Fix ICE when a constant variable declaration forward references a struct

Author: Marenz

Changelog.md

@@ -12,6 +12,7 @@ Compiler Features:
 Bugfixes:
  * Control Flow Graph: Perform proper virtual lookup for modifiers for uninitialized variable and unreachable code analysis.
  * Immutables: Fix wrong error when the constructor of a base contract uses ``return`` and the parent contract contains immutable variables.
+ * TypeChecker: Fix ICE when a constant variable declaration forward references a struct.
 
 
 Solc-Js:

libsolidity/analysis/DeclarationTypeChecker.cpp

@@ -437,16 +437,14 @@ void DeclarationTypeChecker::endVisit(VariableDeclaration const& _variable)
 		type = TypeProvider::withLocation(ref, typeLoc, isPointer);
 	}
 
-	if (
-		_variable.isConstant() &&
-		!dynamic_cast<UserDefinedValueType const*>(type) &&
-		type->containsNestedMapping()
-	)
-		m_errorReporter.fatalDeclarationError(
-			3530_error,
-			_variable.location(),
-			"The type contains a (nested) mapping and therefore cannot be a constant."
-		);
+	if (_variable.isConstant() && !type->isValueType())
+	{
+		bool allowed = false;
+		if (auto arrayType = dynamic_cast<ArrayType const*>(type))
+			allowed = arrayType->isByteArray();
+		if (!allowed)
+			m_errorReporter.fatalTypeError(9259_error, _variable.location(), "Only constants of value type and byte array type are implemented.");
+	}
 
 	_variable.annotation().type = type;
 }

libsolidity/analysis/TypeChecker.cpp

@@ -530,15 +530,6 @@ bool TypeChecker::visit(VariableDeclaration const& _variable)
 	}
 	if (_variable.isConstant())
 	{
-		if (!varType->isValueType())
-		{
-			bool allowed = false;
-			if (auto arrayType = dynamic_cast<ArrayType const*>(varType))
-				allowed = arrayType->isByteArray();
-			if (!allowed)
-				m_errorReporter.fatalTypeError(9259_error, _variable.location(), "Constants of non-value type not yet implemented.");
-		}
-
 		if (!_variable.value())
 			m_errorReporter.typeError(4266_error, _variable.location(), "Uninitialized \"constant\" variable.");
 		else if (!*_variable.value()->annotation().isPure)

libsolidity/ast/Types.h

@@ -1110,11 +1110,7 @@ class UserDefinedValueType: public Type
 	u256 storageSize() const override { return underlyingType().storageSize(); }
 	unsigned storageBytes() const override { return underlyingType().storageBytes(); }
 
-	bool isValueType() const override
-	{
-		solAssert(underlyingType().isValueType(), "");
-		return true;
-	}
+	bool isValueType() const override { return true; }
 	bool nameable() const override
 	{
 		solAssert(underlyingType().nameable(), "");

test/libsolidity/syntaxTests/constantEvaluator/type_reference.sol

@@ -1,3 +1,4 @@
 int[L] constant L = 6;
 // ----
 // TypeError 5462: (4-5): Invalid array length, expected integer literal or constant expression.
+// TypeError 9259: (0-21): Only constants of value type and byte arrays are implemented.

test/libsolidity/syntaxTests/constantEvaluator/type_reference_in_contract.sol

@@ -3,3 +3,4 @@ contract C {
 }
 // ----
 // TypeError 5462: (21-22): Invalid array length, expected integer literal or constant expression.
+// TypeError 9259: (17-38): Only constants of value type and byte arrays are implemented.

test/libsolidity/syntaxTests/constants/mapping_constant.sol

@@ -1,3 +1,3 @@
 mapping(uint => uint) constant b = b;
 // ----
-// DeclarationError 3530: (0-36): The type contains a (nested) mapping and therefore cannot be a constant.
+// TypeError 9259: (0-36): Only constants of value type and byte arrays are implemented.

test/libsolidity/syntaxTests/constants/struct_constant.sol

@@ -1,4 +1,4 @@
 struct S { uint x; }
 S constant s;
 // ----
-// TypeError 9259: (21-33): Constants of non-value type not yet implemented.
+// TypeError 9259: (21-33): Only constants of value type and byte arrays are implemented.

test/libsolidity/syntaxTests/iceRegressionTests/const_struct_with_mapping.sol

@@ -5,4 +5,4 @@ contract C {
     S public constant e = 0x1212121212121212121212121212121212121212;
 }
 // ----
-// DeclarationError 3530: (71-135): The type contains a (nested) mapping and therefore cannot be a constant.
+// TypeError 9259: (71-135): Only constants of value type and byte arrays are implemented.

test/libsolidity/syntaxTests/nameAndTypeResolution/105_constant_input_parameter.sol

@@ -3,3 +3,4 @@ contract test {
 }
 // ----
 // DeclarationError 1788: (31-55): The "constant" keyword can only be used for state variables or variables at file level.
+// TypeError 9259: (31-55): Only constants of value type and byte arrays are implemented.