Merge pull request #12628 from nishant-sachdeva/adding_functiontype_string_and_allow_string_concat_operations

Added support for FunctionType::Kind::StringConcat

Changelog.md

@@ -17,6 +17,7 @@ Bugfixes:
  * Code Generator: Fix ICE when accessing the members of external functions occupying more than two stack slots.
  * Code Generator: Fix ICE when doing an explicit conversion from ``string calldata`` to ``bytes``.
  * Control Flow Graph: Perform proper virtual lookup for modifiers for uninitialized variable and unreachable code analysis.
+ * General: ``string.concat`` now properly takes strings as arguments and returns ``string memory``. It was accidentally introduced as a copy of ``bytes.concat`` before.
  * Immutables: Fix wrong error when the constructor of a base contract uses ``return`` and the derived contract contains immutable variables.
  * IR Generator: Add missing cleanup during the conversion of fixed bytes types to smaller fixed bytes types.
  * IR Generator: Add missing cleanup for indexed event arguments of value type.

docs/cheatsheet.rst

@@ -86,6 +86,8 @@ Global Variables
   to ``abi.encodeWithSelector(bytes4(keccak256(bytes(signature)), ...)``
 - ``bytes.concat(...) returns (bytes memory)``: :ref:`Concatenates variable number of
   arguments to one byte array<bytes-concat>`
+- ``string.concat(...) returns (string memory)``: :ref:`Concatenates variable number of
+  arguments to one string array<string-concat>`
 - ``block.basefee`` (``uint``): current block's base fee (`EIP-3198 <https://eips.ethereum.org/EIPS/eip-3198>`_ and `EIP-1559 <https://eips.ethereum.org/EIPS/eip-1559>`_)
 - ``block.chainid`` (``uint``): current chain id
 - ``block.coinbase`` (``address payable``): current block miner's address

docs/types/reference-types.rst

@@ -150,7 +150,7 @@ length or index access.
 Solidity does not have string manipulation functions, but there are
 third-party string libraries. You can also compare two strings by their keccak256-hash using
 ``keccak256(abi.encodePacked(s1)) == keccak256(abi.encodePacked(s2))`` and
-concatenate two strings using ``bytes.concat(bytes(s1), bytes(s2))``.
+concatenate two strings using ``string.concat(s1, s2)``.
 
 You should use ``bytes`` over ``bytes1[]`` because it is cheaper,
 since using ``bytes1[]`` in ``memory`` adds 31 padding bytes between the elements. Note that in ``storage``, the
@@ -165,31 +165,40 @@ always use one of the value types ``bytes1`` to ``bytes32`` because they are muc
     that you are accessing the low-level bytes of the UTF-8 representation,
     and not the individual characters.
 
-.. index:: ! bytes-concat
+.. index:: ! bytes-concat, ! string-concat
 
 .. _bytes-concat:
+.. _string-concat:
 
-``bytes.concat`` function
+The functions ``bytes.concat`` and ``string.concat``
-^^^^^^^^^^^^^^^^^^^^^^^^^
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-You can concatenate a variable number of ``bytes`` or ``bytes1 ... bytes32`` using ``bytes.concat``.
+You can concatenate an arbitrary number of ``string`` values using ``string.concat``.
+The function returns a single ``string memory`` array that contains the contents of the arguments without padding.
+If you want to use parameters of other types that are not implicitly convertible to ``string``, you need to convert them to ``string`` first.
+
+Analogously, the ``bytes.concat`` function can concatenate an arbitrary number of ``bytes`` or ``bytes1 ... bytes32`` values.
 The function returns a single ``bytes memory`` array that contains the contents of the arguments without padding.
-If you want to use string parameters or other types, you need to convert them to ``bytes`` or ``bytes1``/.../``bytes32`` first.
+If you want to use string parameters or other types that are not implicitly convertible to ``bytes``, you need to convert them to ``bytes`` or ``bytes1``/.../``bytes32`` first.
+
 
 .. code-block:: solidity
 
     // SPDX-License-Identifier: GPL-3.0
-    pragma solidity ^0.8.4;
+    pragma solidity ^0.8.12;
 
     contract C {
-        bytes s = "Storage";
+        string s = "Storage";
-        function f(bytes calldata c, string memory m, bytes16 b) public view {
+        function f(bytes calldata bc, string memory sm, bytes16 b) public view {
-            bytes memory a = bytes.concat(s, c, c[:2], "Literal", bytes(m), b);
+            string memory concat_string = string.concat(s, string(bc), "Literal", sm);
-            assert((s.length + c.length + 2 + 7 + bytes(m).length + 16) == a.length);
+            assert((bytes(s).length + bc.length + 7 + bytes(sm).length) == bytes(concat_string).length);
+
+            bytes memory concat_bytes = bytes.concat(bytes(s), bc, bc[:2], "Literal", bytes(sm), b);
+            assert((bytes(s).length + bc.length + 2 + 7 + bytes(sm).length + b.length) == concat_bytes.length);
         }
     }
 
-If you call ``bytes.concat`` without arguments it will return an empty ``bytes`` array.
+If you call ``string.concat`` or ``bytes.concat`` without arguments they return an empty array.
 
 .. index:: ! array;allocating, new
 

docs/units-and-global-variables.rst

@@ -154,6 +154,14 @@ Members of bytes
 
 - ``bytes.concat(...) returns (bytes memory)``: :ref:`Concatenates variable number of bytes and bytes1, ..., bytes32 arguments to one byte array<bytes-concat>`
 
+.. index:: string members
+
+Members of string
+-----------------
+
+- ``string.concat(...) returns (string memory)``: :ref:`Concatenates variable number of string arguments to one string array<string-concat>`
+
+
 .. index:: assert, revert, require
 
 Error Handling

libsolidity/analysis/TypeChecker.cpp

@@ -2207,14 +2207,42 @@ void TypeChecker::typeCheckABIEncodeCallFunction(FunctionCall const& _functionCa
 	}
 }
 
+
+void TypeChecker::typeCheckStringConcatFunction(
+	FunctionCall const& _functionCall,
+	FunctionType const* _functionType
+)
+{
+	solAssert(_functionType);
+	solAssert(_functionType->kind() == FunctionType::Kind::StringConcat);
+	solAssert(_functionCall.names().empty());
+
+	typeCheckFunctionGeneralChecks(_functionCall, _functionType);
+
+	for (shared_ptr<Expression const> const& argument: _functionCall.arguments())
+	{
+		Type const* argumentType = type(*argument);
+		bool notConvertibleToString = !argumentType->isImplicitlyConvertibleTo(*TypeProvider::stringMemory());
+
+		if (notConvertibleToString)
+			m_errorReporter.typeError(
+				9977_error,
+				argument->location(),
+				"Invalid type for argument in the string.concat function call. "
+				"string type is required, but " +
+				argumentType->identifier() + " provided."
+			);
+	}
+}
+
 void TypeChecker::typeCheckBytesConcatFunction(
 	FunctionCall const& _functionCall,
 	FunctionType const* _functionType
 )
 {
-	solAssert(_functionType, "");
+	solAssert(_functionType);
-	solAssert(_functionType->kind() == FunctionType::Kind::BytesConcat, "");
+	solAssert(_functionType->kind() == FunctionType::Kind::BytesConcat);
-	solAssert(_functionCall.names().empty(), "");
+	solAssert(_functionCall.names().empty());
 
 	typeCheckFunctionGeneralChecks(_functionCall, _functionType);
 
@@ -2651,6 +2679,12 @@ bool TypeChecker::visit(FunctionCall const& _functionCall)
 			returnTypes = functionType->returnParameterTypes();
 			break;
 		}
+		case FunctionType::Kind::StringConcat:
+		{
+			typeCheckStringConcatFunction(_functionCall, functionType);
+			returnTypes = functionType->returnParameterTypes();
+			break;
+		}
 		case FunctionType::Kind::Wrap:
 		case FunctionType::Kind::Unwrap:
 		{

libsolidity/analysis/TypeChecker.h

@@ -113,6 +113,12 @@ private:
 	/// Performs checks specific to the ABI encode functions of type ABIEncodeCall
 	void typeCheckABIEncodeCallFunction(FunctionCall const& _functionCall);
 
+	/// Performs general checks and checks specific to string concat function call
+	void typeCheckStringConcatFunction(
+		FunctionCall const& _functionCall,
+		FunctionType const* _functionType
+	);
+
 	/// Performs general checks and checks specific to bytes concat function call
 	void typeCheckBytesConcatFunction(
 		FunctionCall const& _functionCall,

libsolidity/ast/Types.cpp

@@ -2928,6 +2928,7 @@ string FunctionType::richIdentifier() const
 	case Kind::ArrayPush: id += "arraypush"; break;
 	case Kind::ArrayPop: id += "arraypop"; break;
 	case Kind::BytesConcat: id += "bytesconcat"; break;
+	case Kind::StringConcat: id += "stringconcat"; break;
 	case Kind::ObjectCreation: id += "objectcreation"; break;
 	case Kind::Assert: id += "assert"; break;
 	case Kind::Require: id += "require"; break;
@@ -3817,15 +3818,14 @@ MemberList::MemberMap TypeType::nativeMembers(ASTNode const* _currentScope) cons
 	)
 		members.emplace_back("concat", TypeProvider::function(
 			TypePointers{},
-			TypePointers{TypeProvider::bytesMemory()},
+			TypePointers{arrayType->isString() ? TypeProvider::stringMemory() : TypeProvider::bytesMemory()},
 			strings{},
-			strings{string()},
+			strings{string{}},
-			FunctionType::Kind::BytesConcat,
+			arrayType->isString() ? FunctionType::Kind::StringConcat : FunctionType::Kind::BytesConcat,
 			StateMutability::Pure,
 			nullptr,
 			FunctionType::Options::withArbitraryParameters()
 		));
-
 	return members;
 }
 

libsolidity/ast/Types.h

@@ -1228,6 +1228,7 @@ public:
 		ArrayPush, ///< .push() to a dynamically sized array in storage
 		ArrayPop, ///< .pop() from a dynamically sized array in storage
 		BytesConcat, ///< .concat() on bytes (type type)
+		StringConcat, ///< .concat() on string (type type)
 		ObjectCreation, ///< array creation using new
 		Assert, ///< assert()
 		Require, ///< require()

libsolidity/codegen/ExpressionCompiler.cpp

@@ -1101,6 +1101,7 @@ bool ExpressionCompiler::visit(FunctionCall const& _functionCall)
 			ArrayUtils(m_context).popStorageArrayElement(*arrayType);
 			break;
 		}
+		case FunctionType::Kind::StringConcat:
 		case FunctionType::Kind::BytesConcat:
 		{
 			_functionCall.expression().accept(*this);
@@ -1121,8 +1122,16 @@ bool ExpressionCompiler::visit(FunctionCall const& _functionCall)
 				else
 				{
 					solAssert(!dynamic_cast<RationalNumberType const*>(argument->annotation().type), "");
-					solAssert(argument->annotation().type->isImplicitlyConvertibleTo(*TypeProvider::bytesMemory()), "");
+					if (function.kind() == FunctionType::Kind::StringConcat)
-					targetTypes.emplace_back(TypeProvider::bytesMemory());
+					{
+						solAssert(argument->annotation().type->isImplicitlyConvertibleTo(*TypeProvider::stringMemory()), "");
+						targetTypes.emplace_back(TypeProvider::stringMemory());
+					}
+					else if (function.kind() == FunctionType::Kind::BytesConcat)
+					{
+						solAssert(argument->annotation().type->isImplicitlyConvertibleTo(*TypeProvider::bytesMemory()), "");
+						targetTypes.emplace_back(TypeProvider::bytesMemory());
+					}
 				}
 			}
 			utils().fetchFreeMemoryPointer();

libsolidity/codegen/YulUtilFunctions.cpp

@@ -2475,18 +2475,26 @@ string YulUtilFunctions::copyArrayFromStorageToMemoryFunction(ArrayType const& _
 	});
 }
 
-string YulUtilFunctions::bytesConcatFunction(vector<Type const*> const& _argumentTypes)
+string YulUtilFunctions::bytesOrStringConcatFunction(
+	vector<Type const*> const& _argumentTypes,
+	FunctionType::Kind _functionTypeKind
+)
 {
-	string functionName = "bytes_concat";
+	solAssert(_functionTypeKind == FunctionType::Kind::BytesConcat || _functionTypeKind == FunctionType::Kind::StringConcat);
+	std::string functionName = (_functionTypeKind == FunctionType::Kind::StringConcat) ? "string_concat" : "bytes_concat";
 	size_t totalParams = 0;
 	vector<Type const*> targetTypes;
+
 	for (Type const* argumentType: _argumentTypes)
 	{
-		solAssert(
+		if (_functionTypeKind == FunctionType::Kind::StringConcat)
-			argumentType->isImplicitlyConvertibleTo(*TypeProvider::bytesMemory()) ||
+			solAssert(argumentType->isImplicitlyConvertibleTo(*TypeProvider::stringMemory()));
-			argumentType->isImplicitlyConvertibleTo(*TypeProvider::fixedBytes(32)),
+		else if (_functionTypeKind == FunctionType::Kind::BytesConcat)
-			""
+			solAssert(
-		);
+				argumentType->isImplicitlyConvertibleTo(*TypeProvider::bytesMemory()) ||
+				argumentType->isImplicitlyConvertibleTo(*TypeProvider::fixedBytes(32))
+			);
+
 		if (argumentType->category() == Type::Category::FixedBytes)
 			targetTypes.emplace_back(argumentType);
 		else if (
@@ -2496,15 +2504,16 @@ string YulUtilFunctions::bytesConcatFunction(vector<Type const*> const& _argumen
 			targetTypes.emplace_back(TypeProvider::fixedBytes(static_cast<unsigned>(literalType->value().size())));
 		else
 		{
-			solAssert(!dynamic_cast<RationalNumberType const*>(argumentType), "");
+			solAssert(!dynamic_cast<RationalNumberType const*>(argumentType));
-			solAssert(argumentType->isImplicitlyConvertibleTo(*TypeProvider::bytesMemory()), "");
+			targetTypes.emplace_back(
-			targetTypes.emplace_back(TypeProvider::bytesMemory());
+				_functionTypeKind == FunctionType::Kind::StringConcat ?
+				TypeProvider::stringMemory() :
+				TypeProvider::bytesMemory()
+			);
 		}
-
 		totalParams += argumentType->sizeOnStack();
 		functionName += "_" + argumentType->identifier();
 	}
-
 	return m_functionCollector.createFunction(functionName, [&]() {
 		Whiskers templ(R"(
 			function <functionName>(<parameters>) -> outPtr {

libsolidity/codegen/YulUtilFunctions.h

@@ -312,9 +312,13 @@ public:
 	/// of the storage array into it.
 	std::string copyArrayFromStorageToMemoryFunction(ArrayType const& _from, ArrayType const& _to);
 
-	/// @returns the name of a function that does concatenation of variadic number of bytes
+	/// @returns the name of a function that does concatenation of variadic number of
-	/// or fixed bytes
+	/// bytes if @a functionTypeKind is FunctionType::Kind::BytesConcat,
-	std::string bytesConcatFunction(std::vector<Type const*> const& _argumentTypes);
+	/// or of strings, if @a functionTypeKind is FunctionType::Kind::StringConcat.
+	std::string bytesOrStringConcatFunction(
+		std::vector<Type const*> const& _argumentTypes,
+		FunctionType::Kind _functionTypeKind
+	);
 
 	/// @returns the name of a function that performs index access for mappings.
 	/// @param _mappingType the type of the mapping

libsolidity/codegen/ir/IRGeneratorForStatements.cpp

@@ -1389,6 +1389,7 @@ void IRGeneratorForStatements::endVisit(FunctionCall const& _functionCall)
 		}
 		break;
 	}
+	case FunctionType::Kind::StringConcat:
 	case FunctionType::Kind::BytesConcat:
 	{
 		TypePointers argumentTypes;
@@ -1399,11 +1400,10 @@ void IRGeneratorForStatements::endVisit(FunctionCall const& _functionCall)
 			argumentVars += IRVariable(*argument).stackSlots();
 		}
 		define(IRVariable(_functionCall)) <<
-			m_utils.bytesConcatFunction(argumentTypes) <<
+			m_utils.bytesOrStringConcatFunction(argumentTypes, functionType->kind()) <<
 			"(" <<
 			joinHumanReadable(argumentVars) <<
 			")\n";
-
 		break;
 	}
 	case FunctionType::Kind::MetaType:

test/libsolidity/semanticTests/strings/concat/string_concat_2_args.sol

@@ -0,0 +1,14 @@
+contract C {
+    function f(string memory a, string memory b) public returns (string memory) {
+        return string.concat(a, b);
+    }
+}
+// ====
+// compileViaYul: also
+// ----
+// f(string,string): 0x40, 0x80, 32, "abcdabcdabcdabcdabcdabcdabcdabcd", 5, "bcdef" -> 0x20, 0x25, 0x6162636461626364616263646162636461626364616263646162636461626364, 44502269928904312298000709931354278973409164155382318144318241583783949107200
+// f(string,string): 0x40, 0xa0, 64, "abcdabcdabcdabcdabcdabcdabcdabcd", "abcdabcdabcdabcdabcdabcdabcdabcd", 5, "bcdef" -> 0x20, 0x45, 0x6162636461626364616263646162636461626364616263646162636461626364, 0x6162636461626364616263646162636461626364616263646162636461626364, 44502269928904312298000709931354278973409164155382318144318241583783949107200
+// f(string,string): 0x40, 0x80, 3, "abc", 3, "def" -> 0x20, 6, "abcdef"
+// f(string,string): 0x40, 0xa0, 34, "abcdabcdabcdabcdabcdabcdabcdabcd", "ab", 30, "cdabcdabcdabcdabcdabcdabcdabcd" -> 0x20, 0x40, 0x6162636461626364616263646162636461626364616263646162636461626364, 0x6162636461626364616263646162636461626364616263646162636461626364
+// f(string,string): 0x40, 0xa0, 34, "abcdabcdabcdabcdabcdabcdabcdabcd", "ab", 34, "cdabcdabcdabcdabcdabcdabcdabcdab", "cd" -> 0x20, 0x44, 0x6162636461626364616263646162636461626364616263646162636461626364, 0x6162636461626364616263646162636461626364616263646162636461626364, 44048183293808120317390542201052832727062033572611867748297851798484192067584
+// f(string,string): 0x40, 0x80, 3, "abc", 30, "dabcdabcdabcdabcdabcdabcdabcda" -> 0x20, 0x21, 0x6162636461626364616263646162636461626364616263646162636461626364, 43874346312576839672212443538448152585028080127215369968075725190498334277632

test/libsolidity/semanticTests/strings/concat/string_concat_different_types.sol

@@ -0,0 +1,37 @@
+contract C{
+    string s = "bcdef";
+
+    function f(string memory a) public returns (string memory) {
+        return string.concat(a, "bcdef");
+    }
+    function g(string calldata a) public returns (string memory) {
+        return string.concat(a, "abcdefghabcdefghabcdefghabcdefghab");
+    }
+    function h(string calldata a) public returns (string memory) {
+        return string.concat(a, s);
+    }
+    function j(string calldata a) public returns (string memory) {
+        string storage ref = s;
+        return string.concat(a, ref, s);
+    }
+    function k(string calldata a, bytes memory b) public returns (string memory) {
+        return string.concat(a, string(b));
+    }
+    function slice(string calldata a) public returns (string memory) {
+        require(bytes(a).length > 2, "");
+        return string.concat(a[:2], a[2:]);
+    }
+    function strParam(bytes calldata a) public returns (string memory) {
+        return string.concat(string(a), "bcdef");
+    }
+}
+// ====
+// compileViaYul: also
+// ----
+// f(string): 0x20, 32, "abcdabcdabcdabcdabcdabcdabcdabcd" -> 0x20, 0x25, 0x6162636461626364616263646162636461626364616263646162636461626364, 44502269928904312298000709931354278973409164155382318144318241583783949107200
+// g(string): 0x20, 32, "abcdabcdabcdabcdabcdabcdabcdabcd" -> 0x20, 0x42, 0x6162636461626364616263646162636461626364616263646162636461626364, 0x6162636465666768616263646566676861626364656667686162636465666768, 44047497324925121336511606693520958599579173549109180625971642598225011015680
+// h(string): 0x20, 32, "abcdabcdabcdabcdabcdabcdabcdabcd" -> 0x20, 0x25, 0x6162636461626364616263646162636461626364616263646162636461626364, 44502269928904312298000709931354278973409164155382318144318241583783949107200
+// j(string): 0x20, 32, "abcdabcdabcdabcdabcdabcdabcdabcd" -> 0x20, 0x2a, 0x6162636461626364616263646162636461626364616263646162636461626364, 44502269928944786876717917111204727192787026596791669343131645116682757734400
+// k(string,bytes): 0x40, 0x80, 32, "abcdabcdabcdabcdabcdabcdabcdabcd", 5, "bcdef" -> 0x20, 0x25, 0x6162636461626364616263646162636461626364616263646162636461626364, 44502269928904312298000709931354278973409164155382318144318241583783949107200
+// slice(string): 0x20, 4, "abcd" -> 0x20, 4, "abcd"
+// strParam(bytes): 0x20, 32, "abcdabcdabcdabcdabcdabcdabcdabcd" -> 0x20, 0x25, 0x6162636461626364616263646162636461626364616263646162636461626364, 44502269928904312298000709931354278973409164155382318144318241583783949107200

test/libsolidity/semanticTests/strings/concat/string_concat_empty_argument_list.sol

@@ -0,0 +1,10 @@
+contract C {
+    function f() public returns (string memory) {
+        return string.concat();
+    }
+}
+// ====
+// compileToEwasm: also
+// compileViaYul: also
+// ----
+// f() -> 0x20, 0

test/libsolidity/semanticTests/strings/concat/string_concat_empty_strings.sol

@@ -0,0 +1,27 @@
+contract C {
+    function f() public returns (string memory) {
+        string memory b = "";
+        return string.concat(
+            string.concat(b),
+            string.concat(b, b),
+            string.concat("", b),
+            string.concat(b, "")
+        );
+    }
+
+    function g() public returns (string memory) {
+        return string.concat("", "abc", hex"", "abc", unicode"");
+    }
+
+    function h() public returns (string memory) {
+        string memory b = "";
+        return string.concat(b, "abc", b, "abc", b);
+    }
+}
+// ====
+// compileToEwasm: also
+// compileViaYul: also
+// ----
+// f() -> 0x20, 0
+// g() -> 0x20, 6, "abcabc"
+// h() -> 0x20, 6, "abcabc"

test/libsolidity/semanticTests/strings/concat/string_concat_nested.sol

@@ -0,0 +1,9 @@
+contract C {
+    function f(string memory a, string memory b, string memory c) public returns (string memory) {
+        return string.concat(string.concat(a, b), c);
+    }
+}
+// ====
+// compileViaYul: also
+// ----
+// f(string,string,string): 0x60, 0x60, 0x60, 2, "ab" -> 0x20, 6, "ababab"

test/libsolidity/syntaxTests/string/concat/string_concat_empty_invalid.sol

@@ -0,0 +1,7 @@
+contract C {
+    function g() public pure returns (string memory) {
+        return string.concat;
+    }
+}
+// ----
+// TypeError 6359: (83-96): Return argument type function () pure returns (string memory) is not implicitly convertible to expected type (type of first return variable) string memory.

test/libsolidity/syntaxTests/string/concat/string_concat_with_different_parameters.sol

@@ -0,0 +1,13 @@
+contract C {
+    function j() external {
+        string memory a = "hello";
+        string memory b = " world";
+
+        string memory d = string.concat(bytes(a), bytes(b));
+        string memory e = string.concat(a, 0);
+    }
+}
+// ----
+// TypeError 9977: (153-161): Invalid type for argument in the string.concat function call. string type is required, but t_bytes_memory_ptr provided.
+// TypeError 9977: (163-171): Invalid type for argument in the string.concat function call. string type is required, but t_bytes_memory_ptr provided.
+// TypeError 9977: (217-218): Invalid type for argument in the string.concat function call. string type is required, but t_rational_0_by_1 provided.

test/libsolidity/syntaxTests/string/concat/string_concat_wrong_type_bytes_and_strings.sol

@@ -0,0 +1,15 @@
+contract C {
+    string s;
+    function f(string calldata c, string calldata c1) public {
+        string memory a;
+        bytes16 b;
+        uint8[] memory num;
+        bytes1[] memory m;
+        string memory d = string.concat(a, b, c, num, s, "abc", m, c1, bytes(c1));
+    }
+}
+// ----
+// TypeError 9977: (232-233): Invalid type for argument in the string.concat function call. string type is required, but t_bytes16 provided.
+// TypeError 9977: (238-241): Invalid type for argument in the string.concat function call. string type is required, but t_array$_t_uint8_$dyn_memory_ptr provided.
+// TypeError 9977: (253-254): Invalid type for argument in the string.concat function call. string type is required, but t_array$_t_bytes1_$dyn_memory_ptr provided.
+// TypeError 9977: (260-269): Invalid type for argument in the string.concat function call. string type is required, but t_bytes_calldata_ptr provided.

test/libsolidity/syntaxTests/string/concat/string_concat_wrong_type_empty_array_literal.sol

@@ -0,0 +1,7 @@
+contract C {
+    function f() public {
+        string.concat([], [], []);
+    }
+}
+// ----
+// TypeError 6378: (61-63): Unable to deduce common type for array elements.

test/libsolidity/syntaxTests/string/concat/string_concat_wrong_type_misc.sol

@@ -0,0 +1,40 @@
+contract C {
+    struct S {
+        uint x;
+    }
+
+    enum E {A, B, C}
+
+    mapping(uint => E) m;
+
+    function f() public {
+        bool b;
+        uint u;
+        uint8 u8;
+        address a;
+        address payable ap;
+        function () external fext;
+        function () internal fint;
+        uint[] memory uDynamic;
+        uint[2] memory uStatic;
+        C c;
+        S memory s;
+        E e;
+
+        string.concat(b, u, u8, a, ap, fext, fint, uDynamic, uStatic, c, s, e, m);
+    }
+}
+// ----
+// TypeError 9977: (426-427): Invalid type for argument in the string.concat function call. string type is required, but t_bool provided.
+// TypeError 9977: (429-430): Invalid type for argument in the string.concat function call. string type is required, but t_uint256 provided.
+// TypeError 9977: (432-434): Invalid type for argument in the string.concat function call. string type is required, but t_uint8 provided.
+// TypeError 9977: (436-437): Invalid type for argument in the string.concat function call. string type is required, but t_address provided.
+// TypeError 9977: (439-441): Invalid type for argument in the string.concat function call. string type is required, but t_address_payable provided.
+// TypeError 9977: (443-447): Invalid type for argument in the string.concat function call. string type is required, but t_function_external_nonpayable$__$returns$__$ provided.
+// TypeError 9977: (449-453): Invalid type for argument in the string.concat function call. string type is required, but t_function_internal_nonpayable$__$returns$__$ provided.
+// TypeError 9977: (455-463): Invalid type for argument in the string.concat function call. string type is required, but t_array$_t_uint256_$dyn_memory_ptr provided.
+// TypeError 9977: (465-472): Invalid type for argument in the string.concat function call. string type is required, but t_array$_t_uint256_$2_memory_ptr provided.
+// TypeError 9977: (474-475): Invalid type for argument in the string.concat function call. string type is required, but t_contract$_C_$86 provided.
+// TypeError 9977: (477-478): Invalid type for argument in the string.concat function call. string type is required, but t_struct$_S_$4_memory_ptr provided.
+// TypeError 9977: (480-481): Invalid type for argument in the string.concat function call. string type is required, but t_enum$_E_$8 provided.
+// TypeError 9977: (483-484): Invalid type for argument in the string.concat function call. string type is required, but t_mapping$_t_uint256_$_t_enum$_E_$8_$ provided.

test/libsolidity/syntaxTests/string/concat/string_concat_wrong_type_misc_literals_and_expressions.sol

@@ -0,0 +1,58 @@
+contract C {
+    struct S {
+        uint x;
+    }
+
+    enum E {A, B, C}
+
+    function f() public {
+        string.concat(
+            false,
+            1,
+            1e10,
+            1e-10,
+            0.1,
+            0x1234567,
+            0x11112222333344445555666677778888999900,     // One byte less than an address
+            0x1111222233334444555566667777888899990000,   // Address
+            0x111122223333444455556666777788889999000011, // One byte more than an address
+            0x00112233445566778899aabbccddeeff00112233445566778899aabbccddeeff,  // exactly 32 bytes
+            -0x0000000000000000000000000000000000000000000000000000000000000001, // exactly 32 bytes
+            bytes(bytes32(0x00112233445566778899aabbccddeeff00112233445566778899aabbccddeeff))[:],
+            f,
+            (),
+            (0, 0),
+            [0],
+            [0][:],
+            [0][0],
+            new C(),
+            S(0),
+            E.A
+        );
+    }
+}
+// ----
+// TypeError 9640: (698-780): Explicit type conversion not allowed from "bytes32" to "bytes memory".
+// TypeError 1227: (698-783): Index range access is only supported for dynamic calldata arrays.
+// TypeError 1227: (865-871): Index range access is only supported for dynamic calldata arrays.
+// TypeError 9977: (134-139): Invalid type for argument in the string.concat function call. string type is required, but t_bool provided.
+// TypeError 9977: (153-154): Invalid type for argument in the string.concat function call. string type is required, but t_rational_1_by_1 provided.
+// TypeError 9977: (168-172): Invalid type for argument in the string.concat function call. string type is required, but t_rational_10000000000_by_1 provided.
+// TypeError 9977: (186-191): Invalid type for argument in the string.concat function call. string type is required, but t_rational_1_by_10000000000 provided.
+// TypeError 9977: (205-208): Invalid type for argument in the string.concat function call. string type is required, but t_rational_1_by_10 provided.
+// TypeError 9977: (222-231): Invalid type for argument in the string.concat function call. string type is required, but t_rational_19088743_by_1 provided.
+// TypeError 9977: (245-285): Invalid type for argument in the string.concat function call. string type is required, but t_rational_380605192295934637532253317235440047844071680_by_1 provided.
+// TypeError 9977: (336-378): Invalid type for argument in the string.concat function call. string type is required, but t_address provided.
+// TypeError 9977: (405-449): Invalid type for argument in the string.concat function call. string type is required, but t_rational_24943341882306372405313753398341798975509081620497_by_1 provided.
+// TypeError 9977: (496-562): Invalid type for argument in the string.concat function call. string type is required, but t_rational_30272441630670900764332283662402067049651745785153368133042924362431065855_by_1 provided.
+// TypeError 9977: (597-664): Invalid type for argument in the string.concat function call. string type is required, but t_rational_minus_1_by_1 provided.
+// TypeError 9977: (698-783): Invalid type for argument in the string.concat function call. string type is required, but t_bytes_memory_ptr_slice provided.
+// TypeError 9977: (797-798): Invalid type for argument in the string.concat function call. string type is required, but t_function_internal_nonpayable$__$returns$__$ provided.
+// TypeError 9977: (812-814): Invalid type for argument in the string.concat function call. string type is required, but t_tuple$__$ provided.
+// TypeError 9977: (828-834): Invalid type for argument in the string.concat function call. string type is required, but t_tuple$_t_rational_0_by_1_$_t_rational_0_by_1_$ provided.
+// TypeError 9977: (848-851): Invalid type for argument in the string.concat function call. string type is required, but t_array$_t_uint8_$1_memory_ptr provided.
+// TypeError 9977: (865-871): Invalid type for argument in the string.concat function call. string type is required, but t_array$_t_uint8_$1_memory_ptr_slice provided.
+// TypeError 9977: (885-891): Invalid type for argument in the string.concat function call. string type is required, but t_uint8 provided.
+// TypeError 9977: (905-912): Invalid type for argument in the string.concat function call. string type is required, but t_contract$_C_$61 provided.
+// TypeError 9977: (926-930): Invalid type for argument in the string.concat function call. string type is required, but t_struct$_S_$4_memory_ptr provided.
+// TypeError 9977: (944-947): Invalid type for argument in the string.concat function call. string type is required, but t_enum$_E_$8 provided.

test/libsolidity/syntaxTests/string/concat/string_concat_wrong_type_zero_literal.sol

@@ -0,0 +1,33 @@
+contract C {
+    function f() public pure {
+        string.concat(
+            0,
+            -0,
+            0.0,
+            -0.0,
+            0e10,
+            -0e10,
+            0e-10,
+            -0e-10,
+            (0),
+            0x00,
+            -0x00,
+            0x0000000000000000000000000000000000000000000000000000000000000000, // exactly 32 bytes
+            -0x0000000000000000000000000000000000000000000000000000000000000000 // exactly 32 bytes
+        );
+    }
+}
+// ----
+// TypeError 9977: (79-80): Invalid type for argument in the string.concat function call. string type is required, but t_rational_0_by_1 provided.
+// TypeError 9977: (94-96): Invalid type for argument in the string.concat function call. string type is required, but t_rational_0_by_1 provided.
+// TypeError 9977: (110-113): Invalid type for argument in the string.concat function call. string type is required, but t_rational_0_by_1 provided.
+// TypeError 9977: (127-131): Invalid type for argument in the string.concat function call. string type is required, but t_rational_0_by_1 provided.
+// TypeError 9977: (145-149): Invalid type for argument in the string.concat function call. string type is required, but t_rational_0_by_1 provided.
+// TypeError 9977: (163-168): Invalid type for argument in the string.concat function call. string type is required, but t_rational_0_by_1 provided.
+// TypeError 9977: (182-187): Invalid type for argument in the string.concat function call. string type is required, but t_rational_0_by_1 provided.
+// TypeError 9977: (201-207): Invalid type for argument in the string.concat function call. string type is required, but t_rational_0_by_1 provided.
+// TypeError 9977: (221-224): Invalid type for argument in the string.concat function call. string type is required, but t_rational_0_by_1 provided.
+// TypeError 9977: (238-242): Invalid type for argument in the string.concat function call. string type is required, but t_rational_0_by_1 provided.
+// TypeError 9977: (256-261): Invalid type for argument in the string.concat function call. string type is required, but t_rational_0_by_1 provided.
+// TypeError 9977: (275-341): Invalid type for argument in the string.concat function call. string type is required, but t_rational_0_by_1 provided.
+// TypeError 9977: (375-442): Invalid type for argument in the string.concat function call. string type is required, but t_rational_0_by_1 provided.