[cfe-commits] r72844 - in /cfe/trunk: lib/Sema/SemaTemplateDeduction.cpp test/SemaTemplate/temp_class_spec.cpp

[Douglas Gregor]

On Jun 3, 2009, at 9:11 PM, Anders Carlsson wrote:

> Author: andersca
> Date: Wed Jun  3 23:11:30 2009
> New Revision: 72844
>
> URL: http://llvm.org/viewvc/llvm-project?rev=72844&view=rev
> Log:
> Template argument deduction for incomplete and constant array types.  
> Doug, please review.

Cool.

> Modified:
>    cfe/trunk/lib/Sema/SemaTemplateDeduction.cpp
>    cfe/trunk/test/SemaTemplate/temp_class_spec.cpp
>
> Modified: cfe/trunk/lib/Sema/SemaTemplateDeduction.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaTemplateDeduction.cpp?rev=72844&r1=72843&r2=72844&view=diff
>
> = 
> = 
> = 
> = 
> = 
> = 
> = 
> = 
> ======================================================================
> --- cfe/trunk/lib/Sema/SemaTemplateDeduction.cpp (original)
> +++ cfe/trunk/lib/Sema/SemaTemplateDeduction.cpp Wed Jun  3 23:11:30  
> 2009
> @@ -100,6 +100,35 @@
>                                      Deduced);
>     }
>
> +    case Type::IncompleteArray: {
> +      const IncompleteArrayType *IncompleteArrayArg =
> +        Context.getAsIncompleteArrayType(Arg);
> +      if (!IncompleteArrayArg)
> +        return false;
> +
> +      return DeduceTemplateArguments(Context,
> +                     Context.getAsIncompleteArrayType(Param)- 
> >getElementType(),
> +                                     IncompleteArrayArg- 
> >getElementType(),
> +                                     Deduced);
> +    }

Looks good.

> +    case Type::ConstantArray: {
> +      const ConstantArrayType *ConstantArrayArg =
> +        Context.getAsConstantArrayType(Arg);
> +      if (!ConstantArrayArg)
> +        return false;
> +
> +      const ConstantArrayType *ConstantArrayParm =
> +        Context.getAsConstantArrayType(Param);
> +      if (ConstantArrayArg->getSize() != ConstantArrayParm- 
> >getSize())
> +        return false;

We can deduce the value of a non-type template parameter from an array  
bound, so we'll need to call into a new version of  
DeduceTemplateArguments here that can handle expressions. Example code:

   template<typename T> struct is_array { static const bool value =  
false; };
   template<typename T, unsigned N> struct is_array<T[N]> { static  
const bool value = true; };

is_array<int[12]>::value will be true, and we'll deduce T=int and N=12.

At the very least, please add a FIXME.

> +      return DeduceTemplateArguments(Context,
> +                                     ConstantArrayParm- 
> >getElementType(),
> +                                     ConstantArrayArg- 
> >getElementType(),
> +                                     Deduced);
> +    }
> +
>     default:
>       break;
>   }

Looks good!

	- Doug