Fix detection of recursive structs.

4 files changed, 36 insertions, 0 deletions

diff --git a/Changelog.md b/Changelog.md
index 70e98751..63c99144 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -16,6 +16,7 @@ Bugfixes:
  * Commandline interface: Support ``--evm-version constantinople`` properly.
  * DocString Parser: Fix error message for empty descriptions.
  * Standard JSON: Support ``constantinople`` as ``evmVersion`` properly.
+ * Type Checker: Fix detection of recursive structs.
  * Type System: Improve error message when attempting to shift by a fractional amount.
  * Type System: Make external library functions accessible.
  * Type System: Prevent encoding of weird types.
diff --git a/libsolidity/ast/Types.cpp b/libsolidity/ast/Types.cpp
index 42fd1c3d..42f6b5ca 100644
--- a/libsolidity/ast/Types.cpp
+++ b/libsolidity/ast/Types.cpp
@@ -1972,9 +1972,12 @@ bool StructType::recursive() const
 	if (!m_recursive.is_initialized())
 	{
 		set<StructDefinition const*> structsSeen;
+		set<StructDefinition const*> structsProcessed;
 		function<bool(StructType const*)> check = [&](StructType const* t) -> bool
 		{
 			StructDefinition const* str = &t->structDefinition();
+			if (structsProcessed.count(str))
+				return false;
 			if (structsSeen.count(str))
 				return true;
 			structsSeen.insert(str);
@@ -1987,6 +1990,8 @@ bool StructType::recursive() const
 					if (check(innerStruct))
 						return true;
 			}
+			structsSeen.erase(str);
+			structsProcessed.insert(str);
 			return false;
 		};
 		m_recursive = check(this);
diff --git a/test/libsolidity/syntaxTests/structs/recursion/multi_struct_composition.sol b/test/libsolidity/syntaxTests/structs/recursion/multi_struct_composition.sol
new file mode 100644
index 00000000..9a1c22f1
--- /dev/null
+++ b/test/libsolidity/syntaxTests/structs/recursion/multi_struct_composition.sol
@@ -0,0 +1,15 @@
+pragma experimental ABIEncoderV2;
+
+contract C {
+  struct T { U u; V v; }
+
+  struct U { W w; }
+
+  struct V { W w; }
+
+  struct W { uint x; }
+
+  function f(T) public pure { }
+}
+// ----
+// Warning: Experimental features are turned on. Do not use experimental features on live deployments.
diff --git a/test/libsolidity/syntaxTests/structs/recursion/parallel_structs.sol b/test/libsolidity/syntaxTests/structs/recursion/parallel_structs.sol
new file mode 100644
index 00000000..d4ad088d
--- /dev/null
+++ b/test/libsolidity/syntaxTests/structs/recursion/parallel_structs.sol
@@ -0,0 +1,15 @@
+pragma experimental ABIEncoderV2;
+
+contract TestContract
+{
+    struct SubStruct {
+        uint256 id;
+    }
+    struct TestStruct {
+        SubStruct subStruct1;
+        SubStruct subStruct2;
+    }
+    function addTestStruct(TestStruct) public pure {}
+}
+// ----
+// Warning: Experimental features are turned on. Do not use experimental features on live deployments.