caret / pvp operator accepts a set of versions. For example

  build-depends: network ^>= { 2.6.3.6, 2.7.0.2, 2.8.0.0, 3.0.1.0 }

Author: tseenshe

Cabal/ChangeLog.md

@@ -1,5 +1,6 @@
 # 2.6.0.0 (current development version)
   * TODO
+  * `^>=` takes multiple parameters
   * '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 +479,31 @@ 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 '{'
+            vs <- P.sepBy1 (P.spaces *> verPlain) (P.try (P.spaces *> P.char ','))
+            P.spaces
+            _ <- P.char '}'
+            pure vs
+
+        -- plain version without tags or wildcards
+        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.