UserConstraint scope prop) =
@@ -776,6 +781,11 @@ instance Text UserConstraint where
              pn <- parse
              return (UserAnyQualifier pn)
           +++
+          do
+             _ <- Parse.string "setup."
+             pn <- parse
+             return (UserAnySetupQualifier pn)
+          +++
           do
              -- Qualified name
              pn <- parse

cabal-install/changelog

@@ -37,8 +37,9 @@
 	* New 'cabal-install' command: 'outdated', for listing outdated
 	version bounds in a .cabal file or a freeze file (#4207).
 	* Added qualified constraints for setup dependencies. For example,
-	--constraint="foo:setup.bar == 1.0" constrains foo's setup dependency
-	on bar (part of #3502).
+	--constraint="setup.bar == 1.0" constrains all setup dependencies on
+	bar, and --constraint="foo:setup.bar == 1.0" constrains foo's setup
+	dependency on bar (part of #3502).
 	* Non-qualified constraints, such as --constraint="bar == 1.0", now
 	only apply to top-level dependencies. They don't constrain setup or
 	build-tool dependencies. The new syntax --constraint="any.bar == 1.0"

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

@@ -567,6 +567,7 @@ instance Arbitrary RemoteRepo where
 
 instance Arbitrary UserConstraintScope where
     arbitrary = oneof [ UserQualified <$> arbitrary <*> arbitrary
+                      , UserAnySetupQualifier <$> arbitrary
                       , UserAnyQualifier <$> arbitrary
                       ]
 

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

@@ -58,6 +58,10 @@ exampleConstraints =
      UserConstraint (UserAnyQualifier (pn "directory"))
                     (PackagePropertyStanzas [TestStanzas]))
 
+  , ("setup.Cabal installed",
+     UserConstraint (UserAnySetupQualifier (pn "Cabal"))
+                    PackagePropertyInstalled)
+
   , ("process:setup.bytestring ==5.2",
      UserConstraint (UserQualified (UserQualSetup (pn "process")) (pn "bytestring"))
                     (PackagePropertyVersion (thisVersion (mkVersion [5, 2]))))