Type Checker: skip zero-param free functions in attachedFunctions resolution

libsolidity/ast/Types.cpp

@@ -457,10 +457,16 @@ MemberList::MemberMap Type::attachedFunctions(Type const& _type, ASTNode const&
 				}
 			}
 			else
-				addFunction(
-					dynamic_cast<FunctionDefinition const&>(*declaration),
-					identifierPath->path().back()
-				);
+			{
+				auto const& functionDefinition = dynamic_cast<FunctionDefinition const&>(*declaration);
+				// Zero-parameter functions are rejected by TypeChecker::endVisit(UsingForDirective)
+				// with error 4731, but member resolution can run before the directive is visited
+				// when the call site precedes the directive in the contract body. Skip these here
+				// so addFunction() does not assert in withBoundFirstArgument() (#16610).
+				if (functionDefinition.parameters().empty())
+					continue;
+				addFunction(functionDefinition, identifierPath->path().back());
+			}
 		}
 
 	return members;

test/libsolidity/syntaxTests/using/using_free_no_parameters_call_site_before_directive.sol

@@ -0,0 +1,11 @@
+function zero() pure returns (uint) { return 0; }
+
+contract C {
+    function f(uint z) pure external returns (uint) {
+        return z.zero();
+    }
+    using {zero} for uint;
+}
+// ----
+// TypeError 9582: (133-139): Member "zero" not found or not visible after argument-dependent lookup in uint256.
+// TypeError 4731: (160-164): The function "zero" does not have any parameters, and therefore cannot be attached to the type "uint256".