[cfe-commits] r67226 - /cfe/trunk/lib/Sema/SemaTemplateInstantiate.cpp

[Douglas Gregor]

On Mar 18, 2009, at 1:12 PM, Gabor Greif wrote:

> Author: ggreif
> Date: Wed Mar 18 15:12:58 2009
> New Revision: 67226
>
> URL: http://llvm.org/viewvc/llvm-project?rev=67226&view=rev
> Log:
> incorporate review comment (about the optimization when we have a  
> non-typedependent expression)
>
> Modified:
>    cfe/trunk/lib/Sema/SemaTemplateInstantiate.cpp
>
> Modified: cfe/trunk/lib/Sema/SemaTemplateInstantiate.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaTemplateInstantiate.cpp?rev=67226&r1=67225&r2=67226&view=diff
>
> = 
> = 
> = 
> = 
> = 
> = 
> = 
> = 
> ======================================================================
> --- cfe/trunk/lib/Sema/SemaTemplateInstantiate.cpp (original)
> +++ cfe/trunk/lib/Sema/SemaTemplateInstantiate.cpp Wed Mar 18  
> 15:12:58 2009
> @@ -839,8 +839,24 @@
>   if (False.isInvalid())
>     return SemaRef.ExprError();
>
> -  return SemaRef.ActOnConditionalOp(E->getCond()->getLocEnd(),
> -                                    E->getFalseExpr()->getLocStart(),
> +  if (!E->isTypeDependent()) {
> +    // Since our original expression was not type-dependent, we do  
> not
> +    // perform lookup again at instantiation time (C++ [temp.dep]p1).
> +    // Instead, we just build the new conditional operator call  
> expression.
> +    Cond.release();
> +    True.release();
> +    False.release();
> +    // FIXME: Don't reuse the parts here. We need to instantiate  
> them.
> +    return SemaRef.Owned(new (SemaRef.Context) ConditionalOperator(
> +                                                              E- 
> >getCond(),
> +                                                              E- 
> >getTrueExpr(),
> +                                                              E- 
> >getFalseExpr(),
> +                                                              E- 
> >getType()));
> +  }

Getting closer. This will do the wrong thing when E->getCond() is type- 
dependent but E->getTrueExpr() and E->getFalseExpr() are not type- 
dependent. In this case, E is not type-dependent, even though we still  
need to check that the instantiated Cond is convertible to bool.  
Example:

	sizeof(T() + U()? sizeof(T) : sizeof(U))

Here, the ? : expression is not type-dependent (it's type is known to  
be size_t), but after instantiation we still need to perform the  
contextual conversion of the instantiated T() + U() to bool.

Also, when creating the ConditionalOperation, you'll need to pass it  
the instantiated values Cond.release(), True.release(), and  
False.release() rather than the uninstantiated E->getCond(), E- 
 >getTrueExpr(), and E->getFalseExpr().

	- Doug