Merge pull request #1576 from ethereum/typeIdentifiers

Type identifiers.

libsolidity/ast/AST.h

@@ -59,6 +59,8 @@ public:
 
 	/// @returns an identifier of this AST node that is unique for a single compilation run.
 	size_t id() const { return m_id; }
+	/// Resets the global ID counter. This invalidates all previous IDs.
+	static void resetID();
 
 	virtual void accept(ASTVisitor& _visitor) = 0;
 	virtual void accept(ASTConstVisitor& _visitor) const = 0;
@@ -97,7 +99,7 @@ public:
 	///@}
 
 protected:
-	size_t m_id = 0;
+	size_t const m_id = 0;
 	/// Annotation - is specialised in derived classes, is created upon request (because of polymorphism).
 	mutable ASTAnnotation* m_annotation = nullptr;