Merge pull request #11847 from ethereum/enum-min-max-11469

Add type().min/max for enums

Changelog.md

@@ -2,6 +2,7 @@
 
 Language Features:
  * Inheritance: A function that overrides only a single interface function does not require the ``override`` specifier.
+ * Type System: Support ``type().min`` and ``type().max`` for enums.
 
 
 Compiler Features:

docs/types/value-types.rst

@@ -587,11 +587,14 @@ Enums cannot have more than 256 members.
 The data representation is the same as for enums in C: The options are represented by
 subsequent unsigned integer values starting from ``0``.
 
+Using ``type(NameOfEnum).min`` and ``type(NameOfEnum).max`` you can get the
+smallest and respectively largest value of the given enum.
+
 
 .. code-block:: solidity
 
     // SPDX-License-Identifier: GPL-3.0
-    pragma solidity >=0.4.16 <0.9.0;
+    pragma solidity ^0.8.8;
 
     contract test {
         enum ActionChoices { GoLeft, GoRight, GoStraight, SitStill }
@@ -612,6 +615,14 @@ subsequent unsigned integer values starting from ``0``.
         function getDefaultChoice() public pure returns (uint) {
             return uint(defaultChoice);
         }
+
+        function getLargestValue() public pure returns (ActionChoices) {
+            return type(ActionChoices).max;
+        }
+
+        function getSmallestValue() public pure returns (ActionChoices) {
+            return type(ActionChoices).min;
+        }
     }
 
 .. note::

libsolidity/analysis/TypeChecker.cpp

@@ -246,7 +246,10 @@ TypePointers TypeChecker::typeCheckMetaTypeFunctionAndRetrieveReturnType(Functio
 		Type::Category typeCategory = typeTypePtr->actualType()->category();
 		if (auto const* contractType = dynamic_cast<ContractType const*>(typeTypePtr->actualType()))
 			wrongType = contractType->isSuper();
-		else if (typeCategory != Type::Category::Integer)
+		else if (
+			typeCategory != Type::Category::Integer &&
+			typeCategory != Type::Category::Enum
+		)
 			wrongType = true;
 	}
 	else
@@ -257,7 +260,7 @@ TypePointers TypeChecker::typeCheckMetaTypeFunctionAndRetrieveReturnType(Functio
 			4259_error,
 			arguments.front()->location(),
 			"Invalid type for argument in the function call. "
-			"A contract type or an integer type is required, but " +
+			"An enum type, contract type or an integer type is required, but " +
 			type(*arguments.front())->toString(true) + " provided."
 		);
 

libsolidity/ast/TypeProvider.cpp

@@ -566,9 +566,10 @@ MagicType const* TypeProvider::meta(Type const* _type)
 	solAssert(
 		_type && (
 			_type->category() == Type::Category::Contract ||
-			_type->category() == Type::Category::Integer
+			_type->category() == Type::Category::Integer ||
+			_type->category() == Type::Category::Enum
 		),
-		"Only contracts or integer types supported for now."
+		"Only enum, contracts or integer types supported for now."
 	);
 	return createAndGet<MagicType>(_type);
 }

libsolidity/ast/Types.cpp

@@ -3961,9 +3961,10 @@ MemberList::MemberMap MagicType::nativeMembers(ASTNode const*) const
 		solAssert(
 			m_typeArgument && (
 					m_typeArgument->category() == Type::Category::Contract ||
-					m_typeArgument->category() == Type::Category::Integer
+					m_typeArgument->category() == Type::Category::Integer ||
+					m_typeArgument->category() == Type::Category::Enum
 			),
-			"Only contracts or integer types supported for now"
+			"Only enums, contracts or integer types supported for now"
 		);
 
 		if (m_typeArgument->category() == Type::Category::Contract)
@@ -3989,6 +3990,14 @@ MemberList::MemberMap MagicType::nativeMembers(ASTNode const*) const
 				{"max", integerTypePointer},
 			});
 		}
+		else if (m_typeArgument->category() == Type::Category::Enum)
+		{
+			EnumType const* enumTypePointer = dynamic_cast<EnumType const*>(m_typeArgument);
+			return MemberList::MemberMap({
+				{"min", enumTypePointer},
+				{"max", enumTypePointer},
+			});
+		}
 	}
 	}
 	solAssert(false, "Unknown kind of magic.");

libsolidity/ast/Types.h

@@ -1071,6 +1071,12 @@ public:
 	/// @returns the value that the string has in the Enum
 	unsigned int memberValue(ASTString const& _member) const;
 	size_t numberOfMembers() const;
+	unsigned int minValue() const { return 0; }
+	unsigned int maxValue() const
+	{
+		solAssert(numberOfMembers() <= 256, "");
+		return static_cast<unsigned int>(numberOfMembers()) - 1;
+	}
 
 private:
 	EnumDefinition const& m_enum;

libsolidity/codegen/ExpressionCompiler.cpp

@@ -1784,12 +1784,13 @@ bool ExpressionCompiler::visit(MemberAccess const& _memberAccess)
 		else if (member == "min" || member == "max")
 		{
 			MagicType const* arg = dynamic_cast<MagicType const*>(_memberAccess.expression().annotation().type);
-			IntegerType const* integerType = dynamic_cast<IntegerType const*>(arg->typeArgument());
-
-			if (member == "min")
-				m_context << integerType->min();
+			if (IntegerType const* integerType = dynamic_cast<IntegerType const*>(arg->typeArgument()))
+				m_context << (member == "min" ? integerType->min() : integerType->max());
+			else if (EnumType const* enumType = dynamic_cast<EnumType const*>(arg->typeArgument()))
+				m_context << (member == "min" ? enumType->minValue() : enumType->maxValue());
 			else
-				m_context << integerType->max();
+				solAssert(false, "min/max not available for the given type.");
+
 		}
 		else if ((set<string>{"encode", "encodePacked", "encodeWithSelector", "encodeWithSignature", "decode"}).count(member))
 		{

libsolidity/codegen/ir/IRGeneratorForStatements.cpp

@@ -1785,12 +1785,26 @@ void IRGeneratorForStatements::endVisit(MemberAccess const& _memberAccess)
 		else if (member == "min" || member == "max")
 		{
 			MagicType const* arg = dynamic_cast<MagicType const*>(_memberAccess.expression().annotation().type);
-			IntegerType const* integerType = dynamic_cast<IntegerType const*>(arg->typeArgument());
 
-			if (member == "min")
-				define(_memberAccess) << formatNumber(integerType->min()) << "\n";
+			string requestedValue;
+			if (IntegerType const* integerType = dynamic_cast<IntegerType const*>(arg->typeArgument()))
+			{
+				if (member == "min")
+					requestedValue = formatNumber(integerType->min());
+				else
+					requestedValue = formatNumber(integerType->max());
+			}
+			else if (EnumType const* enumType = dynamic_cast<EnumType const*>(arg->typeArgument()))
+			{
+				if (member == "min")
+					requestedValue = to_string(enumType->minValue());
+				else
+					requestedValue = to_string(enumType->maxValue());
+			}
 			else
-				define(_memberAccess) << formatNumber(integerType->max()) << "\n";
+				solAssert(false, "min/max requested on unexpected type.");
+
+			define(_memberAccess) << requestedValue << "\n";
 		}
 		else if (set<string>{"encode", "encodePacked", "encodeWithSelector", "encodeWithSignature", "decode"}.count(member))
 		{

libsolidity/formal/SMTEncoder.cpp

@@ -1284,8 +1284,10 @@ bool SMTEncoder::visit(MemberAccess const& _memberAccess)
 			auto const& memberName = _memberAccess.memberName();
 			if (memberName == "min" || memberName == "max")
 			{
-				IntegerType const& integerType = dynamic_cast<IntegerType const&>(*magicType->typeArgument());
-				defineExpr(_memberAccess, memberName == "min" ? integerType.minValue() : integerType.maxValue());
+				if (IntegerType const* integerType = dynamic_cast<IntegerType const*>(magicType->typeArgument()))
+					defineExpr(_memberAccess, memberName == "min" ? integerType->minValue() : integerType->maxValue());
+				else if (EnumType const* enumType = dynamic_cast<EnumType const*>(magicType->typeArgument()))
+					defineExpr(_memberAccess, memberName == "min" ? enumType->minValue() : enumType->maxValue());
 			}
 			else if (memberName == "interfaceId")
 			{

test/libsolidity/semanticTests/enums/minmax.sol

@@ -0,0 +1,12 @@
+contract test {
+	enum MinMax { A, B, C, D }
+
+	function min() public returns(uint) { return uint(type(MinMax).min); }
+	function max() public returns(uint) { return uint(type(MinMax).max); }
+}
+
+// ====
+// compileViaYul: also
+// ----
+// min() -> 0
+// max() -> 3

test/libsolidity/syntaxTests/array/concat/bytes_concat_on_type_info.sol

@@ -5,4 +5,4 @@ contract C {
     }
 }
 // ----
-// TypeError 4259: (93-98): Invalid type for argument in the function call. A contract type or an integer type is required, but type(bytes) provided.
+// TypeError 4259: (93-98): Invalid type for argument in the function call. An enum type, contract type or an integer type is required, but type(bytes) provided.

test/libsolidity/syntaxTests/metaTypes/codeAccess_super.sol

@@ -10,4 +10,4 @@ contract SuperTest is Other {
 	}
 }
 // ----
-// TypeError 4259: (177-182): Invalid type for argument in the function call. A contract type or an integer type is required, but type(contract super SuperTest) provided.
+// TypeError 4259: (177-182): Invalid type for argument in the function call. An enum type, contract type or an integer type is required, but type(contract super SuperTest) provided.

test/libsolidity/syntaxTests/metaTypes/interfaceid_super.sol

@@ -14,4 +14,4 @@ abstract contract Test is ERC165 {
     }
 }
 // ----
-// TypeError 4259: (592-597): Invalid type for argument in the function call. A contract type or an integer type is required, but type(contract super Test) provided.
+// TypeError 4259: (592-597): Invalid type for argument in the function call. An enum type, contract type or an integer type is required, but type(contract super Test) provided.

test/libsolidity/syntaxTests/metaTypes/super_name.sol

@@ -50,4 +50,4 @@ contract D is B, C {
     }
 }
 // ----
-// TypeError 4259: (426-431): Invalid type for argument in the function call. A contract type or an integer type is required, but type(contract super B) provided.
+// TypeError 4259: (426-431): Invalid type for argument in the function call. An enum type, contract type or an integer type is required, but type(contract super B) provided.

test/libsolidity/syntaxTests/metaTypes/typeRecursive.sol

@@ -4,4 +4,4 @@ contract Test {
     }
 }
 // ----
-// TypeError 4259: (65-75): Invalid type for argument in the function call. A contract type or an integer type is required, but type(contract Test) provided.
+// TypeError 4259: (65-75): Invalid type for argument in the function call. An enum type, contract type or an integer type is required, but type(contract Test) provided.

test/libsolidity/syntaxTests/metaTypes/unsupportedArgForType.sol

@@ -6,4 +6,4 @@ contract Test {
     }
 }
 // ----
-// TypeError 4259: (154-155): Invalid type for argument in the function call. A contract type or an integer type is required, but type(struct Test.S) provided.
+// TypeError 4259: (154-155): Invalid type for argument in the function call. An enum type, contract type or an integer type is required, but type(struct Test.S) provided.

test/libsolidity/syntaxTests/tryCatch/no_special.sol

@@ -14,4 +14,4 @@ contract C {
 // ----
 // TypeError 5347: (72-76): Try can only be used with external function calls and contract creation calls.
 // TypeError 2536: (119-128): Try can only be used with external function calls and contract creation calls.
-// TypeError 4259: (176-183): Invalid type for argument in the function call. A contract type or an integer type is required, but type(address) provided.
+// TypeError 4259: (176-183): Invalid type for argument in the function call. An enum type, contract type or an integer type is required, but type(address) provided.