caret operator accepts a set of versions

Cabal/Cabal.cabal

@@ -73,6 +73,14 @@ extra-source-files:
   tests/ParserTests/errors/spdx-2.errors
   tests/ParserTests/errors/spdx-3.cabal
   tests/ParserTests/errors/spdx-3.errors
+  tests/ParserTests/errors/version-sets-1.cabal
+  tests/ParserTests/errors/version-sets-1.errors
+  tests/ParserTests/errors/version-sets-2.cabal
+  tests/ParserTests/errors/version-sets-2.errors
+  tests/ParserTests/errors/version-sets-3.cabal
+  tests/ParserTests/errors/version-sets-3.errors
+  tests/ParserTests/errors/version-sets-4.cabal
+  tests/ParserTests/errors/version-sets-4.errors
   tests/ParserTests/ipi/Includes2.cabal
   tests/ParserTests/ipi/Includes2.expr
   tests/ParserTests/ipi/Includes2.format
@@ -172,6 +180,9 @@ extra-source-files:
   tests/ParserTests/regressions/th-lift-instances.cabal
   tests/ParserTests/regressions/th-lift-instances.expr
   tests/ParserTests/regressions/th-lift-instances.format
+  tests/ParserTests/regressions/version-sets.cabal
+  tests/ParserTests/regressions/version-sets.expr
+  tests/ParserTests/regressions/version-sets.format
   tests/ParserTests/regressions/wl-pprint-indef.cabal
   tests/ParserTests/regressions/wl-pprint-indef.expr
   tests/ParserTests/regressions/wl-pprint-indef.format

Cabal/ChangeLog.md

@@ -1,5 +1,6 @@
 # 2.6.0.0 (current development version)
   * TODO
+  * Introduce set notation for `^>=` and `==` operators.
   * 'check' reports warnings for various ghc-\*-options fields separately
     ([#5342](https://github.com/haskell/cabal/issues/5432)).
   * `KnownExtension`: added new extension `DerivingVia`.

Cabal/Distribution/Types/VersionRange.hs

@@ -420,8 +420,19 @@ instance Parsec VersionRange where
 
                 "==" -> do
                     P.spaces
-                    (wild, v) <- verOrWild
-                    pure $ (if wild then withinVersion else thisVersion) v
+                    (do (wild, v) <- verOrWild
+                        pure $ (if wild then withinVersion else thisVersion) v
+                     <|>
+                     (verSet' thisVersion =<< verSet))
+
+                "^>=" -> do
+                    P.spaces
+                    (do (wild, v) <- verOrWild
+                        when wild $ P.unexpected $
+                            "wild-card version after ^>= operator"
+                        majorBoundVersion' v
+                     <|>
+                     (verSet' majorBoundVersion =<< verSet))
 
                 _ -> do
                     P.spaces
@@ -431,7 +442,6 @@ instance Parsec VersionRange where
                     case op of
                         ">="  -> pure $ orLaterVersion v
                         "<"   -> pure $ earlierVersion v
-                        "^>=" -> majorBoundVersion' v
                         "<="  -> pure $ orEarlierVersion v
                         ">"   -> pure $ laterVersion v
                         _ -> fail $ "Unknown version operator " ++ show op
@@ -469,6 +479,34 @@ instance Parsec VersionRange where
                 (orLaterVersion u) (earlierVersion (majorUpperBound u))
             embed vr = embedVersionRange vr
 
+        -- version set notation (e.g. "== { 0.0.1.0, 0.0.2.0, 0.1.0.0 }")
+        verSet' op vs = do
+            csv <- askCabalSpecVersion
+            if csv >= CabalSpecV3_0
+            then pure $ foldr1 unionVersionRanges (map op vs)
+            else fail $ unwords
+                [ "version set syntax used."
+                , "To use this syntax the package needs to specify at least 'cabal-version: 3.0'."
+                , "Alternatively, if broader compatibility is important then use"
+                , "a series of single version constraints joined with the || operator:"
+                , prettyShow (foldr1 unionVersionRanges (map op vs))
+                ]
+
+        verSet :: CabalParsing m => m [Version]
+        verSet = do
+            _ <- P.char '{'
+            P.spaces
+            vs <- P.sepBy1 (verPlain <* P.spaces) (P.char ',' *> P.spaces)
+            _ <- P.char '}'
+            pure vs
+
+        -- a plain version without tags or wildcards
+        -- note: this uses P.integral which allows redundant zeros.
+        --   This is not a problem because 'verPlain' is only used by
+        --   'verSet' which requires cabal > 3
+        verPlain :: CabalParsing m => m Version
+        verPlain = mkVersion <$> P.sepBy1 P.integral (P.char '.')
+
         -- either wildcard or normal version
         verOrWild :: CabalParsing m => m (Bool, Version)
         verOrWild = do

Cabal/doc/developing-packages.rst

@@ -2134,6 +2134,25 @@ system-dependent values for these fields.
        renaming in ``build-depends``; however, this support has since been
        removed and should not be used.
 
+    Starting with Cabal 3.0, a set notation for the ``==`` and ``^>=`` operator
+    is available. For instance,
+
+    ::
+
+        tested-with: GHC == 8.6.3, GHC == 8.4.4, GHC == 8.2.2, GHC == 8.0.2,
+                     GHC == 7.10.3, GHC == 7.8.4, GHC == 7.6.3, GHC == 7.4.2
+
+        build-depends: network ^>= 2.6.3.6 || ^>= 2.7.0.2 || ^>= 2.8.0.0 || ^>= 3.0.1.0
+
+    can be then written in a more convenient and concise form
+
+    ::
+
+        tested-with: GHC == { 8.6.3, 8.4.4, 8.2.2, 8.0.2, 7.10.3, 7.8.4, 7.6.3, 7.4.2 }
+
+        build-depends: network ^>= { 2.6.3.6, 2.7.0.2, 2.8.0.0, 3.0.1.0 }
+
+
 .. pkg-field:: other-modules: identifier list
 
     A list of modules used by the component but not exposed to users.

Cabal/tests/ParserTests.hs

@@ -112,6 +112,10 @@ errorTests = testGroup "errors"
     , errorTest "spdx-2.cabal"
     , errorTest "spdx-3.cabal"
     , errorTest "removed-fields.cabal"
+    , errorTest "version-sets-1.cabal"
+    , errorTest "version-sets-2.cabal"
+    , errorTest "version-sets-3.cabal"
+    , errorTest "version-sets-4.cabal"
     ]
 
 errorTest :: FilePath -> TestTree
@@ -159,6 +163,7 @@ regressionTests = testGroup "regressions"
     , regressionTest "spdx-3.cabal"
     , regressionTest "hidden-main-lib.cabal"
     , regressionTest "jaeger-flamegraph.cabal"
+    , regressionTest "version-sets.cabal"
     ]
 
 regressionTest :: FilePath -> TestTree

Cabal/tests/ParserTests/errors/version-sets-1.cabal

@@ -0,0 +1,8 @@
+cabal-version:       2.5
+name:                version-sets
+version:             0
+synopsis:            version set notation
+
+library
+  default-language: Haskell2010
+  build-depends: network == { }

Cabal/tests/ParserTests/errors/version-sets-1.errors

@@ -0,0 +1,5 @@
+VERSION: Just (mkVersion [2,5])
+version-sets-1.cabal:8:31: 
+unexpected "}"
+expecting space or integral
+

Cabal/tests/ParserTests/errors/version-sets-2.cabal

@@ -0,0 +1,8 @@
+cabal-version:       2.5
+name:                version-sets
+version:             0
+synopsis:            version set notation
+
+library
+  default-language: Haskell2010
+  build-depends: network >= { 2.8.0.0 }

Cabal/tests/ParserTests/errors/version-sets-2.errors

@@ -0,0 +1,5 @@
+VERSION: Just (mkVersion [2,5])
+version-sets-2.cabal:8:29: 
+unexpected "{"
+expecting space or integral
+

Cabal/tests/ParserTests/errors/version-sets-3.cabal

@@ -0,0 +1,8 @@
+cabal-version:       2.5
+name:                version-sets
+version:             0
+synopsis:            version set notation
+
+library
+  default-language: Haskell2010
+  build-depends: network == { 2.8.0.0, }

Cabal/tests/ParserTests/errors/version-sets-3.errors

@@ -0,0 +1,5 @@
+VERSION: Just (mkVersion [2,5])
+version-sets-3.cabal:8:40: 
+unexpected "}"
+expecting space or integral
+

Cabal/tests/ParserTests/errors/version-sets-4.cabal

@@ -0,0 +1,8 @@
+cabal-version:       2.5
+name:                version-sets
+version:             0
+synopsis:            version set notation
+
+library
+  default-language: Haskell2010
+  build-depends: network == { 2.8.* }

Cabal/tests/ParserTests/errors/version-sets-4.errors

@@ -0,0 +1,5 @@
+VERSION: Just (mkVersion [2,5])
+version-sets-4.cabal:8:35: 
+unexpected "*"
+expecting integral
+

Cabal/tests/ParserTests/regressions/version-sets.cabal

@@ -0,0 +1,18 @@
+cabal-version:       2.5
+name:                version-sets
+version:             0
+synopsis:            version set notation
+tested-with: GHC == { 8.6.3, 8.4.4, 8.2.2, 8.0.2, 7.10.3, 7.8.4, 7.6.3, 7.4.2 }
+
+library
+  default-language: Haskell2010
+  build-depends: network ^>= {0}
+  build-depends: base == {1}, base == { 1 }, base == {1,2}, base == {1.2}, base == {1.2,3.4}
+  build-depends: ghc == {
+    8.6.3
+    ,
+    8.4.4    ,8.2.2     ,
+    8.0.2,7.10.3
+    , 7.8.4, 7.6.3, 7.4.2
+    }
+  build-depends: Cabal ^>= { 2.4.1.1, 2.2.0.0 }