Merge pull request #9990 from ethereum/issue-4751

Print warning for unnamed return parameters and no return statement

Changelog.md

@@ -6,6 +6,8 @@ Language Features:
 
 Compiler Features:
  * SMTChecker: Support inline arrays.
+ * Control Flow Graph: Print warning for non-empty functions with unnamed return parameters that are not assigned a value in all code paths.
+
 
 Bugfixes:
  * Code generator: Fix internal compiler error when referencing members via module name but not using the reference.

docs/contracts/functions.rst

@@ -424,6 +424,8 @@ operations as long as there is enough gas passed on to it.
             // If someone sends Ether to that contract, the receive function in TestPayable will be called.
             require(address(test).send(2 ether));
             // results in test.x becoming == 2 and test.y becoming 2 ether.
+
+            return true;
         }
     }
 

libsolidity/analysis/ControlFlowAnalyzer.cpp

@@ -37,13 +37,13 @@ bool ControlFlowAnalyzer::visit(FunctionDefinition const& _function)
 	if (_function.isImplemented())
 	{
 		auto const& functionFlow = m_cfg.functionFlow(_function);
-		checkUninitializedAccess(functionFlow.entry, functionFlow.exit);
+		checkUninitializedAccess(functionFlow.entry, functionFlow.exit, _function.body().statements().empty());
 		checkUnreachable(functionFlow.entry, functionFlow.exit, functionFlow.revert, functionFlow.transactionReturn);
 	}
 	return false;
 }
 
-void ControlFlowAnalyzer::checkUninitializedAccess(CFGNode const* _entry, CFGNode const* _exit) const
+void ControlFlowAnalyzer::checkUninitializedAccess(CFGNode const* _entry, CFGNode const* _exit, bool _emptyBody) const
 {
 	struct NodeInfo
 	{
@@ -95,14 +95,10 @@ void ControlFlowAnalyzer::checkUninitializedAccess(CFGNode const* _entry, CFGNod
 				case VariableOccurrence::Kind::Return:
 					if (unassignedVariables.count(&variableOccurrence.declaration()))
 					{
-						if (
-							variableOccurrence.declaration().type()->dataStoredIn(DataLocation::Storage) ||
-							variableOccurrence.declaration().type()->dataStoredIn(DataLocation::CallData)
-						)
-							// Merely store the unassigned access. We do not generate an error right away, since this
-							// path might still always revert. It is only an error if this is propagated to the exit
-							// node of the function (i.e. there is a path with an uninitialized access).
-							nodeInfo.uninitializedVariableAccesses.insert(&variableOccurrence);
+						// Merely store the unassigned access. We do not generate an error right away, since this
+						// path might still always revert. It is only an error if this is propagated to the exit
+						// node of the function (i.e. there is a path with an uninitialized access).
+						nodeInfo.uninitializedVariableAccesses.insert(&variableOccurrence);
 					}
 					break;
 				case VariableOccurrence::Kind::Declaration:
@@ -140,18 +136,26 @@ void ControlFlowAnalyzer::checkUninitializedAccess(CFGNode const* _entry, CFGNod
 				ssl.append("The variable was declared here.", variableOccurrence->declaration().location());
 
 			bool isStorage = variableOccurrence->declaration().type()->dataStoredIn(DataLocation::Storage);
-			m_errorReporter.typeError(
-				3464_error,
-				variableOccurrence->occurrence() ?
-					*variableOccurrence->occurrence() :
+			bool isCalldata = variableOccurrence->declaration().type()->dataStoredIn(DataLocation::CallData);
+			if (isStorage || isCalldata)
+				m_errorReporter.typeError(
+					3464_error,
+					variableOccurrence->occurrence() ?
+						*variableOccurrence->occurrence() :
+						variableOccurrence->declaration().location(),
+					ssl,
+					"This variable is of " +
+					string(isStorage ? "storage" : "calldata") +
+					" pointer type and can be " +
+					(variableOccurrence->kind() == VariableOccurrence::Kind::Return ? "returned" : "accessed") +
+					" without prior assignment, which would lead to undefined behaviour."
+				);
+			else if (!_emptyBody && variableOccurrence->declaration().name().empty())
+				m_errorReporter.warning(
+					6321_error,
 					variableOccurrence->declaration().location(),
-				ssl,
-				"This variable is of " +
-				string(isStorage ? "storage" : "calldata") +
-				" pointer type and can be " +
-				(variableOccurrence->kind() == VariableOccurrence::Kind::Return ? "returned" : "accessed") +
-				" without prior assignment, which would lead to undefined behaviour."
-			);
+					"Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable."
+				);
 		}
 	}
 }

libsolidity/analysis/ControlFlowAnalyzer.h

@@ -36,7 +36,7 @@ public:
 
 private:
 	/// Checks for uninitialized variable accesses in the control flow between @param _entry and @param _exit.
-	void checkUninitializedAccess(CFGNode const* _entry, CFGNode const* _exit) const;
+	void checkUninitializedAccess(CFGNode const* _entry, CFGNode const* _exit, bool _emptyBody) const;
 	/// Checks for unreachable code, i.e. code ending in @param _exit, @param _revert or @param _transactionReturn
 	/// that can not be reached from @param _entry.
 	void checkUnreachable(CFGNode const* _entry, CFGNode const* _exit, CFGNode const* _revert, CFGNode const* _transactionReturn) const;

test/cmdlineTests/optimizer_array_sload/input.sol

@@ -4,8 +4,8 @@ pragma solidity >=0.0;
 contract Arraysum {
 	uint256[] values;
 
-	function sumArray() public view returns(uint) {
-		uint sum = 0;
+	function sumArray() public view returns(uint sum) {
+		sum = 0;
 		// The optimizer should read the length of the array only once, because
 		// LoopInvariantCodeMotion can move the `sload` corresponding to the length outside of the
 		// loop.

test/cmdlineTests/optimizer_array_sload/output

@@ -43,7 +43,7 @@ object "Arraysum_33" {
                             vloc_sum := add(vloc_sum, _3)
                         }
                         let memPos := allocateMemory(_1)
-                        return(memPos, sub(abi_encode_uint(memPos, _1), memPos))
+                        return(memPos, sub(abi_encode_uint(memPos, vloc_sum), memPos))
                     }
                 }
                 revert(0, 0)

test/libsolidity/smtCheckerTests/complex/warn_on_struct.sol

@@ -7,6 +7,7 @@ contract C {
     }
 }
 // ----
+// Warning 6321: (117-121): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
 // Warning 2072: (133-143): Unused local variable.
 // Warning 8364: (146-147): Assertion checker does not yet implement type type(struct C.A storage pointer)
 // Warning 4639: (146-163): Assertion checker does not yet implement this expression.

test/libsolidity/smtCheckerTests/control_flow/require.sol

@@ -30,4 +30,5 @@ contract C {
 	}
 }
 // ----
+// Warning 6321: (429-442): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
 // Warning 6328: (448-465): CHC: Assertion violation happens here.

test/libsolidity/smtCheckerTests/control_flow/revert.sol

@@ -32,4 +32,5 @@ contract C {
 // ----
 // Warning 5740: (116-129): Unreachable code.
 // Warning 5740: (221-234): Unreachable code.
+// Warning 6321: (408-421): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
 // Warning 6328: (427-444): CHC: Assertion violation happens here.

test/libsolidity/smtCheckerTests/control_flow/try_catch_1.sol

@@ -8,5 +8,6 @@ contract C {
 // ====
 // EVMVersion: >=byzantium
 // ----
+// Warning 6321: (75-79): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
 // Warning 7645: (98-121): Assertion checker does not support try/catch clauses.
 // Warning 7645: (124-159): Assertion checker does not support try/catch clauses.

test/libsolidity/smtCheckerTests/functions/function_external_call_should_not_inline_1.sol

@@ -13,3 +13,4 @@ contract C {
 	}
 }
 // ----
+// Warning 6321: (85-89): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.

test/libsolidity/smtCheckerTests/functions/internal_call_state_var_init_2.sol

@@ -7,3 +7,4 @@ contract c {
 	bool b = (f() > 0) || (f() > 0);
 }
 // ----
+// Warning 6321: (86-90): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.

test/libsolidity/smtCheckerTests/functions/recursive_multi_return.sol

@@ -9,3 +9,5 @@ contract C {
 }
 //
 // ----
+// Warning 6321: (81-85): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
+// Warning 6321: (87-91): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.

test/libsolidity/smtCheckerTests/functions/recursive_multi_return_2.sol

@@ -23,5 +23,18 @@ a;
 	}
 }
 // ----
+// Warning 6321: (163-167): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
+// Warning 6321: (171-175): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
+// Warning 6321: (179-183): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
+// Warning 6321: (187-191): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
+// Warning 6321: (195-199): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
+// Warning 6321: (203-207): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
+// Warning 6321: (211-215): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
+// Warning 6321: (219-223): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
+// Warning 6321: (227-231): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
+// Warning 6321: (235-239): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
+// Warning 6321: (241-244): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
+// Warning 6321: (246-250): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
+// Warning 6321: (252-259): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
 // Warning 6133: (72-90): Statement has no effect.
 // Warning 6133: (96-107): Statement has no effect.

test/libsolidity/smtCheckerTests/math/addmod_mulmod_zero.sol

@@ -21,6 +21,7 @@ contract C {
 	}
 }
 // ----
+// Warning 6321: (253-260): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
 // Warning 1218: (94-109): CHC: Error trying to invoke SMT solver.
 // Warning 1218: (113-126): CHC: Error trying to invoke SMT solver.
 // Warning 1218: (180-195): CHC: Error trying to invoke SMT solver.

test/libsolidity/smtCheckerTests/operators/compound_bitwise_and_fixed_bytes.sol

@@ -11,4 +11,5 @@ contract C {
     }
 }
 // ----
+// Warning 6321: (83-87): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
 // Warning 6328: (203-217): CHC: Assertion violation happens here.

test/libsolidity/smtCheckerTests/operators/compound_bitwise_or_fixed_bytes.sol

@@ -11,4 +11,5 @@ contract C {
     }
 }
 // ----
+// Warning 6321: (83-87): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
 // Warning 6328: (203-217): CHC: Assertion violation happens here.

test/libsolidity/smtCheckerTests/operators/compound_bitwise_xor_fixed_bytes.sol

@@ -11,4 +11,5 @@ contract C {
     }
 }
 // ----
+// Warning 6321: (83-87): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
 // Warning 6328: (204-221): CHC: Assertion violation happens here.

test/libsolidity/smtCheckerTests/overflow/overflow_sum_signed.sol

@@ -14,6 +14,7 @@ contract C
 	}
 }
 // ----
+// Warning 6321: (87-91): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
 // Warning 4984: (117-122): CHC: Overflow (resulting value larger than 127) happens here.
 // Warning 4984: (151-158): CHC: Overflow (resulting value larger than 127) happens here.
 // Warning 3944: (197-205): CHC: Underflow (resulting value less than -128) happens here.

test/libsolidity/smtCheckerTests/special/event.sol

@@ -25,4 +25,6 @@ contract C {
 	}
 }
 // ----
+// Warning 6321: (280-284): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
+// Warning 6321: (430-434): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
 // Warning 6328: (440-449): CHC: Assertion violation happens here.

test/libsolidity/smtCheckerTests/special/log.sol

@@ -36,4 +36,5 @@ contract C {
 	}
 }
 // ----
+// Warning 6321: (655-662): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
 // Warning 6328: (668-677): CHC: Assertion violation happens here.

test/libsolidity/smtCheckerTests/types/no_effect_statements.sol

@@ -10,6 +10,7 @@ contract test {
     }
 }
 // ----
+// Warning 6321: (115-119): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
 // Warning 6133: (125-126): Statement has no effect.
 // Warning 6133: (130-136): Statement has no effect.
 // Warning 6133: (140-144): Statement has no effect.

test/libsolidity/smtCheckerTests/types/rational_large_1.sol

@@ -7,4 +7,5 @@ contract c {
 	}
 }
 // ----
+// Warning 6321: (80-84): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
 // Warning 6328: (128-142): CHC: Assertion violation happens here.

test/libsolidity/smtCheckerTests/types/tuple_different_count_assignment_1.sol

@@ -8,4 +8,5 @@ contract C {
 	}
 }
 // ----
+// Warning 6321: (79-82): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
 // Warning 6328: (157-171): CHC: Assertion violation happens here.

test/libsolidity/smtCheckerTests/types/tuple_different_count_assignment_2.sol

@@ -8,4 +8,5 @@ contract C {
 	}
 }
 // ----
+// Warning 6321: (79-82): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
 // Warning 6328: (159-173): CHC: Assertion violation happens here.

test/libsolidity/smtCheckerTests/types/tuple_extra_parens_1.sol

@@ -5,3 +5,5 @@ contract C {
 		((, a)) = (1, 2);
 	}
 }
+// ----
+// Warning 6321: (80-83): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.

test/libsolidity/smtCheckerTests/types/tuple_extra_parens_2.sol

@@ -5,3 +5,5 @@ contract C {
 		(((, a),)) = ((1, 2), 3);
 	}
 }
+// ----
+// Warning 6321: (80-83): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.

test/libsolidity/smtCheckerTests/types/tuple_extra_parens_3.sol

@@ -5,3 +5,5 @@ contract C {
 		(((((((, a),)))))) = ((1, 2), 3);
 	}
 }
+// ----
+// Warning 6321: (80-83): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.

test/libsolidity/smtCheckerTests/types/tuple_extra_parens_4.sol

@@ -5,3 +5,5 @@ contract C {
 		((((((, a)))),)) = ((1, 2), 3);
 	}
 }
+// ----
+// Warning 6321: (80-83): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.

test/libsolidity/smtCheckerTests/types/tuple_extra_parens_5.sol

@@ -5,3 +5,5 @@ contract C {
 		((((((((((((, a))))))),))))) = ((1, 2), 3);
 	}
 }
+// ----
+// Warning 6321: (80-83): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.

test/libsolidity/syntaxTests/abiEncoder/v2_accessing_returned_dynamic_array_with_returndata_support.sol

@@ -10,4 +10,5 @@ contract C {
 // ====
 // EVMVersion: >=byzantium
 // ----
+// Warning 6321: (150-154): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
 // Warning 2072: (166-183): Unused local variable.

test/libsolidity/syntaxTests/controlFlow/storageReturn/default_location.sol

@@ -17,3 +17,4 @@ contract C {
     }
 }
 // ----
+// Warning 6321: (399-407): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.

test/libsolidity/syntaxTests/dataLocations/function_return_parameters_with_data_location_fine.sol

@@ -4,3 +4,6 @@ contract C {
     function h() public pure returns(uint[] memory) {}
     function i() external pure returns(uint[] memory) {}
 }
+// ----
+// Warning 6321: (51-64): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
+// Warning 6321: (134-147): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.

test/libsolidity/syntaxTests/freeFunctions/qualified_struct_access.sol

@@ -4,4 +4,5 @@ contract C {
     struct S { uint x; }
 }
 // ----
+// Warning 6321: (22-26): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
 // TypeError 3464: (45-46): This variable is of storage pointer type and can be accessed without prior assignment, which would lead to undefined behaviour.

test/libsolidity/syntaxTests/metaTypes/typeOfContract.sol

@@ -4,4 +4,5 @@ contract Test {
     }
 }
 // ----
+// Warning 6321: (54-66): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
 // Warning 6133: (78-88): Statement has no effect.

test/libsolidity/syntaxTests/multiVariableDeclaration/multiSingleVariableDeclaration.sol

@@ -4,3 +4,5 @@ contract C {
     a;
   }
 }
+// ----
+// Warning 6321: (46-50): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.

test/libsolidity/syntaxTests/multiVariableDeclaration/multiVariableDeclarationComplex.sol

@@ -9,3 +9,7 @@ contract C {
   function g() internal pure returns (uint, uint, uint, D.S[20] storage x, uint) { x = x; }
 }
 // ----
+// Warning 6321: (176-180): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
+// Warning 6321: (182-186): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
+// Warning 6321: (188-192): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
+// Warning 6321: (213-217): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.

test/libsolidity/syntaxTests/multiVariableDeclaration/multiVariableDeclarationSimple.sol

@@ -10,3 +10,8 @@ contract C {
   function h() internal pure returns (bytes memory, string storage s) { s = s; }
 }
 // ----
+// Warning 6321: (51-55): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
+// Warning 6321: (57-61): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
+// Warning 6321: (63-67): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
+// Warning 6321: (69-73): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
+// Warning 6321: (250-262): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.

test/libsolidity/syntaxTests/nameAndTypeResolution/018_forward_function_reference.sol

@@ -8,3 +8,5 @@ contract Second {
         if (First(2).fun() == true) return 1;
     }
 }
+// ----
+// Warning 6321: (183-187): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.

test/libsolidity/syntaxTests/nameAndTypeResolution/no_effect_statements.sol

@@ -9,6 +9,7 @@ contract test {
     }
 }
 // ----
+// Warning 6321: (83-87): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
 // Warning 6133: (93-94): Statement has no effect.
 // Warning 6133: (98-104): Statement has no effect.
 // Warning 6133: (108-112): Statement has no effect.

test/libsolidity/syntaxTests/parsing/address_payable_function_type.sol

@@ -4,3 +4,5 @@ contract C {
         function (address payable) payable external returns (address payable) h; h;
     }
 }
+// ----
+// Warning 6321: (197-267): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.

test/libsolidity/syntaxTests/parsing/if_statement.sol

@@ -4,5 +4,6 @@ contract test {
     }
 }
 // ----
+// Warning 6321: (60-64): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
 // Warning 2072: (109-115): Unused local variable.
 // Warning 2018: (20-128): Function state mutability can be restricted to pure

test/libsolidity/syntaxTests/tryCatch/almost_call_options.sol

@@ -11,4 +11,6 @@ contract C {
 // ====
 // EVMVersion: >=byzantium
 // ----
+// Warning 6321: (73-77): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
+// Warning 6321: (79-83): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
 // Warning 2072: (122-134): Unused local variable.

test/libsolidity/syntaxTests/tryCatch/catch_error.sol

@@ -9,3 +9,6 @@ contract C {
 }
 // ====
 // EVMVersion: >=byzantium
+// ----
+// Warning 6321: (46-50): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
+// Warning 6321: (52-56): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.

test/libsolidity/syntaxTests/tryCatch/catch_error_named.sol

@@ -9,3 +9,6 @@ contract C {
 }
 // ====
 // EVMVersion: >=byzantium
+// ----
+// Warning 6321: (46-50): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
+// Warning 6321: (52-56): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.

test/libsolidity/syntaxTests/tryCatch/catch_low_level.sol

@@ -9,3 +9,6 @@ contract C {
 }
 // ====
 // EVMVersion: >=byzantium
+// ----
+// Warning 6321: (46-50): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
+// Warning 6321: (52-56): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.

test/libsolidity/syntaxTests/tryCatch/no_returns.sol

@@ -7,3 +7,6 @@ contract C {
         }
     }
 }
+// ----
+// Warning 6321: (46-50): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
+// Warning 6321: (52-56): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.

test/libsolidity/syntaxTests/tryCatch/returns.sol

@@ -8,3 +8,6 @@ contract C {
         }
     }
 }
+// ----
+// Warning 6321: (46-50): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
+// Warning 6321: (52-56): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.

test/libsolidity/syntaxTests/tryCatch/returns_memory.sol

@@ -9,3 +9,6 @@ contract C {
 }
 // ====
 // EVMVersion: >=byzantium
+// ----
+// Warning 6321: (46-59): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
+// Warning 6321: (61-65): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.

test/libsolidity/syntaxTests/tryCatch/returns_memory_anonymous.sol

@@ -9,3 +9,6 @@ contract C {
 }
 // ====
 // EVMVersion: >=byzantium
+// ----
+// Warning 6321: (46-59): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
+// Warning 6321: (61-65): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.

test/libsolidity/syntaxTests/tryCatch/two_catch_clauses.sol

@@ -12,3 +12,6 @@ contract C {
 }
 // ====
 // EVMVersion: >=byzantium
+// ----
+// Warning 6321: (46-50): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
+// Warning 6321: (52-56): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.

test/libsolidity/syntaxTests/tupleAssignments/large_component_count.sol

@@ -21,3 +21,6 @@ contract C {
 	}
 }
 // ----
+// Warning 6321: (194-198): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
+// Warning 6321: (200-204): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.
+// Warning 6321: (206-213): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.

test/libsolidity/syntaxTests/types/function_types/selector/local_variable_selector_not_pure.sol

@@ -6,3 +6,5 @@ contract C {
         g.selector;
     }
 }
+// ----
+// Warning 6321: (51-57): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.

test/libsolidity/syntaxTests/viewPureChecker/call_internal_functions_success.sol

@@ -4,3 +4,5 @@ contract C {
     function h() public { h(); g(); f(); }
     function i() payable public { i(); h(); g(); f(); }
 }
+// ----
+// Warning 6321: (89-93): Unnamed return variable can remain unassigned. Add an explicit return with value to all non-reverting code paths or name the variable.