Fix shadowing struct types by struct member names

Author: a3d4

libsolidity/analysis/NameAndTypeResolver.cpp

@@ -191,6 +191,21 @@ Declaration const* NameAndTypeResolver::pathFromCurrentScope(vector<ASTString> c
 {
 	solAssert(!_path.empty(), "");
 	vector<Declaration const*> candidates = m_currentScope->resolveName(_path.front(), true);
+
+	if (!candidates.empty() && candidates.front()->isStructMember())
+	{
+		// A special case like
+		// enum E {a}; struct S {E E;}
+		// We are within a struct scope and resolved name is a struct member name.
+		// We resolve again, starting from the enclosing scope now.
+		solAssert(_path.size() == 1, "");
+		solAssert(candidates.size() == 1, "");
+		DeclarationContainer const* enclosingContainer = m_currentScope->enclosingContainer();
+		if (!enclosingContainer)
+			return nullptr;
+		candidates = enclosingContainer->resolveName(_path.front(), true);
+	}
+
 	for (size_t i = 1; i < _path.size() && candidates.size() == 1; i++)
 	{
 		if (!m_scopes.count(candidates.front()))

test/libsolidity/syntaxTests/structs/member_type_eq_name.sol

@@ -3,4 +3,4 @@ contract C {
   function f(function(S memory) external) public {}
 }
 // ----
-// TypeError 5172: (25-26): Name has to refer to a struct, enum or contract.
+// DeclarationError 7920: (25-26): Identifier not found or not unique.

test/libsolidity/syntaxTests/structs/member_type_eq_name_2.sol

@@ -0,0 +1,6 @@
+contract C {
+    enum E {a, b, c}
+    struct S {E X; uint E;}
+    struct T {E T; uint E;}
+    struct U {E E;}
+}