From f70ffa4f4b336215ce15ce4c4cc6c5b935cc5d7a Mon Sep 17 00:00:00 2001
From: Christian Parpart <christian@parpart.family>
Date: Wed, 22 Jul 2020 11:53:35 +0200
Subject: [PATCH] WIP: error type

---
 libsolidity/ast/AST.h            | 41 ++++++++++++++++++++++++++++++++
 libsolidity/ast/ASTAnnotations.h |  5 ++++
 libsolidity/ast/ASTForward.h     |  1 +
 libsolidity/ast/Types.h          | 11 ++++++++-
 4 files changed, 57 insertions(+), 1 deletion(-)

diff --git a/libsolidity/ast/AST.h b/libsolidity/ast/AST.h
index 34fefeb0a..a93161f47 100644
--- a/libsolidity/ast/AST.h
+++ b/libsolidity/ast/AST.h
@@ -594,6 +594,47 @@ private:
 	ASTPointer<TypeName> m_typeName;
 };
 
+template <typename AnnotationT>
+class CompositeType: public Declaration
+{
+public:
+	CompositeType(
+		int64_t _id,
+		SourceLocation const& _location,
+		ASTPointer<ASTString> const& _name,
+		std::vector<ASTPointer<VariableDeclaration>> _members
+	):
+		Declaration(_id, _location, _name), m_members(std::move(_members)) {}
+
+	void accept(ASTVisitor& _visitor) override;
+	void accept(ASTConstVisitor& _visitor) const override;
+
+	std::vector<ASTPointer<VariableDeclaration>> const& members() const { return m_members; }
+
+	TypePointer type() const override
+	{
+		return TypeProvider::typeType(TypeProvider::errorType(*this, DataLocation::Storage));
+	}
+
+	bool isVisibleInDerivedContracts() const override { return true; }
+	bool isVisibleViaContractTypeAccess() const override { return true; }
+
+	AnnotationT& annotation() const override;
+
+private:
+	std::vector<ASTPointer<VariableDeclaration>> m_members;
+};
+using ErrorDefinition = CompositeType<ErrorDeclarationAnnotation>;
+TypePointer ErrorDefinition::type() const
+{
+}
+
+ErrorDeclarationAnnotation& ErrorDefinition::annotation() const
+{
+	return initAnnotation<ErrorDeclarationAnnotation>();
+}
+
+
 class StructDefinition: public Declaration
 {
 public:
diff --git a/libsolidity/ast/ASTAnnotations.h b/libsolidity/ast/ASTAnnotations.h
index 507559ca6..1e65c00b0 100644
--- a/libsolidity/ast/ASTAnnotations.h
+++ b/libsolidity/ast/ASTAnnotations.h
@@ -138,6 +138,11 @@ struct StructDeclarationAnnotation: TypeDeclarationAnnotation
 	std::optional<bool> recursive;
 };
 
+struct ErrorDeclarationAnnotation: TypeDeclarationAnnotation
+{
+	// currently no annotations
+};
+
 struct ContractDefinitionAnnotation: TypeDeclarationAnnotation, StructurallyDocumentedAnnotation
 {
 	/// List of functions and modifiers without a body. Can also contain functions from base classes.
diff --git a/libsolidity/ast/ASTForward.h b/libsolidity/ast/ASTForward.h
index 38da35218..28c5915c9 100644
--- a/libsolidity/ast/ASTForward.h
+++ b/libsolidity/ast/ASTForward.h
@@ -47,6 +47,7 @@ class ContractDefinition;
 class InheritanceSpecifier;
 class UsingForDirective;
 class StructDefinition;
+class ErrorDefinition;
 class EnumDefinition;
 class EnumValue;
 class ParameterList;
diff --git a/libsolidity/ast/Types.h b/libsolidity/ast/Types.h
index 155fa7f14..498ca5ae2 100644
--- a/libsolidity/ast/Types.h
+++ b/libsolidity/ast/Types.h
@@ -171,11 +171,12 @@ public:
 	enum class Category
 	{
 		Address, Integer, RationalNumber, StringLiteral, Bool, FixedPoint, Array, ArraySlice,
-		FixedBytes, Contract, Struct, Function, Enum, Tuple,
+		FixedBytes, Contract, Struct, Error, Function, Enum, Tuple,
 		Mapping, TypeType, Modifier, Magic, Module,
 		InaccessibleDynamic
 	};
 
+
 	/// @returns a pointer to _a or _b if the other is implicitly convertible to it or nullptr otherwise
 	static TypePointer commonType(Type const* _a, Type const* _b);
 
@@ -1002,6 +1003,14 @@ private:
 	mutable std::optional<TypeResult> m_interfaceType_library;
 };
 
+class ErrorType: public StructType
+{
+public:
+	explicit ErrorType(ErrorDefinition const& _def):
+		StructType{_def, DataLocation::Memory}
+	{}
+};
+
 /**
  * The type of an enum instance, there is one distinct type per enum definition.
  */