[Bug c++/6730] Crash involving templates when compiling program

[giovannibajo at libero dot it]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=6730



------- Additional Comments From giovannibajo at libero dot it  2003-06-25 16:56 -------
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template <int> 
struct Bar {};

template <typename T>
struct Foo
{
  template <class U> 
  int foo( Bar<sizeof(U::x)>* );
};

template struct Foo<int>;
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During instantiation of Foo, we tsusbt the declarations of the member template 
functions (tsubst_decl, case FUNCTION_DECL), because this is needed to be able 
to unify/call them. 

But when we tsubst the function type and the arguments we fail to realize that 
we are not *instantiating* them, but simply replacing the argument. Thus, the 
build_*() functions do try to perform semantic checks and they crash because 
the types of the (dependent) expressions.

A quick hack is to set processing_template_decl around the two tsubst calls for 
the function type and the arguments. This makes the code compile, but the 
intent of the original poster (using SFINAE to detect the presence of a member 
operator[]) will still not work, since SFINAE is not fully implemented yet.