[LLVMdev] Question about linker error

[Anton Skvorts]

Hello all,

When extending the tutorial to support global variables I'm getting
the following linker error:

glob.o:glob.cpp:(.text+0x12241): undefined reference to `vtable for
GlobalExprAST'
collect2: ld returned 1 exit status

GlobalExprAST class is:

/// GlobalExprAST - Expression class for globals
class GlobalExprAST : public ExprAST {
  std::string Name;
  ExprAST *Init;
public:
  GlobalExprAST(const std::string &name, ExprAST *init)
  : Name(name), Init(init) {}

  virtual Value *Codegen();
};


/// Parser
/// ::= 'global' identifier ('=' expression)?
static ExprAST *ParseGlobalExpr() {
    getNextToken();

    std::string Name = IdentifierStr;
    getNextToken();

    ExprAST *Init = 0;
    if (CurTok == '=') {
      getNextToken();

      Init = ParseExpression();
      if (Init == 0) return 0;
    }
  return new GlobalExprAST(Name, Init);
}

Any help would be much appreaciated!
Anton