[cfe-dev] Problems in clang/AST/ASTConsumer.h

[Simone Pellegrini]

Hi,
I'm extending the ASTConsumer class to make some custom analysis on the 
Syntax tree created by clang in the following way:

class MyASTConsumer: public ASTConsumer {
    ...
}

when I try to compile my program using the g++ compiler (I've used both 
the gcc 3.4.6 and gcc 4.3.2). I get the following error:

build/main.o(.gnu.linkonce.r._ZTI13MyASTConsumer+0x10): undefined 
reference to `typeinfo for clang::ASTConsumer'
collect2: ld returned 1 exit status

Apparently the error is caused by the empty virtual definition of 
ASTConsumer methods:
 virtual ~ASTConsumer();
 virtual void InitializeTU(TranslationUnit& TU) ;

changing this declaration (in the ASTConsumer.h file) into:
 virtual ~ASTConsumer() {}
 virtual void InitializeTU(TranslationUnit& TU) {}
or:
 virtual ~ASTConsumer() = 0;
 virtual void InitializeTU(TranslationUnit& TU) = 0;

fixes the problem for me! Of course in the second problem I have to 
provide an implementation for both the methods in my class.

I hope it helps,
greetings Simone