Allow arrays of contract types as type expressions e.g. for abi.decode.

test/libsolidity/syntaxTests/array/contract_index_access.sol

@@ -0,0 +1,8 @@
+contract C {
+    function f() view public {
+        C[0];
+    }
+}
+// ----
+// Warning 6133: (52-56): Statement has no effect.
+// Warning 2018: (17-63): Function state mutability can be restricted to pure

test/libsolidity/syntaxTests/array/invalid/contract_index_access.sol

@@ -1,7 +0,0 @@
-contract C {
-    function f() view public {
-        C[0];
-    }
-}
-// ----
-// TypeError 2876: (52-56): Index access for contracts or libraries is not possible.

test/libsolidity/syntaxTests/array/invalid/library_index_access.sol

@@ -4,4 +4,4 @@ library C {
     }
 }
 // ----
-// TypeError 2876: (51-55): Index access for contracts or libraries is not possible.
+// TypeError 2876: (51-55): Index access for library types and arrays of libraries are not possible.

test/libsolidity/syntaxTests/indexing/index_range_access_assert.sol

@@ -3,4 +3,3 @@ contract s{}
 function f() {s[:][];}
 // ----
 // TypeError 1760: (53-57): Types cannot be sliced.
-// TypeError 2876: (53-59): Index access for contracts or libraries is not possible.

test/libsolidity/syntaxTests/specialFunctions/abidecode/contract_array.sol

@@ -0,0 +1,5 @@
+contract C {
+	function f(bytes calldata x) public pure returns (C[] memory c) {
+		c = abi.decode(x, (C[]));
+	}
+}