Extract recursive struct tests.

test/libsolidity/syntaxTests/structs/recursion/return_recursive_structs.sol

@@ -0,0 +1,7 @@
+contract C {
+    struct S { uint a; S[] sub; }
+    function f() public pure returns (uint, S) {
+    }
+}
+// ----
+// TypeError: Internal or recursive type is not allowed for public or external functions.

test/libsolidity/syntaxTests/structs/recursion/return_recursive_structs2.sol

@@ -0,0 +1,7 @@
+contract C {
+    struct S { uint a; S[2][] sub; }
+    function f() public pure returns (uint, S) {
+    }
+}
+// ----
+// TypeError: Internal or recursive type is not allowed for public or external functions.

test/libsolidity/syntaxTests/structs/recursion/return_recursive_structs3.sol

@@ -0,0 +1,8 @@
+contract C {
+    struct S { uint a; S[][][] sub; }
+    struct T { S s; }
+    function f() public pure returns (uint x, T t) {
+    }
+}
+// ----
+// TypeError: Internal or recursive type is not allowed for public or external functions.

test/libsolidity/syntaxTests/structs/recursion/struct_definition_directly_recursive.sol

@@ -0,0 +1,8 @@
+contract Test {
+    struct MyStructName {
+        address addr;
+        MyStructName x;
+    }
+}
+// ----
+// TypeError: Recursive struct definition.

test/libsolidity/syntaxTests/structs/recursion/struct_definition_indirectly_recursive.sol

@@ -0,0 +1,12 @@
+contract Test {
+    struct MyStructName1 {
+        address addr;
+        uint256 count;
+        MyStructName2 x;
+    }
+    struct MyStructName2 {
+        MyStructName1 x;
+    }
+}
+// ----
+// TypeError: Recursive struct definition.

test/libsolidity/syntaxTests/structs/recursion/struct_definition_not_really_recursive.sol

@@ -0,0 +1,4 @@
+contract Test {
+    struct S1 { uint a; }
+    struct S2 { S1 x; S1 y; }
+}

test/libsolidity/syntaxTests/structs/recursion/struct_definition_recursion_via_mapping.sol

@@ -0,0 +1,7 @@
+contract Test {
+    struct MyStructName1 {
+        address addr;
+        uint256 count;
+        mapping(uint => MyStructName1) x;
+    }
+}